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1.  Persistence of HIV-1 Transmitted Drug Resistance Mutations 
The Journal of Infectious Diseases  2013;208(9):1459-1463.
There are few data on the persistence of individual human immunodeficiency virus type 1 (HIV-1) transmitted drug resistance (TDR) mutations in the absence of selective drug pressure. We studied 313 patients in whom TDR mutations were detected at their first resistance test and who had a subsequent test performed while ART-naive. The rate at which mutations became undetectable was estimated using exponential regression accounting for interval censoring. Most thymidine analogue mutations (TAMs) and T215 revertants (but not T215F/Y) were found to be highly stable, with NNRTI and PI mutations being relatively less persistent. Our estimates are important for informing HIV transmission models.
doi:10.1093/infdis/jit345
PMCID: PMC3789571  PMID: 23904291
persistence; transmitted; HIV-1; resistance; mutations
2.  Low frequency of genotypic resistance in HIV-1-infected patients failing an atazanavir-containing regimen: a clinical cohort study 
Dolling, David I. | Dunn, David T. | Sutherland, Katherine A. | Pillay, Deenan | Mbisa, Jean L. | Parry, Chris M. | Post, Frank A. | Sabin, Caroline A. | Cane, Patricia A. | Aitken, Celia | Asboe, David | Webster, Daniel | Cane, Patricia | Castro, Hannah | Dunn, David | Dolling, David | Chadwick, David | Churchill, Duncan | Clark, Duncan | Collins, Simon | Delpech, Valerie | Geretti, Anna Maria | Goldberg, David | Hale, Antony | Hué, Stéphane | Kaye, Steve | Kellam, Paul | Lazarus, Linda | Leigh-Brown, Andrew | Mackie, Nicola | Orkin, Chloe | Rice, Philip | Pillay, Deenan | Phillips, Andrew | Sabin, Caroline | Smit, Erasmus | Templeton, Kate | Tilston, Peter | Tong, William | Williams, Ian | Zhang, Hongyi | Zuckerman, Mark | Greatorex, Jane | Wildfire, Adrian | O'Shea, Siobhan | Mullen, Jane | Mbisa, Tamyo | Cox, Alison | Tandy, Richard | Hale, Tony | Fawcett, Tracy | Hopkins, Mark | Ashton, Lynn | Booth, Claire | Garcia-Diaz, Ana | Shepherd, Jill | Schmid, Matthias L. | Payne, Brendan | Hay, Phillip | Rice, Phillip | Paynter, Mary | Bibby, David | Kirk, Stuart | MacLean, Alasdair | Gunson, Rory | Coughlin, Kate | Fearnhill, Esther | Fradette, Lorraine | Porter, Kholoud | Ainsworth, Jonathan | Anderson, Jane | Babiker, Abdel | Fisher, Martin | Gazzard, Brian | Gilson, Richard | Gompels, Mark | Hill, Teresa | Johnson, Margaret | Kegg, Stephen | Leen, Clifford | Nelson, Mark | Palfreeman, Adrian | Post, Frank | Sachikonye, Memory | Schwenk, Achim | Walsh, John | Huntington, Susie | Jose, Sophie | Thornton, Alicia | Glabay, Adam | Orkin, C. | Garrett, N. | Lynch, J. | Hand, J. | de Souza, C. | Fisher, M. | Perry, N. | Tilbury, S. | Gazzard, B. | Nelson, M. | Waxman, M. | Asboe, D. | Mandalia, S. | Delpech, V. | Anderson, J. | Munshi, S. | Korat, H. | Welch, J. | Poulton, M. | MacDonald, C. | Gleisner, Z. | Campbell, L. | Gilson, R. | Brima, N. | Williams, I. | Schwenk, A. | Ainsworth, J. | Wood, C. | Miller, S. | Johnson, M. | Youle, M. | Lampe, F. | Smith, C. | Grabowska, H. | Chaloner, C. | Puradiredja, D. | Walsh, J. | Weber, J. | Ramzan, F. | Mackie, N. | Winston, A. | Leen, C. | Wilson, A. | Allan, S. | Palfreeman, A. | Moore, A. | Wakeman, K.
Journal of Antimicrobial Chemotherapy  2013;68(10):2339-2343.
Objectives
To determine protease mutations that develop at viral failure for protease inhibitor (PI)-naive patients on a regimen containing the PI atazanavir.
Methods
Resistance tests on patients failing atazanavir, conducted as part of routine clinical care in a multicentre observational study, were randomly matched by subtype to resistance tests from PI-naive controls to account for natural polymorphisms. Mutations from the consensus B sequence across the protease region were analysed for association and defined using the IAS-USA 2011 classification list.
Results
Four hundred and five of 2528 (16%) patients failed therapy containing atazanavir as a first PI over a median (IQR) follow-up of 1.76 (0.84–3.15) years and 322 resistance tests were available for analysis. Recognized major atazanavir mutations were found in six atazanavir-experienced patients (P < 0.001), including I50L and N88S. The minor mutations most strongly associated with atazanavir experience were M36I, M46I, F53L, A71V, V82T and I85V (P < 0.05). Multiple novel mutations, I15S, L19T, K43T, L63P/V, K70Q, V77I and L89I/T/V, were also associated with atazanavir experience.
Conclusions
Viral failure on atazanavir-containing regimens was not common and major resistance mutations were rare, suggesting that adherence may be a major contributor to viral failure. Novel mutations were described that have not been previously documented.
doi:10.1093/jac/dkt199
PMCID: PMC3772741  PMID: 23711895
HIV; drug resistance mutations; naive patients; protease inhibitors; virological failure
3.  Does pregnancy increase the risk of ART-induced hepatotoxicity among HIV-positive women? 
Journal of the International AIDS Society  2014;17(4Suppl 3):19486.
Introduction
High rates of hepatotoxicity have been observed among HIV-positive pregnant women using antiretroviral therapy (ART). However, the extent to which pregnancy affects the risk of ART-induced hepatotoxicity is unclear since studies in this area have generated conflicting results.
Material and Methods
Combined data from the UK Collaborative HIV Cohort (UK CHIC) study and the UK and Ireland National Study of HIV in Pregnancy and Childhood (NSHPC) were used. Alanine aminotransferase (ALT) data were assessed according to the Division of AIDS toxicity guidelines to identify factors associated with liver enzyme elevation (LEE) (grade 1–4). Women starting ART in 2000–11 aged 16–49 years were included irrespective of pregnancy status at ART start. Cox proportional hazards were used to assess the associations between fixed (ethnicity, exposure group, HBV/HCV co-infection, prior ART use, and age, year, pregnancy status, viral load and CD4 count at ART start) and time-dependent covariates (pregnancy status, age, year, CD4 count, viral load, duration on ART) and the risk of LEE.
Results
Of the 3426 women included, one-quarter (25.0%, n=857) were pregnant during follow-up and 14.4% (n=492) started ART during pregnancy. The rate of LEE was 15/100 person-years (PY) during pregnancy and 6.1/100 PY outside pregnancy. The risk of LEE was increased during pregnancy (adjusted hazard ratio (aHR) 1.61 [1.26–2.06], p<0.001), including in secondary analysis excluding 493 women pregnant when starting ART. Other factors independently associated with LEE were lower CD4 count (<250 cells/mm3 vs. 251–350 cells/mm3 aHR 1.25 [1.02–1.54], p=0.03), HBV/HCV co-infection (aHR 1.94 [1.58–2.39], p<0.001), HIV acquired via injecting drug use (aHR 1.61 [1.15–2.24], p=0.01 vs. heterosexually) and calendar year (aHR 1.05 [1.02–1.08], p<0.001 per one year increase). Three ART drugs were associated with increased risk of LEE (efavirenz aHR 1.27 [1.06–1.50], p-value 0.008; maraviroc 4.19 [1.34–13.1], p=0.01; and nevirapine 1.59 [1.30–1.95], p-value <0.001). Use of zidovudine was associated with decreased risk of LEE (aHR 0.74 [0.63–0.87], p<0.001) as was increasing time on an NNRTI-based regimen (aHR 0.91 [0.86–0.96], p<0.001 per additional year).
Conclusions
Pregnant women were at increased risk of LEE, highlighting the importance of close monitoring of toxicity biomarkers during pregnancy.
doi:10.7448/IAS.17.4.19486
PMCID: PMC4224861  PMID: 25393995
4.  Detection of resistance mutations and CD4 slopes in individuals experiencing sustained virological failure 
Journal of the International AIDS Society  2014;17(4Suppl 3):19737.
Introduction
Several resistance mutations have been shown to affect viral fitness, and the presence of certain mutations might result in clinical benefit for patients kept on a virologically failing regimen due to an exhaustion of drug options. We sought to quantify the effect of resistance mutations on CD4 slopes in patients undergoing episodes of viral failure.
Materials and Methods
Patients from the EuroSIDA and UK CHIC cohorts undergoing at least one episode of virological failure (>3 consecutive RNA measurements >500 on ART) with at least three CD4 measurements and a resistance test during the episode were included. Mutations were identified using the IAS-US (2013) list, and were presumed to be present from detection until the end of an episode. Multivariable linear mixed models with a random intercept and slope adjusted for age, baseline CD4 count, hepatitis C, drug type, RNA (log-scale), risk group and subtype were used to estimate CD4 slopes. Individual mutations with a population prevalence of >10% were tested for their effect on the CD4 slope.
Results
A total of 2731 patients experiencing a median of 1 (range 1–4) episodes were included in this analysis. The prevalence of any resistance per episode was 88.4%; NNRTI resistance was most common (78.5%). Overall, CD4 counts declined by 17.1 (−19.7; −14.5) cells per year; this decline was less marked with partial viral suppression (current HIV RNA more than 1.5 log below the setpoint; p=0.01). In multivariable models adjusting for viral load, CD4 decline was slower during episodes with detected resistance compared to episodes without detected resistance (21.0 cells/year less, 95% CI 11.75–30.31, p<0.001). Among those with more than one resistance mutation, there was only weak evidence that class-specific mutations had any effect on the CD4 slope (Table 1). The effects of individual mutations (incl. M184V) were explored, but none were significantly associated with the CD4 slope; for these comparisons, a Bonferroni-corrected p-value level was 0.003.
Conclusions
In our study population, detected resistance was associated with slightly less steep CD4 declines. This may be due to a biological effect of resistance on CD4 slopes, or other unmeasured factors such as poor adherence among individuals without resistance. Among individuals with detected drug resistance, we found no evidence suggesting that the presence of individual mutations was associated with beneficial CD4 slope changes.
doi:10.7448/IAS.17.4.19737
PMCID: PMC4225350  PMID: 25397482
5.  Cost-Effectiveness of HIV Drug Resistance Testing to Inform Switching to Second Line Antiretroviral Therapy in Low Income Settings 
PLoS ONE  2014;9(10):e109148.
Background
To guide future need for cheap resistance tests for use in low income settings, we assessed cost-effectiveness of drug resistance testing as part of monitoring of people on first line ART - with switching from first to second line ART being conditional on NNRTI drug resistance mutations being identified.
Methods
An individual level simulation model of HIV transmission, progression and the effect of ART which accounts for adherence and resistance development was used to compare outcomes of various potential monitoring strategies in a typical low income setting in sub-Saharan Africa. Underlying monitoring strategies considered were based on clinical disease, CD4 count or viral load. Within each we considered a strategy in which no further measures are performed, one with a viral load measure to confirm failure, and one with both a viral load measure and a resistance test. Predicted outcomes were assessed over 2015–2025 in terms of viral suppression, first line failure, switching to second line regimen, death, HIV incidence, disability-adjusted-life-years averted and costs. Potential future low costs of resistance tests ($30) were used.
Results
The most effective strategy, in terms of DALYs averted, was one using viral load monitoring without confirmation. The incremental cost-effectiveness ratio for this strategy was $2113 (the same as that for viral load monitoring with confirmation). ART monitoring strategies which involved resistance testing did not emerge as being more effective or cost effective than strategies not using it. The slightly reduced ART costs resulting from use of resistance testing, due to less use of second line regimens, was of similar magnitude to the costs of resistance tests.
Conclusion
Use of resistance testing at the time of first line failure as part of the decision whether to switch to second line therapy was not cost-effective, even though the test was assumed to be very inexpensive.
doi:10.1371/journal.pone.0109148
PMCID: PMC4188574  PMID: 25290340
6.  The Contribution of Viral Genotype to Plasma Viral Set-Point in HIV Infection 
PLoS Pathogens  2014;10(5):e1004112.
Disease progression in HIV-infected individuals varies greatly, and while the environmental and host factors influencing this variation have been widely investigated, the viral contribution to variation in set-point viral load, a predictor of disease progression, is less clear. Previous studies, using transmission-pairs and analysis of phylogenetic signal in small numbers of individuals, have produced a wide range of viral genetic effect estimates. Here we present a novel application of a population-scale method based in quantitative genetics to estimate the viral genetic effect on set-point viral load in the UK subtype B HIV-1 epidemic, based on a very large data set. Analyzing the initial viral load and associated pol sequence, both taken before anti-retroviral therapy, of 8,483 patients, we estimate the proportion of variance in viral load explained by viral genetic effects to be 5.7% (CI 2.8–8.6%). We also estimated the change in viral load over time due to selection on the virus and environmental effects to be a decline of 0.05 log10 copies/mL/year, in contrast to recent studies which suggested a reported small increase in viral load over the last 20 years might be due to evolutionary changes in the virus. Our results suggest that in the UK epidemic, subtype B has a small but significant viral genetic effect on viral load. By allowing the analysis of large sample sizes, we expect our approach to be applicable to the estimation of the genetic contribution to traits in many organisms.
Author Summary
HIV viral load, the amount of virus in the blood, is an important predictor of rate of CD4+ cell decline, time to AIDS and onwards transmission. Plasma viral load is influenced by many environmental and host factors, but the contribution of the viral genome is not yet clear. We have adapted a method from quantitative genetics which considers the viral phylogeny as a pedigree, permitting analysis of large cohort-derived datasets for the first time. We found the viral genome contributes significantly to the level of the set point viral load, but only determines about 6% of the variation in this property in this population. Our study also suggests that the change over time in mean plasma viral load described in some recent studies has not been due to a change in the component of viral load that is contributed by viral genotype.
doi:10.1371/journal.ppat.1004112
PMCID: PMC4006911  PMID: 24789308
7.  Cervicovaginal HIV-1 Shedding in Women Taking Antiretroviral Therapy in Burkina Faso: A Longitudinal Study 
Background:
Antiretroviral therapy (ART) reduces transmission of HIV-1. However, genital HIV-1 can be detected in patients on ART. We analyzed factors associated with genital HIV-1 shedding among high-risk women on ART in Burkina Faso.
Methods:
Plasma viral load (PVL) and enriched cervicovaginal lavage HIV-1 RNA were measured every 3–6 months for up to 8 years. Random-effects logistic and linear regression models were used to analyze associations of frequency and quantity of genital HIV-1 RNA with behavioral and biological factors, adjusting for within-woman correlation. The lower limit of detection of HIV-1 RNA in plasma and eCVL samples was 300 copies per milliliter.
Results:
One hundred and eighty-eight participants initiated ART from 2004 to 2011. PVL was detectable in 16% (171/1050) of visits, in 52% (90/174) of women. Cervicovaginal HIV-1 RNA was detectable in 16% (128/798) of visits with undetectable plasma HIV-1 RNA in 45% (77/170) of women. After adjusting for PVL, detectable cervicovaginal HIV-1 RNA was independently associated with abnormal vaginal discharge and use of nevirapine or zidovudine vs. efavirenz and stavudine, respectively; longer time on ART and hormonal contraception were not associated with increased shedding. The presence of bacterial vaginosis, herpes simplex virus-2 DNA, and the use of nevirapine vs efavirenz were independently associated with an increased quantity of cervicovaginal HIV-1 RNA.
Conclusions:
Certain ART regimens, abnormal vaginal discharge, bacterial vaginosis, and genital herpes simplex virus-2 are associated with HIV-1 cervicovaginal shedding or quantity in women on ART after adjusting for PVL. This may reduce the effectiveness of ART as prevention in high-risk populations.
doi:10.1097/QAI.0000000000000049
PMCID: PMC3979829  PMID: 24226060
antiretrovirals; HIV-1 RNA; cervicovaginal lavage; nevirapine; bacterial vaginosis; herpes simplex virus type-2
8.  High Level of Viral Suppression and Low Switch Rate to Second-Line Antiretroviral Therapy among HIV-Infected Adult Patients Followed over Five Years: Retrospective Analysis of the DART Trial 
PLoS ONE  2014;9(3):e90772.
In contrast to resource-rich countries, most HIV-infected patients in resource-limited countries receive treatment without virological monitoring. There are few long-term data, in this setting, on rates of viral suppression or switch to second-line antiretroviral therapy. The DART trial compared clinically driven monitoring (CDM) versus routine laboratory (CD4/haematology/biochemistry) and clinical monitoring (LCM) in HIV-infected adults initiating therapy. There was no virological monitoring in either study group during follow-up, but viral load was measured in Ugandan participants at trial closure. Two thousand three hundred and seventeen (2317) participants from this country initiated antiretroviral therapy with zidovudine/lamivudine plus tenofovir (n = 1717), abacavir (n = 300), or nevirapine (n = 300). Of 1896 (81.8%) participants who were alive and in follow-up at trial closure (median 5.1 years after therapy initiation), 1507 (79.5%) were on first-line and 389 (20.5%) on second-line antiretroviral therapy. The overall switch rate after the first year was 5.6 per 100 person-years; the rate was substantially higher in participants with low baseline CD4 counts (<50 cells/mm3). Among 1207 (80.1%) first-line participants with viral load measured, HIV RNA was <400 copies/ml in 963 (79.8%), 400–999 copies/ml in 37 (3.1%), 1,000–9,999 copies/ml in 110 (9.1%), and ≥10,000 copies/ml in 97 (8.0%). The proportion with HIV RNA <400 copies/ml was slightly lower (difference 7.1%, 95% CI 2.5 to 11.5%) in CDM (76.3%) than in LCM (83.4%). Among 252 (64.8%) second-line participants with viral load measured (median 2.3 years after switch), HIV RNA was <400 copies/ml in 226 (89.7%), with no difference between monitoring strategies. Low switch rates and high, sustained levels of viral suppression are achievable without viral load or CD4 count monitoring in the context of high-quality clinical care.
Trial Registration:
ISRCTN13968779
doi:10.1371/journal.pone.0090772
PMCID: PMC3953124  PMID: 24625508
9.  Response to antiretroviral therapy (ART): comparing women with previous use of zidovudine monotherapy (ZDVm) in pregnancy with ART naïve women 
BMC Infectious Diseases  2014;14:127.
Background
Short-term zidovudine monotherapy (ZDVm) remains an option for some pregnant HIV-positive women not requiring treatment for their own health but may affect treatment responses once antiretroviral therapy (ART) is subsequently started.
Methods
Data were obtained by linking two UK studies: the UK Collaborative HIV Cohort (UK CHIC) study and the National Study of HIV in Pregnancy and Childhood (NSHPC). Treatment responses were assessed for 2028 women initiating ART at least one year after HIV-diagnosis. Outcomes were compared using logistic regression, proportional hazards regression or linear regression.
Results
In adjusted analyses, ART-naïve (n = 1937) and ZDVm-experienced (n = 91) women had similar increases in CD4 count and a similar proportion achieving virological suppression; both groups had a low risk of AIDS.
Conclusions
In this setting, antenatal ZDVm exposure did not adversely impact on outcomes once ART was initiated for the woman’s health.
doi:10.1186/1471-2334-14-127
PMCID: PMC3995971  PMID: 24593018
HIV; Pregnancy; Antiretroviral therapy; United Kingdom
10.  Incomplete Reversibility of Estimated Glomerular Filtration Rate Decline Following Tenofovir Disoproxil Fumarate Exposure 
Jose, Sophie | Hamzah, Lisa | Campbell, Lucy J. | Hill, Teresa | Fisher, Martin | Leen, Clifford | Gilson, Richard | Walsh, John | Nelson, Mark | Hay, Phillip | Johnson, Margaret | Chadwick, David | Nitsch, Dorothea | Jones, Rachael | Sabin, Caroline A. | Post, Frank A. | Ainsworth, Jonathan | Anderson, Jane | Babiker, Abdel | Chadwick, David | Delpech, Valerie | Dunn, David | Fisher, Martin | Gazzard, Brian | Gilson, Richard | Gompels, Mark | Hay, Phillip | Hill, Teresa | Johnson, Margaret | Kegg, Stephen | Leen, Clifford | Nelson, Mark | Orkin, Chloe | Palfreeman, Adrian | Phillips, Andrew | Pillay, Deenan | Post, Frank | Sabin, Caroline | Sachikonye, Memory | Schwenk, Achim | Walsh, John | Hill, Teresa | Huntington, Susie | Josie, Sophie | Phillips, Andrew | Sabin, Caroline | Thornton, Alicia | Dunn, David | Glabay, Adam | Orkin, C. | Garrett, N. | Lynch, J. | Hand, J. | de Souza, C. | Fisher, M. | Perry, N. | Tilbury, S. | Churchill, D. | Gazzard, B. | Nelson, M. | Waxman, M. | Asboe, D. | Mandalia, S. | Delpech, V. | Anderson, J. | Munshi, S. | Korat, H. | Poulton, M. | Taylor, C. | Gleisner, Z. | Campbell, L. | Babiker, Abdel | Dunn, David | Glabay, Adam | Gilson, R. | Brima, N. | Williams, I. | Schwenk, A. | Ainsworth, J. | Wood, C. | Miller, S. | Johnson, M. | Youle, M. | Lampe, F. | Smith, C. | Grabowska, H. | Chaloner, C. | Puradiredja, D. | Walsh, J. | Weber, J. | Ramzan, F. | Mackie, N. | Winston, A. | Leen, C. | Wilson, A. | Gompels, M. | Allan, S. | Palfreeman, A. | Moore, A. | Chadwick, D. | Wakeman, K. | Kegg, Stephen | Main, Paul | Mitchell,  | Hunter,  | Sachikonye, Memory | Hay, Phillip | Dhillon, Mandip
The Journal of Infectious Diseases  2014;210(3):363-373.
Background. Tenofovir disoproxil fumarate (TDF) has been linked to renal impairment, but the extent to which this impairment is reversible is unclear. We aimed to investigate the reversibility of renal decline during TDF therapy.
Methods. Cox proportional hazards models assessed factors associated with discontinuing TDF in those with an exposure duration of >6 months. In those who discontinued TDF therapy, linear piecewise regression models estimated glomerular filtration rate (eGFR) slopes before initiation of, during, and after discontinuation of TDF therapy. Factors associated with not achieving eGFR recovery 6 months after discontinuing TDF were assessed using multivariable logistic regression.
Results. We observed declines in the eGFR during TDF exposure (mean slopes, −15.7 mL/minute/1.73 m2/year [95% confidence interval {CI}, −20.5 to −10.9] during the first 3 months and −3.1 mL/minute/1.73 m2/year [95% CI, −4.6 to −1.7] thereafter) and evidence of eGFR increases following discontinuation of TDF therapy (mean slopes, 12.5 mL/minute/1.73 m2/year [95% CI, 8.9–16.1] during the first 3 months and 0.8 mL/minute/1.73 m2/year [95% CI, .1–1.5] thereafter). Following TDF discontinuation, 38.6% of patients with a decline in the eGFR did not experience recovery. A higher eGFR at baseline, a lower eGFR after discontinuation of TDF therapy, and more-prolonged exposure to TDF were associated with an increased risk of incomplete recovery 6 months after discontinuation of TDF therapy.
Conclusions. This study shows that a decline in the eGFR during TDF therapy was not fully reversible in one third of patients and suggests that prolonged TDF exposure at a low eGFR should be avoided.
doi:10.1093/infdis/jiu107
PMCID: PMC4091582  PMID: 24585896
tenofovir; highly active antiretroviral therapy; eGFR; eGFR slopes; renal function; kidney
11.  Protease inhibitors effectively block cell-to-cell spread of HIV-1 between T cells 
Retrovirology  2013;10:161.
Background
The Human Immunodeficiency Virus type-1 (HIV-1) spreads by cell-free diffusion and by direct cell-to-cell transfer, the latter being a significantly more efficient mode of transmission. Recently it has been suggested that cell-to-cell spread may permit ongoing virus replication in the presence of antiretroviral therapy (ART) based on studies performed using Reverse Transcriptase Inhibitors (RTIs). Protease Inhibitors (PIs) constitute an important component of ART; however whether this class of inhibitors can suppress cell-to-cell transfer of HIV-1 is unexplored. Here we have evaluated the inhibitory effect of PIs during cell-to-cell spread of HIV-1 between T lymphocytes.
Results
Using quantitative assays in cell line and primary cell systems that directly measure the early steps of HIV-1 infection we find that the PIs Lopinavir and Darunavir are equally potent against both cell-free and cell-to-cell spread of HIV-1. We further show that a protease resistant mutant maintains its resistant phenotype during cell-to-cell spread and is transmitted more efficiently than wild-type virus in the presence of drug. By contrast we find that T cell-T cell spread of HIV-1 is 4–20 fold more resistant to inhibition by the RTIs Nevirapine, Zidovudine and Tenofovir. Notably, varying the ratio of infected and uninfected cells in co-culture impacted on the degree of inhibition, indicating that the relative efficacy of ART is dependent on the multiplicity of infection.
Conclusions
We conclude that if the variable effects of antiviral drugs on cell-to-cell virus dissemination of HIV-1 do indeed impact on viral replication and maintenance of viral reservoirs this is likely to be influenced by the antiviral drug class, since PIs appear particularly effective against both modes of HIV-1 spread.
doi:10.1186/1742-4690-10-161
PMCID: PMC3877983  PMID: 24364896
HIV-1; Virological synapse; Cell-cell spread; Protease inhibitor; ART
12.  High Rate of HIV Resuppression After Viral Failure on First-line Antiretroviral Therapy in the Absence of Switch to Second-line Therapy 
Gupta, Ravindra K. | Goodall, Ruth L. | Ranopa, Michael | Kityo, Cissy | Munderi, Paula | Lyagoba, Fred | Mugarura, Lincoln | Gilks, Charles F. | Kaleebu, Pontiano | Pillay, Deenan | Grosskurth, H. | Munderi, P. | Kabuye, G. | Nsibambi, D. | Kasirye, R. | Zalwango, E. | Nakazibwe, M. | Kikaire, B. | Nassuna, G. | Massa, R. | Fadhiru, K. | Namyalo, M. | Zalwango, A. | Generous, L. | Khauka, P. | Rutikarayo, N. | Nakahima, W. | Mugisha, A. | Todd, J. | Levin, J. | Muyingo, S. | Ruberantwari, A. | Kaleebu, P. | Yirrell, D. | Ndembi, N. | Lyagoba, F. | Hughes, P. | Aber, M. | Medina Lara, A. | Foster, S. | Amurwon, J. | Mugyenyi, P. | Kityo, C. | Ssali, F. | Tumukunde, D. | Otim, T. | Kabanda, J. | Musana, H. | Akao, J. | Kyomugisha, H. | Byamukama, A. | Sabiiti, J. | Komugyena, J. | Wavamunno, P. | Mukiibi, S. | Drasiku, A. | Byaruhanga, R. | Labeja, O. | Katundu, P. | Tugume, S. | Awio, P. | Namazzi, A. | Bakeinyaga, T. G. | Katabira, H. | Abaine, D. | Tukamushaba, J. | Anywar, W. | Ojiambo, W. | Angweng, E. | Murungi, S. | Haguma, W. | Atwiine, S. | Kigozi, J. | Latif, A. | Hakim, J. | Robertson, V. | Reid, A. | Chidziva, E. | Bulaya-Tembo, R. | Musoro, G. | Taziwa, F. | Chimbetete, C. | Chakonza, L. | Mawora, A. | Muvirimi, C. | Tinago, G. | Svovanapasis, P. | Simango, M. | Chirema, O. | Machingura, J. | Mutsai, S. | Phiri, M. | Bafana, T. | Chirara, M. | Muchabaiwa, L. | Muzambi, M. | Katabira, E. | Ronald, A. | Kambungu, A. | Lutwama, F. | Nanfuka, A. | Walusimbi, J. | Nabankema, E. | Nalumenya, R. | Namuli, T. | Kulume, R. | Namata, I. | Nyachwo, L. | Florence, A. | Kusiima, A. | Lubwama, E. | Nairuba, R. | Oketta, F. | Buluma, E. | Waita, R. | Ojiambo, H. | Sadik, F. | Wanyama, J. | Nabongo, P. | Ochai, R. | Muhweezi, D. | Gilks, C. | Boocock, K. | Puddephatt, C. | Winogron, D. | Bohannon, J. | Darbyshire, J. | Gibb, M. D. | Burke, A. | Bray, D. | Babiker, A. | Walker, S. A. | Wilkes, H. | Rauchenberger, M. | Sheehan, S. | Peto, L. | Taylor, K. | Spyer, M. | Ferrier, A. | Naidoo, B. | Dunn, D. | Goodall, R. | Nanfuka, R. | Mufuka-Kapuya, C. | Kaleebu, P. | Pillay, D. | Awio, P. | Chirara, M. | Dunn, D. | Gilks, C. | Goodall, R. | Kapaata, A. | Katuramur, M. | Lyagoba, F. | Magala, R. | Magambo, B. | Mataruka, K. | McCormick, A. | Mugarura, L. | Musunga, T. | Nabankkema, M. | Nkalubo, J. | Nkurunziza, P. | Parry, C. | Robertson, V. | Spyer, M. | Yirrell, D. | Medina Lara, A. | Foster, S. | Amurwon, J. | Nyanzi Wakholi, B. | Kigozi, J. | Muchabaiwa, L. | Muzambi, M. | Weller, I. | Babiker, A. | Bahendeka, S. | Bassett, M. | Chogo Wapakhabulo, A. | Darbyshire, J. | Gazzard, B. | Gilks, C. | Hakim, J. | Latif, A. | Mapuchere, C. | Mugurungi, O. | Mugyenyi, P. | Burke, C. | Jones, S. | Newland, C. | Rahim, S. | Rooney, J. | Smith, M. | Snowden, W. | Steens, J.-M. | Breckenridge, A. | McLaren, A. | Hill, C. | Matenga, J. | Pozniak, A. | Serwadda, D. | Peto, T. | Palfreeman, A. | Borok, M.
In a randomized comparison of nevirapine or abacavir with zidovudine plus lamivudine, routine viral load monitoring was not performed, yet 27% of individuals with viral failure at week 48 experienced resuppression by week 96 without switching. This supports World Health Organization recommendations that suspected viral failure should trigger adherence counseling and repeat measurement before a treatment switch is considered.
doi:10.1093/cid/cit933
PMCID: PMC3952602  PMID: 24352348
HIV; failure; viral resuppression; resistance; Africa
13.  The Immunological and Virological Consequences of Planned Treatment Interruptions in Children with HIV Infection 
PLoS ONE  2013;8(10):e76582.
Objectives
To evaluate the immunological and viral consequences of planned treatment interruptions (PTI) in children with HIV.
Design
This was an immunological and virological sub-study of the Paediatric European Network for Treatment of AIDS (PENTA) 11 trial, which compared CD4-guided PTI of antiretroviral therapy (ART) with continuous therapy (CT) in children.
Methods
HIV-1 RNA and lymphocyte subsets, including CD4 and CD8 cells, were quantified on fresh samples collected during the study; CD45RA, CD45RO and CD31 subpopulations were evaluated in some centres. For 36 (18 PTI, 18 CT) children, immunophenotyping was performed and cell-associated HIV-1 DNA analysed on stored samples to 48 weeks.
Results
In the PTI group, CD4 cell count fell rapidly in the first 12 weeks off ART, with decreases in both naïve and memory cells. However, the proportion of CD4 cells expressing CD45RA and CD45RO remained constant in both groups. The increase in CD8 cells in the first 12 weeks off ART in the PTI group was predominantly due to increases in RO-expressing cells. PTI was associated with a rapid and sustained increase in CD4 cells expressing Ki67 and HLA-DR, and increased levels of HIV-1 DNA.
Conclusions
PTI in children is associated with rapid changes in CD4 and CD8 cells, likely due to increased cell turnover and immune activation. However, children off treatment may be able to maintain stable levels of naïve CD4 cells, at least in proportion to the memory cell pool, which may in part explain the observed excellent CD4 cell recovery with re-introduction of ART.
doi:10.1371/journal.pone.0076582
PMCID: PMC3806774  PMID: 24194841
14.  Phylogenetic insights into regional HIV transmission 
AIDS (London, England)  2012;26(14):1813-1822.
Objectives
Despite prevention efforts new HIV diagnoses continue in the Southern US, where the epidemic is characterized by significant racial/ethnic disparities. We integrated phylogenetic analyses with clinical data to reveal trends in local HIV transmission.
Design
Cross-sectional analysis of 1671 HIV-infected individuals each with one B-subtype pol sequence obtained during chronic (82%; UNC Center for AIDS Research Clinical Cohort) or acute/recent (18%; Duke/UNC Acute HIV Consortium) infection.
Methods
Phylogenies were inferred using neighbor joining to select related sequences then confirmed with Bayesian methods. We characterized transmission clusters (clades n≥3 sequences supported by posterior probabilities=1) by factors including race/ethnicity and transmission risk. Factors associated with cluster membership were evaluated for newly diagnosed patients.
Results
Overall, 72% were male, 59% black and 39% MSM. A total of 557 (33%) sequences grouped in either 108 pairs (n=216) or 67 clusters (n=341). Clusters ranged from 3–36 (median 4) members. Composition was delineated primarily by race, with 28% exclusively black, and to a lesser extent by risk group. Both MSM and heterosexuals formed discrete clusters though substantial mixing was observed. In multivariable analysis, patients with age ≤30 years (P=0.009), acute infection (P=0.02), local residence (P=0.002), and transmitted drug resistance (P=0.02) were more likely to be cluster members while Latinos were less likely (P<0.001).
Conclusions
Integration of molecular, clinical and demographic data offers a unique view into the structure of local transmission networks. Clustering by black race, youth and TDR and inability to identify Latino clusters will inform prevention, testing and linkage to care strategies.
doi:10.1097/QAD.0b013e3283573244
PMCID: PMC3566771  PMID: 22739398
Molecular epidemiology; HIV transmission; Risk Factors; Acute Infection; Southeast US
15.  Phylodynamic and Phylogeographic Patterns of the HIV Type 1 Subtype F1 Parenteral Epidemic in Romania 
Abstract
In the late 1980s an HIV-1 epidemic emerged in Romania that was dominated by subtype F1. The main route of infection is believed to be parenteral transmission in children. We sequenced partial pol coding regions of 70 subtype F1 samples from children and adolescents from the PENTA-EPPICC network of which 67 were from Romania. Phylogenetic reconstruction using the sequences and other publically available global subtype F sequences showed that 79% of Romanian F1 sequences formed a statistically robust monophyletic cluster. The monophyletic cluster was epidemiologically linked to parenteral transmission in children. Coalescent-based analysis dated the origins of the parenteral epidemic to 1983 [1981–1987; 95% HPD]. The analysis also shows that the epidemic's effective population size has remained fairly constant since the early 1990s suggesting limited onward spread of the virus within the population. Furthermore, phylogeographic analysis suggests that the root location of the parenteral epidemic was Bucharest.
doi:10.1089/aid.2011.0390
PMCID: PMC3423652  PMID: 22251065
16.  Suppression of HBV by Tenofovir in HBV/HIV Coinfected Patients: A Systematic Review and Meta-Analysis 
PLoS ONE  2013;8(7):e68152.
Background
Hepatitis B coinfection is common in HIV-positive individuals and as antiretroviral therapy has made death due to AIDS less common, hepatitis has become increasingly important. Several drugs are available to treat hepatitis B. The most potent and the one with the lowest risk of resistance appears to be tenofovir (TDF). However there are several questions that remain unanswered regarding the use of TDF, including the proportion of patients that achieves suppression of HBV viral load and over what time, whether suppression is durable and whether prior treatment with other HBV-active drugs such as lamivudine, compromises the efficacy of TDF due to possible selection of resistant HBV strains.
Methods
A systematic review and meta-analysis following PRISMA guidelines and using multilevel mixed effects logistic regression, stratified by prior and/or concomitant use of lamivudine and/or emtricitabine.
Results
Data was available from 23 studies including 550 HBV/HIV coinfected patients treated with TDF. Follow up was for up to seven years but to ensure sufficient power the data analyses were limited to three years. The overall proportion achieving suppression of HBV replication was 57.4%, 79.0% and 85.6% at one, two and three years, respectively. No effect of prior or concomitant 3TC/FTC was shown. Virological rebound on TDF treatment was rare.
Interpretation
TDF suppresses HBV to undetectable levels in the majority of HBV/HIV coinfected patients with the proportion fully suppressed continuing to increase during continuous treatment. Prior treatment with 3TC/FTC does not compromise efficacy of TDF treatment. The use of combination treatment with 3TC/FTC offers no significant benefit over TDF alone.
doi:10.1371/journal.pone.0068152
PMCID: PMC3707972  PMID: 23874527
17.  Universal Amplification, Next-Generation Sequencing, and Assembly of HIV-1 Genomes 
Journal of Clinical Microbiology  2012;50(12):3838-3844.
Whole HIV-1 genome sequences are pivotal for large-scale studies of inter- and intrahost evolution, including the acquisition of drug resistance mutations. The ability to rapidly and cost-effectively generate large numbers of HIV-1 genome sequences from different populations and geographical locations and determine the effect of minority genetic variants is, however, a limiting factor. Next-generation sequencing promises to bridge this gap but is hindered by the lack of methods for the enrichment of virus genomes across the phylogenetic breadth of HIV-1 and methods for the robust assembly of the virus genomes from short-read data. Here we report a method for the amplification, next-generation sequencing, and unbiased de novo assembly of HIV-1 genomes of groups M, N, and O, as well as recombinants, that does not require prior knowledge of the sequence or subtype. A sensitivity of at least 3,000 copies/ml was determined by using plasma virus samples of known copy numbers. We applied our novel method to compare the genome diversities of HIV-1 groups, subtypes, and genes. The highest level of diversity was found in the env, nef, vpr, tat, and rev genes and parts of the gag gene. Furthermore, we used our method to investigate mutations associated with HIV-1 drug resistance in clinical samples at the level of the complete genome. Drug resistance mutations were detected as both major variant and minor species. In conclusion, we demonstrate the feasibility of our method for large-scale HIV-1 genome sequencing. This will enable the phylogenetic and phylodynamic resolution of the ongoing pandemic and efficient monitoring of complex HIV-1 drug resistance genotypes.
doi:10.1128/JCM.01516-12
PMCID: PMC3502977  PMID: 22993180
18.  Full-Genome Deep Sequencing and Phylogenetic Analysis of Novel Human Betacoronavirus 
Emerging Infectious Diseases  2013;19(5):736-742.
A novel betacoronavirus associated with lethal respiratory and renal complications was recently identified in patients from several countries in the Middle East. We report the deep genome sequencing of the virus directly from a patient’s sputum sample. Our high-throughput sequencing yielded a substantial depth of genome sequence assembly and showed the minority viral variants in the specimen. Detailed phylogenetic analysis of the virus genome (England/Qatar/2012) revealed its close relationship to European bat coronaviruses circulating among the bat species of the Vespertilionidae family. Molecular clock analysis showed that the 2 human infections of this betacoronavirus in June 2012 (EMC/2012) and September 2012 (England/Qatar/2012) share a common virus ancestor most likely considerably before early 2012, suggesting the human diversity is the result of multiple zoonotic events.
doi:10.3201/eid1905.130057
PMCID: PMC3647518  PMID: 23693015
disease transmission; infectious; coronavirus infections; evolution; molecular; respiratory tract infections; high-throughput nucleotide sequencing; computer-aided design; viruses; zoonoses
19.  HIV Type 1 in a Rural Coastal Town in Kenya Shows Multiple Introductions with Many Subtypes and Much Recombination 
Abstract
The extent of HIV-1 diversity was examined among patients attending a rural district hospital in a coastal area of Kenya. The pol gene was sequenced in samples from 153 patients. Subtypes were designated using the REGA, SCUEAL, and jpHMM programs. The most common subtype was A1, followed by C and D; A2 and G were also detected. However, a large proportion of the samples was found to be recombinants, which clustered within the pure subtype branches. Phylogeographic analysis of Kilifi sequences compared with those from other regions of Africa showed that while many sequences were closely related to sequences from Kenya, others were most closely related to known sequences from other parts of Africa, including West Africa. Overall, these data indicate that there have been multiple introductions of HIV-1 into this small rural town and surroundings with ongoing diversity being generated by recombination.
doi:10.1089/aid.2011.0048
PMCID: PMC3275924  PMID: 21770741
20.  Predictors of pregnancy and changes in pregnancy incidence among HIV-positive women accessing HIV clinical care at 13 large UK clinics 
AIDS (London, England)  2013;27(1):95-103.
Objectives
To describe predictors of pregnancy and changes in pregnancy incidence among HIV-positive women accessing HIV clinical care.
Methods
Data were obtained through the linkage of two separate studies; the UK Collaborative HIV Cohort study (UK CHIC), a cohort of adults attending 13 large HIV clinics, and the National Study of HIV in Pregnancy and Childhood (NSHPC), a national surveillance study of HIV-positive pregnant women. Pregnancy incidence was measured using the proportion of women in UK CHIC with a pregnancy reported to NSHPC. Generalised estimating equations were used to identify predictors of pregnancy and assess changes in pregnancy incidence in 2000-2009.
Results
The number of women accessing care at UK CHIC sites increased as did the number of pregnancies (from 72 to 230). Older women were less likely to have a pregnancy (adjusted Relative Rate (aRR) 0.44 per 10 year increment in age [95% CI [0.41-0.46], p<0.001) as were women with CD4<200 cells/mm3 compared with CD4 200-350 cells/mm3 (aRR 0.65 [0.55-0.77] p<0.001) and women of white ethnicity compared with women of black-African ethnicity (aRR 0.67 [0.57-0.80], p<0.001). The likelihood that women had a pregnancy increased over the study period (aRR 1.05 [1.03-1.07], p<0.001). The rate of change did not significantly differ according to age group, ART use, CD4 group or ethnicity.
Conclusions
The pregnancy rate among women accessing HIV clinical care increased in 2000-2009. HIV-positive women with, or planning, a pregnancy require a high level of care and this is likely to continue and increase as more women of older age have pregnancies.
doi:10.1097/QAD.0b013e3283565df1
PMCID: PMC3495056  PMID: 22713479
HIV; pregnancy; pregnancy rate; maternal age; highly active antiretroviral therapy; maternal-fetal infection transmission; United Kingdom
21.  Hepatitis B Virus Infection in HIV-Positive Individuals in the UK Collaborative HIV Cohort (UK CHIC) Study 
PLoS ONE  2012;7(11):e49314.
Background
Hepatitis B virus (HBV) infection is an increasingly important cause of morbidity and mortality in HIV-infected adults. This study aimed to determine the prevalence and incidence of HBV in the UK CHIC Study, a multicentre observational cohort.
Methods and Findings
12 HIV treatment centres were included. Of 37,331 patients, 27,450 had at least one test (HBsAg, anti-HBs or anti-HBc) result post-1996 available. 16,043 were white, 8,130 black and 3,277 other ethnicity. Route of exposure was homosexual sex 15,223 males, heterosexual sex 3,258 males and 5,384 females, injecting drug use 862 and other 2,723. The main outcome measures used were the cumulative prevalence and the incidence of HBV coinfection. HBV susceptible patients were followed up until HBsAg and/or anti-HBc seroconversion incident infection, evidence of vaccination or last visit. Poisson regression was used to determine associated factors. 25,973 had at least one HBsAg test result. Participants with HBsAg results were typically MSM (57%) and white (59%) (similar to the cohort as a whole). The cumulative prevalence of detectable HBsAg was 6.9% (6.6 to 7.2%). Among the 3,379 initially HBV-susceptible patients, the incidence of HBV infection was 1.7 (1.5 to 1.9)/100 person-years. Factors associated with incident infection were older age and IDU. The main limitation of the study was that 30% of participants did not have any HBsAg results available. However baseline characteristics of those with results did not differ from those of the whole cohort. Efforts are on-going to improve data collection.
Conclusions
The prevalence of HBV in UK CHIC is in line with estimates from other studies and low by international standards. Incident infection continued to occur even after entry to the cohort, emphasising the need to ensure early vaccination.
doi:10.1371/journal.pone.0049314
PMCID: PMC3492264  PMID: 23145150
22.  Global trends in antiretroviral resistance in treatment-naive individuals with HIV after rollout of antiretroviral treatment in resource-limited settings: a global collaborative study and meta-regression analysis 
Lancet  2012;380(9849):1250-1258.
Summary
Background
The emergence and spread of high levels of HIV-1 drug resistance in resource-limited settings where combination antiretroviral treatment has been scaled up could compromise the effectiveness of national HIV treatment programmes. We aimed to estimate changes in the prevalence of HIV-1 drug resistance in treatment-naive individuals with HIV since initiation of rollout in resource-limited settings.
Methods
We did a systematic search for studies and conference abstracts published between January, 2001, and July, 2011, and included additional data from the WHO HIV drug resistance surveillance programme. We assessed the prevalence of drug-resistance mutations in untreated individuals with respect to time since rollout in a series of random-effects meta-regression models.
Findings
Study-level data were available for 26 102 patients from sub-Saharan Africa, Asia, and Latin America. We recorded no difference between chronic and recent infection on the prevalence of one or more drug-resistance mutations for any region. East Africa had the highest estimated rate of increase at 29% per year (95% CI 15 to 45; p=0·0001) since rollout, with an estimated prevalence of HIV-1 drug resistance at 8 years after rollout of 7·4% (4·3 to 12·7). We recorded an annual increase of 14% (0% to 29%; p=0·054) in southern Africa and a non-significant increase of 3% (–0·9 to 16; p=0·618) in west and central Africa. There was no change in resistance over time in Latin America, and because of much country-level heterogeneity the meta-regression analysis was not appropriate for Asia. With respect to class of antiretroviral, there were substantial increases in resistance to non-nucleoside reverse transcriptase inhibitors (NNRTI) in east Africa (36% per year [21 to 52]; p<0·0001) and southern Africa (23% per year [7 to 42]; p=0·0049). No increase was noted for the other drug classes in any region.
Interpretation
Our findings suggest a significant increase in prevalence of drug resistance over time since antiretroviral rollout in regions of sub-Saharan Africa; this rise is driven by NNRTI resistance in studies from east and southern Africa. The findings are of concern and draw attention to the need for enhanced surveillance and drug-resistance prevention efforts by national HIV treatment programmes. Nevertheless, estimated levels, although increasing, are not unexpected in view of the large expansion of antiretroviral treatment coverage seen in low-income and middle-income countries—no changes in antiretroviral treatment guidelines are warranted at the moment.
Funding
Bill & Melinda Gates Foundation and the European Community's Seventh Framework Programme
doi:10.1016/S0140-6736(12)61038-1
PMCID: PMC3790969  PMID: 22828485
23.  Treatment switches during pregnancy among HIV-positive women on antiretroviral therapy at conception 
AIDS (London, England)  2011;25(13):1647-1655.
Objectives
To describe antiretroviral therapy (ART) use and clinical status, at start of and during pregnancy, for HIV-positive women receiving ART at conception, including the proportion conceiving on drugs (efavirenz and didanosine) not recommended for use in early pregnancy.
Methods
Women with a pregnancy resulting in a live birth after 1995 (n=1,537) were identified in an observational cohort of patients receiving HIV care at 12 clinics in the UK by matching records with national pregnancy study data. Treatment and clinical data were analysed for 375 women conceiving on ART, including logistic regression to identify factors associated with changing regimen during pregnancy.
Results
Of the 375 women on ART at conception, 39 (10%) conceived on dual therapy, 306 (82%) on triple therapy and 30 (8%) on >3 drugs. In total, 116 (31%) women conceived on a regimen containing efavirenz or didanosine (69 efavirenz, 54 didanosine, 7 both). Overall, 38% (143) switched regimen during pregnancy, of whom 41% (n=48) had a detectable viral load (≥50 copies/ml) around that time. Detectable viral load was associated with increased risk of regimen change (adjusted odds ratio 2.2, 95% confidence interval [1.3, 3.8]), while women on efavirenz at conception were three times more likely to switch than women on other drugs (3.3, [1.8, 6.0]). Regimen switching was also associated with calendar year at conception (0.9, [0.8-1.0]).
Conclusions
These findings reinforce the need for careful consideration of ART use among women planning or likely to have a pregnancy in order to reduce viral load before pregnancy and avoid drugs not recommended for early antenatal use.
doi:10.1097/QAD.0b013e32834982af
PMCID: PMC3428898  PMID: 21673558
HIV; pregnancy; antiretroviral agents; antiretroviral therapy; United Kingdom
24.  Cost-Effectiveness of Tenofovir Instead of Zidovudine for Use in First-Line Antiretroviral Therapy in Settings without Virological Monitoring 
PLoS ONE  2012;7(8):e42834.
Background
The most recent World Health Organization (WHO) antiretroviral treatment guidelines recommend the inclusion of zidovudine (ZDV) or tenofovir (TDF) in first-line therapy. We conducted a cost-effectiveness analysis with emphasis on emerging patterns of drug resistance upon treatment failure and their impact on second-line therapy.
Methods
We used a stochastic simulation of a generalized HIV-1 epidemic in sub-Saharan Africa to compare two strategies for first-line combination antiretroviral treatment including lamivudine, nevirapine and either ZDV or TDF. Model input parameters were derived from literature and, for the simulation of resistance pathways, estimated from drug resistance data obtained after first-line treatment failure in settings without virological monitoring. Treatment failure and cost effectiveness were determined based on WHO definitions. Two scenarios with optimistic (no emergence; base) and pessimistic (extensive emergence) assumptions regarding occurrence of multidrug resistance patterns were tested.
Results
In the base scenario, cumulative proportions of treatment failure according to WHO criteria were higher among first-line ZDV users (median after six years 36% [95% simulation interval 32%; 39%]) compared with first-line TDF users (31% [29%; 33%]). Consequently, a higher proportion initiated second-line therapy (including lamivudine, boosted protease inhibitors and either ZDV or TDF) in the first-line ZDV user group 34% [31%; 37%] relative to first-line TDF users (30% [27%; 32%]). At the time of second-line initiation, a higher proportion (16%) of first-line ZDV users harboured TDF-resistant HIV compared with ZDV-resistant viruses among first-line TDF users (0% and 6% in base and pessimistic scenarios, respectively). In the base scenario, the incremental cost effectiveness ratio with respect to quality adjusted life years (QALY) was US$83 when TDF instead of ZDV was used in first-line therapy (pessimistic scenario: US$ 315), which was below the WHO threshold for high cost effectiveness (US$ 2154).
Conclusions
Using TDF instead of ZDV in first-line treatment in resource-limited settings is very cost-effective and likely to better preserve future treatment options in absence of virological monitoring.
doi:10.1371/journal.pone.0042834
PMCID: PMC3414499  PMID: 22905175
25.  Using two on-going HIV studies to obtain clinical data from before, during and after pregnancy for HIV-positive women 
Background
The UK Collaborative HIV Cohort (UK CHIC) is an observational study that collates data on HIV-positive adults accessing HIV clinical care at (currently) 13 large clinics in the UK but does not collect pregnancy specific data. The National Study of HIV in Pregnancy and Childhood (NSHPC) collates data on HIV-positive women receiving antenatal care from every maternity unit in the UK and Ireland. Both studies collate pseudonymised data and neither dataset contains unique patient identifiers. A methodology was developed to find and match records for women reported to both studies thereby obtaining clinical and treatment data on pregnant HIV-positive women not available from either dataset alone.
Results
Women in UK CHIC receiving HIV-clinical care in 1996–2009, were found in the NSHPC dataset by initially ‘linking’ records with identical date-of-birth, linked records were then accepted as a genuine ‘match’, if they had further matching fields including CD4 test date. In total, 2063 women were found in both datasets, representing 23.1% of HIV-positive women with a pregnancy in the UK (n = 8932). Clinical data was available in UK CHIC following most pregnancies (92.0%, 2471/2685 pregnancies starting before 2009). There was bias towards matching women with repeat pregnancies (35.9% (741/2063) of women found in both datasets had a repeat pregnancy compared to 21.9% (1502/6869) of women in NSHPC only) and matching women HIV diagnosed before their first reported pregnancy (54.8% (1131/2063) compared to 47.7% (3278/6869), respectively).
Conclusions
Through the use of demographic data and clinical dates, records from two independent studies were successfully matched, providing data not available from either study alone.
doi:10.1186/1471-2288-12-110
PMCID: PMC3475121  PMID: 22839414
Data linkage; HIV; Pregnant women; Antiretroviral therapy; Cohort analysis; United Kingdom

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