We investigated immune determinants of antibody responses and B-cell memory to pH1N1 vaccine in HIV-infected children.
Ninety subjects 4 to <25 years of age received two double doses of pH1N1 vaccine. Serum and cells were frozen at baseline, after each vaccination, and at 28 weeks post-immunization. Hemagglutination inhibition (HAI) titers, avidity indices (AI), B-cell subsets, and pH1N1 IgG and IgA antigen secreting cells (ASC) were measured at baseline and after each vaccination. Neutralizing antibodies and pH1N1-specific Th1, Th2 and Tfh cytokines were measured at baseline and post-dose 1.
At entry, 26 (29%) subjects had pH1N1 protective HAI titers (≥1:40). pH1N1-specific HAI, neutralizing titers, AI, IgG ASC, IL-2 and IL-4 increased in response to vaccination (p<0.05), but IgA ASC, IL-5, IL-13, IL-21, IFNγ and B-cell subsets did not change. Subjects with baseline HAI ≥1:40 had significantly greater increases in IgG ASC and AI after immunization compared with those with HAI <1:40. Neutralizing titers and AI after vaccination increased with older age. High pH1N1 HAI responses were associated with increased IgG ASC, IFNγ, IL-2, microneutralizion titers, and AI. Microneutralization titers after vaccination increased with high IgG ASC and IL-2 responses. IgG ASC also increased with high IFNγ responses. CD4% and viral load did not predict the immune responses post-vaccination, but the B-cell distribution did. Notably, vaccine immunogenicity increased with high CD19+CD21+CD27+% resting memory, high CD19+CD10+CD27+% immature activated, low CD19+CD21-CD27-CD20-% tissue-like, low CD19+CD21-CD27-CD20-% transitional and low CD19+CD38+HLADR+% activated B-cell subsets.
HIV-infected children on HAART mount a broad B-cell memory response to pH1N1 vaccine, which was higher for subjects with baseline HAI≥1:40 and increased with age, presumably due to prior exposure to pH1N1 or to other influenza vaccination/infection. The response to the vaccine was dependent on B-cell subset distribution, but not on CD4 counts or viral load.
Multiple studies have shown excellent response rates after hepatitis B immunization in youth; however, one previous study conducted in urban youth demonstrated poor responses.
Urban youth, ages 12-17 years, at participating Adolescent Medicine Trials Network for HIV/AIDS Interventions Clinical/Research (ATN) sites were randomized to receive either two doses of Recombivax HB (10mcg hepatitis B surface antigen) or Twinrix (20mcg hepatitis B surface antigen and 720 EL.U hepatitis A antigen) at 0 and 24 weeks. Safety data were collected and antibody measures performed at 0, 28 and 76 weeks.
123 subjects were enrolled and 102 had week 28 serum samples available for antibody measure. A positive response (serum antibody ≥ 10mIU/mL) to hepatitis B antigen was documented in 41/47 (87.2%; 95% confidence interval (CI) 74.3%-95.2%) Recombivax HB recipients and in 52/55 (94.6%; 95% CI 84.9%-98.9%) Twinrix recipients (p=.295). In an adjusted analysis, those identified as Hispanic ethnicity (N=86) were more likely to have a positive response (odds ratio 7.38, 95% confidence interval 1.56-34.95; p=0.0018); whereas those who identified as not heterosexual (N=9) were less likely to respond (odds ratio=0.12, 95%CI, 0.02-0.74). The majority of youth in the Twinrix arm were hepatitis A antibody positive at baseline (26/51; 51%); however, 24/25 hepatitis A antibody negative youth responded to the hepatitis A component. Both vaccines were safe.
Response rate to two doses of Recombivax HB in urban youth is lower than previous studies suggest. The factors associated with diminished response are not known.
Adolescents; hepatitis B; Vaccination; Immunogenicity
The World Health Organization (WHO) has recommended the use of clinical staging alone and with total lymphocyte count to identify HIV infected children in need of antiretroviral therapy (ART) in resource-limited settings, when CD4 cell count is not available.
We prospectively enrolled children obtaining care for HIV infection at the Kilimanjaro Christian Medical Centre Pediatric Infectious Diseases Clinic in Moshi, Tanzania between March 2004 and May 2006 for this cohort study.
192 (89.7%) of 214 children met WHO ART initiation criteria based on clinical staging or CD4 cell count. Several low-cost measures identified individuals who met WHO ART initiation criteria to the following degree: WHO stages 3 or 4 had 87.5% (95% CI; 82.8 – 92.1) sensitivity and, by definition, 100% (CI; 100 – 100) specificity; WHO recommended advance disease TLC cutoffs: sensitivity = 23.9% (95% CI; 17.3 – 30.5) specificity = 78.2% (95% CI: 67.3 – 89.1). Low TLC was a common finding, (50/214; 23%); however, it did not improve the sensitivity or specificity of clinical staging in identifying the severely immunosuppressed stage 2 children. Growth failure or use of total lymphocyte counts in isolation were not reliable indicators of severe immunosuppression or need to initiate ART.
The use of total lymphocyte count does not improve the ability to identify children in need of ART compared to clinical staging alone. Low absolute lymphocyte count did not correlate with severe immunosuppression based on CD4 cell count in this cohort.
HIV/AIDS; ART; TLC; pediatrics; immunosuppression; CD4
The highest incidence of childhood acute lower respiratory tract infection (ALRI) is in low- and middle-income countries. Few studies examined whether detection of respiratory viruses predicts ALRI outcomes in these settings.
We conducted prospective cohort and case-control studies of children 1-23 months of age in Botswana. Cases met clinical criteria for pneumonia and were recruited within six hours of presentation to a referral hospital. Controls were children without pneumonia matched to cases by primary care clinic and date of enrollment. Nasopharyngeal specimens were tested for respiratory viruses using polymerase chain reaction. We compared detection rates of specific viruses in matched case-control pairs. We examined the effect of respiratory syncytial virus (RSV) and other respiratory viruses on pneumonia outcomes.
Between April 2012 and August 2014, we enrolled 310 cases, of which 133 had matched controls. Median ages of cases and controls were 6.1 and 6.4 months, respectively. One or more viruses were detected from 75% of cases and 34% of controls. RSV and human metapneumovirus were more frequent among cases than controls, but only enterovirus/rhinovirus was detected from asymptomatic controls. Compared with non-RSV viruses, RSV was associated with an increased risk of treatment failure at 48 hours [risk ratio (RR): 1.85; 95% confidence interval (CI): 1.20, 2.84], more days of respiratory support [mean difference (MD): 1.26 days; 95% CI: 0.30, 2.22 days], and longer duration of hospitalization [MD: 1.35 days; 95% CI: 0.20, 2.50 days], but lower in-hospital mortality [RR: 0.09; 95% CI: 0.01, 0.80] in children with pneumonia.
Respiratory viruses were detected from most children hospitalized with ALRI in Botswana, but only RSV and human metapneumovirus were more frequent than among children without ALRI. Detection of RSV from children with ALRI predicted a protracted illness course but lower mortality compared with non-RSV viruses.
Human herpesvirus 8 (HHV-8), also known as Kaposi's sarcoma (KS)–associated herpesvirus, is the etiologic agent responsible for all types of KS. Although the majority of pediatric KS cases occur in sub-Saharan Africa, a rise in pediatric transplant KS has been reported in developed countries. In addition, HHV-8 is increasingly described as an infectious cause of hemophagocytic lymphohistiocytosis in children. Transmission of HHV-8 among children is poorly understood; however, the literature strongly suggests that horizontal transmission plays a critical role. Acute infection with HHV-8 and progression to KS in children may be different than in adults, and diagnosis may be overlooked. Currently, neither adult nor pediatric treatment guidelines exist. This review provides an overview of HHV-8 disease in children as it relates to epidemic KS, transplant KS, and other disease manifestations. The current state of the literature is reviewed and knowledge gaps are identified for future exploration.
children; HHV-8; HIV; Kaposi's sarcoma; KSHV
With the emergence of pandemic influenza A (pH1N1) in 2009, children and youth infected with human immunodeficiency virus (HIV) were vulnerable because of immunologic impairment and the greater virulence of this infection in young persons.
A multicenter study of the immunogenicity of 3 licensed influenza A (H1N1) monovalent vaccines (1 live attenuated and 2 inactivated) was conducted in children and youth with perinatal HIV infection, most of whom were receiving ≥3 antiretroviral drugs, had CD4% ≥15, and plasma HIV RNA levels <400 copies/mL. Serum hemagglutinin inhibition assay (HAI) antibody levels were measured and correlated with baseline demographic and clinical variables.
One hundred forty-nine subjects were enrolled at 26 sites in the United States and Puerto Rico. Over 40% had baseline HAI titers ≥40. For subjects aged 6 months to <10 years, 79% and 68%, respectively, achieved a ≥40- and ≥4-fold rise in HAI titers after the second dose of vaccine. Three weeks after a single immunization with an inactivated vaccine, similar immunogenicity results were achieved in youth aged 10–24 years. With multivariable analysis, only Hispanic ethnicity and CD4% ≥15 were associated with achieving both HAI titer ≥40- and ≥4-fold rise in titer.
Although licensed pH1N1 vaccines produced HAI titers that were considered to be protective in the majority of HIV-infected children and youth, the proportion with titers ≥40- and ≥4-fold rise in titer was lower than expected for children without HIV infection. Vaccine immunogenicity was lower in HIV-infected children and youth with evidence of immune suppression.
Data on human immunodeficiency virus (HIV) and hepatitis B virus (HBV) and hepatitis C virus (HCV) coinfection among children in Africa are limited. We evaluated the seroprevalence of both viruses among healthy, HIV-uninfected children and HIV-infected children in the Kilimanjaro region of northern Tanzania.
HBV and HCV markers were assessed using serum and plasma samples from HIV-negative children ages 1 month to 18 years, recruited primarily from 2 hospital vaccination clinics; and HIV-infected children 1–16 years of age, enrolled in care and on highly active antiretroviral therapy (HAART). HBV markers included hepatitis B surface antigen (HBsAg), hepatitis B surface antibody, and hepatitis B core antibody (HBcAb). Evidence of any prior HBV infection was defined as a single positive HBsAg or HBcAb result; presumed chronic hepatitis B infection was defined as a single positive HBsAg result. HCV infection was assessed by anti-HCV enzyme-linked immunosorbent assay.
Samples from 547 children were tested. Of 157 children infected with HIV, 9.6% (95% CI: 4.9, 14.2) showed evidence of any HBV infection, compared to 2.1% (95% CI: .6, 3.5) of HIV-negative children. Children with HIV were much more likely to show evidence of HBV infection than children without HIV (odds ratio [OR] = 5.0, P < .0001). Prevalence of presumed chronic HBV infection was 2.9% (95% CI: 1.5, 4.3) overall. Again, prevalence was higher among HIV-infected children (7.0% [95% CI: 3.0, 11.0]) compared to HIV-negative children (1.3% [95% CI: .2, 2.4]; OR = 5.8 [P = .0003]). Of 546 samples tested for anti-HCV antibody, none were positive.
HBV seroprevalence is high among children in the Kilimanjaro Region, with a significantly higher prevalence among children who are infected with HIV. Routine screening for HBV is needed among HIV-infected children. Patients with coinfection require closer monitoring of liver transaminases due to potential for hepatic toxicities, and they may need HAART regimens that will target both viruses. Guidelines for the management of coinfected children are urgently needed.
HIV; Hepatitis B; Hepatitis C; Children; Sub-Saharan Africa
Human parainfluenza virus type 3 (HPIV3) is a common cause of upper and lower respiratory tract illness in infants and young children. Live-attenuated cold-adapted HPIV3 vaccines have been evaluated in infants but a suitable interval for administration of a second dose of vaccine has not been defined.
HPIV3-seronegative children between the ages of 6 and 36 months were randomized 2:1 in a blinded study to receive two doses of 105 TCID50 (50% tissue culture infectious dose) of live-attenuated, recombinant cold-passaged human PIV3 vaccine (rHPIV3cp45) or placebo 6 months apart. Serum antibody levels were assessed prior to and approximately 4-6 weeks after each dose. Vaccine virus infectivity, defined as detection of vaccine-HPIV3 in nasal wash and/or a ≥ 4-fold rise in serum antibody titer, and reactogenicity were assessed on days 3, 7, and 14 following immunization.
Forty HPIV3-seronegative children (median age 13 months; range 6-35 months) were enrolled; 27 (68%) received vaccine and 13 (32%) received placebo. Infectivity was detected in 25 (96%) of 26 evaluable vaccinees following dose 1 and 9 of 26 subject (35%) following dose 2. Among those who shed virus, the median duration of viral shedding was 12 days (range, 6-15 days) after dose 1 and 6 days (range 3-8 days) after dose 2, with a mean peak log10 viral titer of 3.4 PFU/mL (SD: 1.0) after dose 1 compared to1.5 PFU/mL (SD: 0.92) after dose 2. Overall, reactogenicity was mild, with no difference in rates of fever and upper respiratory infection symptoms between vaccine and placebo groups.
rHPIV3cp45 was immunogenic and well-tolerated in seronegative young children. A second dose administered 6 months after the initial dose was restricted in those previously infected with vaccine virus; however, the second dose boosted antibody responses and induced antibody responses in two previously uninfected children.
Parainfluenza; Live-attenuated vaccine; Recombinant virus vaccine; Pediatric vaccine
In Tanzania, HIV-1 RNA testing is rarely available and not standard of care. Determining virologic failure is challenging and resistance mutations accumulate, thereby compromising second-line therapy. We evaluated durability of antiretroviral therapy (ART) and predictors of virologic failure among a pediatric cohort at four-year follow-up.
This was a prospective cross-sectional study with retrospective chart review evaluating a perinatally HIV-infected Tanzanian cohort enrolled in 2008-09 with repeat HIV-1 RNA in 2012-13. Demographic, clinical, and laboratory data were extracted from charts, resistance mutations from 2008-9 were analyzed, and prospective HIV RNA was obtained.
161 (78%) participants of the original cohort consented to repeat HIV RNA. The average age was 12.2 years (55% adolescents ≥12 years). Average time on ART was 6.4 years with 41% receiving second-line (protease inhibitor based) therapy. Among those originally suppressed on a first-line (non-nucleoside reverse transcriptase based regimen) 76% remained suppressed. Of those originally failing first-line, 88% were switched to second-line and 72% have suppressed virus. Increased level of viremia and duration of ART trended with an increased number of thymidine analogue mutations (TAMs). Increased TAMs increased the odds of virologic failure (p = 0.18), as did adolescent age (p < 0.01).
After viral load testing in 2008-09 many participants switched to second-line therapy. The majority achieved virologic suppression despite multiple resistance mutations. Though virologic testing would likely hasten the switch to second-line among those failing, methods to improve adherence is critical to maximize durability of ART and improve virologic outcomes among youth in resource-limited settings.
Pediatric HIV; HIV resistance; Thymidine analogue mutations; ART adherence; HIV RNA; Durability of antiretroviral therapy; Viral load
Many HIV care and treatment programs in resource-limited settings rely on clinical and immunologic monitoring of antiretroviral therapy (ART), but accuracy of this strategy to detect virologic failure (VF) among children has not been evaluated.
A cross sectional sample of HIV-infected children aged 1-16 years on ART ≥6 months receiving care at a Tanzanian referral center underwent clinical staging, CD4 lymphocyte measurement, plasma HIV-1 RNA level, and complete blood count (CBC). Associations with VF (HIV RNA ≥400 copies/mL) were determined utilizing bivariable and multivariate analyses; accuracy of current clinical and immunologic guidelines in identifying children with VF was assessed.
Of 206 children (median age 8.7 years, ART duration 2.4 years), 65 (31.6%) demonstrated VF at enrollment. Clinical and immunological criteria identified 2 (3.5%) of 57 children with VF on first-line therapy, exhibiting 3.5% sensitivity and 100% specificity. VF was associated with younger age, receipt of nevirapine vs. efavirenz-based regimen, CD4% <25%, and physician documentation of maladherence (p<0.05 on bivariable analysis); the latter two factors remained significant on multivariate logistic regression.
This study demonstrates poor performance of clinical and immunologic criteria in identifying children with virologic failure. Affordable techniques for measuring HIV-1 RNA level applicable in resource-limited settings are urgently needed.
HIV; antiretroviral therapy; virologic failure; pediatrics; Africa
Mycobacterium tuberculosis is a common cause of bloodstream infections among HIV-infected adults in sub-Saharan Africa, and is associated with high morbidity and mortality. We found no cases of mycobacteremia among 93 ill, HIV-infected children in northern Tanzania, despite optimization of laboratory methods and selection of patients thought to be at highest risk for disseminated infection.
mycobacteremia; children; Africa; Tanzania; tuberculosis
HIV-infected individuals have poor responses to inactivated influenza vaccines. To evaluate the potential role of regulatory T (Treg) and B cells (Breg), we analyzed their correlation with humoral and cell-mediated immune (CMI) responses to pandemic influenza (pH1N1) monovalent vaccine in HIV-infected children and youth. Seventy-four HIV-infected, 4- to 25-y old participants in a 2-dose pH1N1 vaccine study had circulating and pH1N1-stimulated Treg and Breg measured by flow cytometry at baseline, post-dose 1 and post-dose 2. Concomitantly, CMI was measured by ELISPOT and flow cytometry; and antibodies by hemagglutination inhibition (HAI). At baseline, most of the participants had pH1N1-specific IFNγ ELISPOT responses, whose magnitude positively correlated with the baseline pH1N1, but not with seasonal H1N1 HAI titers. pH1N1-specific IFNγ ELISPOT responses did not change post-dose 1 and significantly decreased post-dose 2. In contrast, circulating CD4+CD25+% and CD4+FOXP3+% Treg increased after vaccination. The decrease in IFNγ ELISPOT results was marginally associated with higher pH1N1-specific CD19+FOXP3+ and CD4+TGFβ+% Breg and Treg, respectively. In contrast, increases in HAI titers post-dose 1 were associated with significantly higher circulating CD19+CD25+% post-dose 1, whereas increases in IFNγ ELISPOT results post-dose 1 were associated with higher circulating CD4+/C8+CD25+FOXP3+%. In conclusion, in HIV-infected children and youth, influenza-specific Treg and Breg may contribute to poor responses to vaccination. However, robust humoral and CMI responses to vaccination may result in increased circulating Treg and/or Breg, establishing a feed-back mechanism.
HIV infection; influenza vaccine; cell-mediated immunity; regulatory T cells; regulatory B cells
Yegor Voronin and colleagues explore how monoclonal antibodies against HIV could provide a new opportunity to further reduce mother-to-child transmission of HIV and propose that new interventions should consider issues related to implementation, feasibility, and access.
Please see later in the article for the Editors' Summary
Routine tuberculosis culture remains unavailable in many high-burden areas, including Tanzania. This study sought to determine the impact of providing mycobacterial culture results over standard of care [unconcentrated acid-fast (AFB) smears] on management of persons with suspected tuberculosis.
Adults and children with suspected tuberculosis were randomized to standard (direct AFB smear only) or intensified (concentrated AFB smear and tuberculosis culture) diagnostics and followed for 8 weeks. The primary endpoint was appropriate treatment (i.e. antituberculosis therapy for those with tuberculosis, no antituberculous therapy for those without tuberculosis).
Seventy participants were randomized to standard (n = 37, 53%) or intensive (n = 33, 47%) diagnostics. At 8 weeks, 100% (n = 22) of participants in follow up randomized to intensive diagnostics were receiving appropriate care, vs. 22 (88%) of 25 participants randomized to standard diagnostics (p = 0.14). Overall, 18 (26%) participants died; antituberculosis therapy was associated with lower mortality (9% who received antiuberculosis treatment died vs. 26% who did not, p = 0.04).
Under field conditions in a high burden setting, the impact of intensified diagnostics was blunted by high early mortality. Enhanced availability of rapid diagnostics must be linked to earlier access to care for outcomes to improve.
Mycobacterium tuberculosis; Diagnosis; Health resources; Sputum/microbiology; HIV; adult; Child
Mother to child transmission (MTCT) of HIV-1 remains an important problem in sub-Saharan Africa where most new pediatric HIV-1 infections occur. Early infant diagnosis of HIV-1 using dried blood spot (DBS) PCR among exposed infants provides an opportunity to assess current MTCT rates.
We conducted a retrospective data analysis on mother-infant pairs from all PMTCT programs in three regions of northern Tanzania to determine MTCT rates from 2008–2010. Records of 3,016 mother-infant pairs were assessed to determine early transmission among HIV-exposed infants in the first 75 days of life.
Of 2,266 evaluable infants in our cohort, 143 had a positive DBS PCR result at ≤75 days of life, for an overall transmission rate of 6.3%. Transmission decreased substantially over the period of study as more effective regimens became available. Transmission rates were tightly correlated to maternal regimen: 14.9% (9.5, 20.3) of infants became infected when women received no therapy; 8.8% (6.9, 10.7) and 3.6% (2.4, 4.8) became infected when women received single-dose nevirapine (sdNVP) or combination prophylaxis, respectively; the lowest MTCT rates occurred when women were on HAART, with 2.1% transmission (0.3, 3.9). Treatment regimens changed dramatically over the study period, with an increase in combination prophylaxis and a decrease in the use of sdNVP. Uptake of DBS PCR more than tripled over the period of study for the three regions surveyed.
Our study demonstrates significant reductions in MTCT of HIV-1 in three regions of Tanzania coincident with increased use of more effective PMTCT interventions. The changes we demonstrate for the period of 2008–2010 occurred prior to major changes in WHO PMTCT guidelines.
Background. The safety and immunogenicity of high-dose pandemic H1N1 (pH1N1) vaccination in perinatally human immunodeficiency virus type 1 (HIV-1)–infected children, adolescents, and young adults are unknown.
Methods. Two 30-μg doses of 2009 Novartis pH1N1 monovalent vaccine (Fluvirin) were administered 21–28 days apart to perinatally HIV-1–infected children, adolescents, and young adults. Antibodies were measured by hemagglutination inhibition (HAI) assay at baseline, 21–28 days after first vaccination, 7–13 days after the second vaccination, and 7 months after the first vaccination.
Results. Among the 155 participants, 54 were aged 4–8 years, 51 were aged 9–17 years, and 50 were aged 18–24 years. After 2 doses of Fluvirin, seroresponse (≥4-fold rise in HAI titers) was demonstrated in 79.6%, 84.8%, and 83% of participants in the aforementioned age groups, respectively, and seroprotection (HAI titers ≥40) was shown in 79.6%, 82.6%, and 85.1%, respectively. Of those lacking seroresponse (n = 43) or seroprotection (n = 37) after the first vaccination, 46.5% and 40.5% achieved seroresponse or seroprotection, respectively, after the second vaccination. Among participants who lacked seroprotection at entry, a “complete response” (both seroresponse and seroprotection) after first vaccination was associated with higher baseline log10 HAI titer and non-Hispanic ethnicity. No serious vaccine-related events occurred.
Conclusion. Two doses of double-strength pH1N1 vaccine are safe and immunogenic and may provide improved protection against influenza in perinatally HIV-1–infected children and youth.
Clinical Trials Registration. NCT00992836.
Gut microbial translocation (MT) is considered a major cause of immune activation (IA) and failure of immune reconstitution in HIV infection. This study investigated the relationship of virus replication, IA, CD4 counts and MT in HIV-infected children.
Lipopolysaccharide (LPS), bacterial 16S ribosomal DNA (16SrDNA) and soluble CD14 (sCD14) levels were determined in prospectively collected, stored plasma samples from PACTG 338, a 48 week study initiated in 1997 to compare efficacy of dual nucleosides with a ritonavir-containing regimen. Results of MT were correlated with study data for T cell IA, plasma virus load (VL) and CD4 counts in 85 HIV-infected children (ages 2-17 yrs) designated virologic responders (VR) or virologic failures (VF) at week 44 based on a cut-off of 400 HIV RNA copies/mL.
Levels of plasma LPS, 16SrDNA and sCD14 were increased in comparison to HIV-uninfected controls and did not decrease at week 44 even in VR patients. T cell IA was correlated with VL and sCD14 at entry and with 16SrDNA and sCD14 at week 44 in total patients and in the VF group. Changes in 16SrDNA correlated with changes in IA and negatively with changes in CD4 counts. 16SrDNA was correlated with sCD14 but not with LPS.
MT persists after 44 weeks of ART in VS and VF patients. In VF, 16SrDNA exhibited relationships to monocyte and T cell IA and CD4 counts but not with VL, suggesting a dominant role for MT in disease pathogenesis in HIV-infected children.
microbial translocation; immune activation; HIV infection; lipopolysaccharide; 16SrDNA
Future HIV vaccine efficacy trials with adolescents will need to ensure that participants comprehend study concepts in order to confer true informed assent. A Hepatitis B vaccine trial with adolescents offers valuable opportunity to test youth understanding of vaccine trial requirements in general.
Youth reviewed a simplified assent form with study investigators and then completed a comprehension questionnaire. Once enrolled, all youth were tested for HIV and confirmed to be HIV-negative.
123 youth completed the questionnaire (mean age=15 years; 63% male; 70% Hispanic). Overall, only 69 (56%) youth answered all six questions correctly.
Youth enrolled in a Hepatitis B vaccine trial demonstrated variable comprehension of the study design and various methodological concepts, such as treatment group masking.
CD8+ T-lymphocytes from HIV-1 infected individuals express unidentified factors that suppress viral replication by inhibiting HIV-1 gene expression. We examined the role of epigenetics in modulating the HIV-1 suppressive factors expressed by primary CD8+ T cells from subjects naturally controlling virus replication. HIV-1 suppression by CD8+ T-lymphocytes was reversed up to 40% by the addition of a histone deacetylase (HDAC) inhibitor. Noncytolytic suppression was not dependent on epigenetic changes within the target cells, as HDAC1 within the target cell was dispensable, and HIV-1 LTR histone acetylation remained unchanged in the presence of CD8+ T-lymphocytes. Histone deacetylation within CD8+ T-lymphocytes was necessary for potent HIV-1 suppression. Blocking HDACs impairs the ability of CD8+ T-lymphocytes to repress HIV-1 transcription, demonstrating that expression of a portion of the suppressive factors is regulated by epigenetics. These data provide a way to focus the search for the suppressive factors and to potentially modulate their expression.
Histone deacetylases; CD8+ T-lymphocyte HIV-1 suppression; Virus controllers
CD8+ T-lymphocytes can utilize noncytolytic mechanisms to suppress HIV-1 replication through the secretion of soluble factors. The secretion of MIP-1β, MIP-1α, IP-10, MIG, IL-1α, and interferon gamma correlated most strongly with soluble noncytolytic suppression (p < 0.0001). Since the noncytolytic response is impaired by histone hyperacetylation, we examined the ability of histone hyperacetylation to alter the expression of immune-related genes. MIP-1α and IP-10 were also among the genes that were down-regulated by histone hyperacetylation. We define a multifactorial cytokine profile of CD8+T lymphocytes capable of mediating noncytolytic suppression of CXCR4-tropic HIV-1 replication.
CD8+ T-lymphocyte; Noncytolytic Suppression; Cytokines; Chemokine; HIV-1
CD8-mediated virus inhibition can be detected in HIV-1-positive subjects who naturally control virus replication. Characterizing the inhibitory function of CD8+ T cells during acute HIV-1 infection (AHI) can elucidate the nature of the CD8+ responses that can be rapidly elicited and that contribute to virus control. We examined the timing and HIV-1 antigen specificity of antiviral CD8+ T cells during AHI. Autologous and heterologous CD8+ T cell antiviral functions were assessed longitudinally during AHI in five donors from the CHAVI 001 cohort using a CD8+ T cell-mediated virus inhibition assay (CD8 VIA) and transmitted/founder (T/F) viruses. Potent CD8+ antiviral responses against heterologous T/F viruses appeared during AHI at the first time point sampled in each of the 5 donors (Fiebig stages 1/2 to 5). Inhibition of an autologous T/F virus was durable to 48 weeks; however, inhibition of heterologous responses declined concurrent with the resolution of viremia. HIV-1 viruses from 6 months postinfection were more resistant to CD8+-mediated virus inhibition than cognate T/F viruses, demonstrating that the virus escapes early from CD8+ T cell-mediated inhibition of virus replication. CD8+ T cell antigen-specific subsets mediated inhibition of T/F virus replication via soluble components, and these soluble responses were stimulated by peptide pools that include epitopes that were shown to drive HIV-1 escape during AHI. These data provide insights into the mechanisms of CD8-mediated virus inhibition and suggest that functional analyses will be important for determining whether similar antigen-specific virus inhibition can be induced by T cell-directed vaccine strategies.
To describe the contribution of paediatric HIV and of HIV co-infections to admissions to a hospital in Moshi, Tanzania, using contemporary laboratory methods.
During 1 year, we enrolled consecutively admitted patients aged ≥2 months and <13 years with current or recent fever. All patients underwent standardized clinical history taking, a physical examination and HIV antibody testing; standard aerobic blood cultures and malaria film were also done, and hospital outcome was recorded. Early infant HIV diagnosis by HIV-1 RNA PCR was performed on those aged <18 months. HIV-infected patients also received serum cryptococcal antigen testing and had their CD4-positive T-lymphocyte count and percent determined.
A total of 467 patients were enrolled whose median age was 2 years (range 2 months–13 years); Of those patients, 57.2% were female and 12.2% were HIV-infected. Admission clinical diagnosis of HIV disease was made in 10.7% and of malaria in 60.4%. Of blood cultures, 5.8% grew pathogens; of these 25.9% were Salmonella enterica (including 6 Salmonella Typhi) and 22.2% Streptococcus pneumoniae. Plasmodium falciparum was identified on blood film of 1.3%. HIV infection was associated with S. pneumoniae (odds ratio 25.7, 95% CI 2.8, 234.0) bloodstream infection (BSI), but there was no evidence of an association with Escherichia coli or P. falciparum; Salmonella Typhi BSI occurred only among HIV-uninfected participants. The sensitivity and specificity of an admission clinical diagnosis of malaria were 100% and 40.3%; and for an admission diagnosis of bloodstream infection, they were 9.1% and 86.4%, respectively.
Streptococcus pneumoniae is a leading cause of bloodstream infection among paediatric admissions in Tanzania and is closely associated with HIV infection. Malaria was over-diagnosed clinically, whereas invasive bacterial disease was underestimated. HIV and HIV co-infections contribute to a substantial proportion of paediatric febrile admissions, underscoring the value of routine HIV testing.
Africa; bacteremia; HIV; paediatrics; Salmonella enterica; Streptococcus pneumoniae
HIV-infected youth are at risk of hepatitis B (HBV) infection and should be vaccinated. Previous reports suggest reduced response to standard HBV vaccine regimens.
HIV-infected youth, age 12 to <25 years, were randomly assigned to one of three treatment arms: Arm 1: Engerix B®, 20 mcg HBsAg; Arm 2: Engerix B®, 40 mcg; and Arm 3: Twinrix®, 20mcg HBsAg combined with 720 ELU hepatitis A antigen. Vaccines were administered at weeks 0, 4 and 24.
Characteristics of evaluable patients (n=336) at entry were similar in the study arms. At enrollment, median CD4+ T-cell count was 460 cells/mm3 (IQR: 305 to 668); 13% were < 200 cells/mm3. Among Engerix B®, 20 mcg recipients, 60.4% responded to vaccine (HBsAb ≥ 10 IU/mL at week 28). Improved vaccine response was seen in recipients of Engerix B®, 40 mcg, (73.2%, vs. Arm 1, p=0.04) and Twinrix® (75.4%, vs. Arm 1, p=0.02). In multivariate analysis, only baseline CD4+ T-cell count and study arm were independent predictors of vaccine response.
In HIV-infected youth, a three dose vaccination regimen with Engerix B®, 40 mcg, or Twinrix® and higher baseline CD4+ T-cell counts were independently associated with improved vaccine response.
HIV; Hepatitis B Vaccination; Adolescents; Engerix B; Twinrix
Therapeutic HIV vaccinations may alter the size of the resting memory CD4+ T-cell latent HIV reservoir as HIV establishes latency when memory responses are formed, including those toward HIV. Alternatively, latently infected CD4+ T cells maybe killed, while exiting the reservoir upon activation.
The effect of therapeutic immunization with modified vaccinia Ankara and Fowlpox-based HIV vaccines on the latent reservoir was examined in 19 young adults who were receiving effective antiretroviral therapy. Correlations between size of the reservoir [measured in infectious units per million (IUPM)] resting CD4+ T cells and HIV-specific immune responses, including immune activation were examined. Decay of the reservoir was assessed using random-effects model.
A modest transient decrease in the size of the reservoir was observed at week 40 [mean −0.31 log10 IUPM (95% confidence interval: −0.60 to −0.03; P =0.03] following HIV vaccinations. The estimated half-life (T1/2) of the reservoir during the 40 weeks following vaccination was 9.8 months and statistically different from zero (P =0.02), but 35.3 months and not different from zero (P =0.21) over 72 weeks of study. Latent reservoir size at baseline was not correlated with HIV-specific CD4+, CD8+ responses or immune activation, but became correlated with CD4+ IFNγ (r =0.54, P =0.02) and IL-2 responses at 6 weeks after immunization (r =0.48, P =0.04).
Therapeutic HIV vaccinations led to a transient increase in decay of latently infected CD4+ T cells. Further studies of therapeutic HIV vaccines may provide important insights into facilitating decay of the latent reservoir.
resting memory CD4+ T-cell latent reservoir; therapeutic HIV vaccines