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1.  Incident HSV-2 Infections Are Common Among HIV-1-discordant Couples 
The Journal of Infectious Diseases  2013;208(7):1093-1101.
Background. The synergy between herpes simplex virus type 2 (HSV-2) and human immunodeficiency virus type 1 (HIV-1) is well known, but lack of knowledge about the epidemiology of HSV-2 acquisition in HIV-1-discordant couples hampers development of HSV-2 prevention interventions that could reduce HIV-1 transmission.
Methods. HIV-1-discordant couples were enrolled in Nairobi, Kenya, and followed for up to 2 years. HSV-2 status was determined using HerpeSelect HSV-2 ELISA. Correlates of prevalence and incidence were assessed.
Results. Of 469 HIV-1-discordant couples, at baseline, 353 (75.3%) were affected by HSV-2, of which 189 (53.5%) were concordantly HSV-2 seropositive and 164 (46.5%) were HSV-2-discordant. Prevalence was lowest among HIV-1-uninfected men (39.9%) compared to HIV-1-infected women (64.8%), HIV-1-infected men (66.7%), and HIV-1-uninfected women (68.5%). During follow-up, HSV-2 seroincidence was 14.9 per 100 person-years. Incidence was 1.6-fold higher among females compared to males (95% confidence interval [CI], 1.00–2.48) and 2.5-fold higher in HIV-1-infected compared to uninfected women (95% CI, 1.12–5.74). At least 30% of incident HSV-2 infections originated from an outside partner.
Conclusions. The high HSV-2 prevalence and incidence in HIV-1-discordant couples in sub-Saharan Africa suggest HSV-2 treatment and prevention could be an effective targeted strategy to reduce HSV-2 and HIV-1 transmission in this high-risk population.
PMCID: PMC3762386  PMID: 23840044
HSV-2; herpes; HIV; discordant; serodiscordant; couples; genital ulcer disease; Kenya; incidence; prevalence; transmission; prevention; Africa; antiviral; seroconvert; ELISA
2.  Short Communication: T Cell Activation in HIV-1/Herpes Simplex Virus-2-Coinfected Kenyan Women Receiving Valacyclovir 
Herpes simplex virus-2 (HSV-2) suppression with acyclovir or valacyclovir reduces HIV-1 viral RNA levels; one hypothesis is that HSV-2 suppression reduces immune activation. We measured T cell immune activation markers among women participating in a randomized placebo-controlled trial of valacyclovir to reduce HIV-1 RNA levels among pregnant women. Although valacyclovir was associated with lower HIV-1 RNA levels, the distribution of both CD4+ and CD8+ CD38+HLA-DR+ T cells was not different among women taking valacyclovir when compared to women taking placebo. Further study is needed to understand the mechanism of HIV-1 RNA reduction following herpes suppression among those coinfected with HIV-1 and HSV-2.
PMCID: PMC3537320  PMID: 22852760
3.  Breast milk cellular HIV-specific interferon γ responses are associated with protection from peripartum HIV transmission 
AIDS (London, England)  2012;26(16):2007-2016.
Breast milk is a major route of infant HIV infection, yet the majority of breast-fed, HIV-exposed infants escape infection by unknown mechanisms. This study aimed to investigate the role of HIV-specific breast milk cells in preventing infant HIV infection.
A prospective study was designed to measure associations between maternal breast milk HIV-specific interferon-γ (IFN-γ) responses and infant HIV-1 detection at 1 month of age.
In a Kenyan cohort of HIV-infected mothers, blood and breastmilk HIV-gag IFN-γ ELISpot responses were measured. Logistic regression was used to measure associations between breast milk IFN-γ responses and infant HIV infection at 1 month of age.
IFN-γ responses were detected in breast milk from 117 of 170 (69%) women. IFN-γ responses were associated with breast milk viral load, levels of macrophage inflammatory protein (MIP) 1α, MIP-1β, regulated upon activation, normal T-cell expressed, and secreted and stromal-cell derived factor 1 and subclinical mastitis. Univariate factors associated with infant HIV infection at 1 month postpartum included both detection and breadth of breast milk IFN-γ response (P =0.08, P =0.04, respectively), breast milk MIP-1β detection (P =0.05), and plasma (P =0.004) and breast milk (P =0.004) viral load. In multivariate analyses adjusting for breast milk viral load and MIP-1β, breast milk IFN-γ responses were associated with an approximately 70% reduction in infant HIV infection [adjusted odds ratio (aOR) 0.29, 95% confidence interval (CI) 0.092–0.91], and each additional peptide pool targeted was associated with an approximately 35% reduction in infant HIV (aOR 0.65, 95% CI 0.44–0.97).
These data show breast milk HIV-gag-specific IFN-γ cellular immune responses are prevalent and may contribute to protection from early HIV transmission. More broadly, these data suggest breast milk cellular responses are potentially influential in decreasing mother-to-child transmission of viruses.
PMCID: PMC3718292  PMID: 22948269
breastfeeding; breast milk cytotoxic T lymphocytes; cytokines; early postnatal transmission; infant; MIP-1β; pediatric; sub-Saharan Africa
5.  C868T Single Nucleotide Polymorphism and HIV Type 1 Disease Progression Among Postpartum Women in Kenya 
The C868T single nucleotide polymorphism in the CD4 receptor encodes an amino acid substitution of tryptophan for arginine in the third domain. Previous studies suggest that C868T increases the risk of HIV-1 acquisition; however, the influence of this single nucleotide polymorphism (SNP) on disease progression has not been established. The presence of the C868T polymorphism was not statistically significantly associated with HIV-1 disease progression outcomes in a cohort of postpartum Kenyan women.
PMCID: PMC3358105  PMID: 21902583
6.  HIV-1-Specific Enzyme-Linked Immunosorbent Spot Assay Responses in HIV-1-Exposed Uninfected Partners in Discordant Relationships Compared to Those in Low-Risk Controls 
Clinical and Vaccine Immunology : CVI  2012;19(11):1798-1805.
A number of studies of highly exposed HIV-1-seronegative individuals (HESN) have found HIV-1-specific cellular responses. However, there is limited evidence that responses prevent infection or are linked to HIV-1 exposure. Peripheral blood mononuclear cells (PBMC) were isolated from HESN in HIV-1-discordant relationships and low-risk controls in Nairobi, Kenya. HIV-1-specific responses were detected using gamma interferon (IFN-γ) enzyme-linked immunosorbent spot (ELISpot) assays stimulated by peptide pools spanning the subtype A HIV-1 genome. The HIV-1 incidence in this HESN cohort was 1.5 per 100 person years. Positive ELISpot responses were found in 34 (10%) of 331 HESN and 14 (13%) of 107 low-risk controls (odds ratio [OR] = 0.76; P = 0.476). The median immunodominant response was 18.9 spot-forming units (SFU)/106 peripheral blood mononuclear cells (PBMC). Among HESN, increasing age (OR = 1.24 per 5 years; P = 0.026) and longer cohabitation with the HIV-1-infected partner (OR = 5.88 per 5 years; P = 0.003) were associated with responses. These factors were not associated with responses in controls. Other exposure indicators, including the partner's HIV-1 load (OR = 0.99 per log10 copy/ml; P = 0.974) and CD4 count (OR = 1.09 per 100 cells/μl; P = 0.238), were not associated with responses in HESN. HIV-1-specific cellular responses may be less relevant to resistance to infection among HESN who are using risk reduction strategies that decrease their direct viral exposure.
PMCID: PMC3491560  PMID: 22971780
7.  Acute Cytomegalovirus Infection Is Associated with Increased Frequencies of Activated and Apoptosis-Vulnerable T Cells in HIV-1-Infected Infants 
Journal of Virology  2012;86(20):11373-11379.
Cytomegalovirus (CMV) coinfection is associated with infant HIV-1 disease progression and mortality. In a cohort of Kenyan HIV-infected infants, the frequencies of activated (CD38+ HLA-DR+) and apoptosis-vulnerable (CD95+ Bcl-2−) CD4+ and CD8+ T cells increased substantially during acute CMV infection. The frequency of activated CD4+ T cells was strongly associated with both concurrent CMV coinfection (P = 0.001) and HIV-1 viral load (P = 0.05). The frequency of apoptosis-vulnerable cells was also associated with CMV coinfection in the CD4 (P = 0.02) and CD8 (P < 0.001) T cell subsets. Similar observations were made in HIV-exposed uninfected infants. CMV-induced increases in T cell activation and apoptosis may contribute to the rapid disease progression in coinfected infants.
PMCID: PMC3457128  PMID: 22875969
8.  Breast Milk HIV-1 RNA Levels and Female Sex Are Associated With HIV-1–Specific CD8+ T-Cell Responses in HIV-1–Exposed, Uninfected Infants in Kenya 
The Journal of Infectious Diseases  2011;204(11):1806-1810.
Background. Although evidence supports a relationship between human immunodeficiency virus (HIV)–1 exposure and HIV-1−specific CD8+ T cell responses, studies have not demonstrated a direct association between the quantity of HIV-1 to which a person is exposed and the presence or absence of a response.
Methods. From 1999 to 2005, maternal HIV-1 RNA levels were measured in blood, cervical secretions, and breast milk at delivery and 1 month after delivery. HIV-1−specific interferon (IFN)–γ Elispot assays were conducted to determine infant CD8+ T-cell responses at 3 months of age.
Results. Among 161 infants tested with Elispot assays, 23 (14%) had positive results. Mothers whose infants had a positive assay had higher breast milk HIV-1 RNA levels at month 1 compared with mothers whose infants had negative Elispot assays (3.1 vs 2.5 log10 copies/mL; P = .017). Female infants were also more likely to have positive Elispot assays than male infants (P = .046), and in multivariate analyses, both female sex and high breast milk HIV-1 levels remained important predictors of a positive response (P = .022 and P = .015, respectively).
Conclusions. Exposure to breast milk HIV-1 and sex were associated with development of HIV-1−specific CD8+ T-cell responses in infants. These data support a role for mucosal exposure via the oral route in induction of systemic HIV-1−specific cellular immunity.
PMCID: PMC3203234  PMID: 21984736
9.  Maternal Human Leukocyte Antigen - A*2301 Is Associated with Increased Mother-to-Child HIV-1 Transmission 
The Journal of infectious diseases  2010;202(8):1273-1277.
We examined associations between maternal HLA and vertical HIV-1 transmission in a perinatal cohort of 277 HIV-infected women in Nairobi. HLA class I genes were amplified using sequence-specific oligonucleotide probes and analyses were performed using logistic regression. Maternal A*2301 was associated with increased transmission risk before and after adjusting for maternal viral load (odds ratio [OR]=3.21; 95% CI: 1.42, 7.27, p=0.005, pcorr=0.04; adjusted OR=3.07; 95% CI: 1.26, 7.51, p=0.01, pcorr=NS). That maternal HLA-A*2301 was associated with transmission independent of plasma HIV-1 RNA levels, suggests that HLA may alter infectivity through mechanisms other than influencing HIV-1 viral load.
PMCID: PMC3404885  PMID: 20812845
Human immunodeficiency virus; vertical HIV-1 transmission; human leukocyte antigen
10.  Longitudinal Comparison of Chemokines in Breastmilk Early Postpartum Among HIV-1-Infected and Uninfected Kenyan Women 
Breastfeeding Medicine  2007;2(3):129-138.
Breastmilk chemokines have been associated with increased HIV-1 RNA levels in breastmilk and altered risk of mother-to-child HIV-1 transmission. To characterize CC and CXC chemokines in breastmilk postpartum, we collected breastmilk specimens at regular intervals for 6 months after delivery from women with and without HIV-1 infection and used commercial ELISA kits to measure breastmilk concentrations of MIP-1α, MIP-1β, RANTES, and SDF-1α. Among 54 HIV-1-infected and 26 uninfected women, mean chemokine levels were compared cross-sectionally and longitudinally at days 5 and 10, and months 1 and 3 postpartum. For both HIV-1-infected and uninfected women, breastmilk chemokine levels were highest at day 5 for MIP-1α, MIP-1β, and SDF-1α, and subsequently decreased. RANTES levels remained constant over the follow-up period among HIV-1-uninfected women, and increased moderately among HIV-1-infected women. For MIP-1β and RANTES, breastmilk levels were significantly higher among HIV-1-infected women compared to uninfected women early postpartum. In addition, HIV-1-infected women transmitting HIV-1 to their infant had consistently higher breastmilk RANTES levels than those who did not transmit, with the greatest difference observed at 1 month (2.68 vs. 2.21 log10 pg/mL, respectively; p = 0.007). In summary, all four chemokines were most elevated within the first month postpartum, a period of high transmission risk via breastmilk. MIP-1β and RANTES levels in breastmilk were higher among HIV-1-infected women than among uninfected women, and breastmilk RANTES was positively associated with vertical transmission in this study, consistent with results from our earlier cohort.
PMCID: PMC3381953  PMID: 17903098
11.  Consistency of Mycobacterium tuberculosis-Specific Interferon-Gamma Responses in HIV-1-Infected Women during Pregnancy and Postpartum 
Background. We determined the consistency of positive interferon-gamma (IFN-γ) release assays (IGRAs) to detect latent TB infection (LTBI) over one-year postpartum in HIV-1-infected women. Methods. Women with positive IGRAs during pregnancy had four 3-monthly postpartum IGRAs. Postpartum change in magnitude of IFN-γ response was determined using linear mixed models. Results. Among 18 women with positive pregnancy IGRA, 15 (83%) had a subsequent positive IGRA; 9 (50%) were always positive, 3 (17%) were always negative, and 6 (33%) fluctuated between positive and negative IGRAs. Women with pregnancy IGRA IFN-γ>8 spot forming cells (SFCs)/well were more likely to have consistent postpartum IGRA response (odds ratio: 10.0; 95% confidence interval (CI): 0.9–117.0). Change in IFN-γ response over postpartum was 10.2 SFCs/well (95% CI: −1.5–21.8 SFCs/well). Conclusion. Pregnancy positive IGRAs were often maintained postpartum with increased consistency in women with higher baseline responses. There were modest increases in magnitude of IGRA responses postpartum.
PMCID: PMC3312220  PMID: 22496602
12.  The impact of HIV-1 infection and exposure on natural killer (NK) cell phenotype in Kenyan infants during the first year of life 
Natural killer (NK) cells play an important role in the containment of HIV replication during primary infection, though their functions are impaired during chronic HIV infection. Infants experience more rapid HIV disease progression than adults, but contributions of infant NK cells to containing HIV infection are unknown. The aim of this study was to determine the impact of HIV infection on infant NK cell phenotype by evaluating samples and data from a cohort study of women and their infants, conducted in Nairobi, Kenya between 1999 and 2003. The percentage and phenotype of NK cells was evaluated longitudinally by multi-parameter flow cytometry over the first year of life in HIV-infected (HIV+, = 16), HIV-exposed uninfected (HIV-EU, n = 6), and healthy unexposed controls (HIV–, n = 4). At birth, NK subset distributions based on expression of CD56 and CD16 did not differ between HIV+, HIV-EU, or HIV– infants. However, HIV infection was associated with a subsequent decline in NK cells as a percentage of total lymphocytes (p < 0.001), and an expanding proportion of CD56-CD16+ NK cells (p < 0.001). Activated CD38brightCD69+ NK cells were more frequent in the HIV+ infants, followed by HIV-EU and HIV- infants, in both CD56dim (p = 0.005) and CD56bright compartments (p = 0.03). HIV infection and exposure was also associated with a significant decline in the percentage of perforin-expressing NK cells in the CD56dim compartment over the first year of life, with HIV+ infants losing approximately 2.5% (p < 0.001) and HIV-EU infants losing 3.0% (p = 0.01) of perforin+ cells per month. Thus, infant HIV infection is associated with alterations in NK cell subsets, activation, and cytolytic potential that could contribute to their poor control over HIV infection. Furthermore, exposure to HIV infection in infants who escaped infection is also associated with alterations in NK cells that may contribute to the reduced ability to fight infections that is observed in HIV-EU infants.
PMCID: PMC3533178  PMID: 23293640
NK cell; HIV-1; infancy; mother-to-child transmission; age; exposure; immune activation; cord blood
13.  CCR5, RANTES, and SDF-1 polymorphisms and mother-to-child HIV-1 transmission 
Among 288 HIV-1-infected, breastfeeding women who received zidovudine prophylaxis and were followed with their infants in Nairobi, we found no associations between maternal genetic polymorphisms in CCR5 (59029G/A, 59353T/C, 59356T/C, 59402G/A), RANTES (−403G/A), and SDF-1 (3′801G/A) and mother-to-child HIV-1 transmission; plasma, cervical, and breastmilk viral loads; or breastmilk chemokine concentrations.
PMCID: PMC2922909  PMID: 20518834
chemokines; CCR5; RANTES; SDF-1; HIV-1 transmission
14.  Phenotypic Characterization of HIV-Specific CD8+ T Cells during Early and Chronic Infant HIV-1 Infection 
PLoS ONE  2011;6(5):e20375.
Although CD8+ T cells play an important role in the containment of adult HIV-1 replication, their role in infant HIV-1 infection is not as well understood. Impaired HIV-specific CD8+ T cell responses may underlie the persistently high viral loads observed in infants. We examined the frequency and phenotype of infant HIV-specific CD8+ T cells in 7 HIV-infected antiretroviral therapy-naïve infants during the first 2 years of life, using class I HLA tetramers and IFN-γ-ELISPOT. The frequency (0.088–3.9% of CD3+CD8+ cells) and phenotype (CD27+CD28−, CD45RA+/−, CD57+/−, HLA-DR+, CD95+) of infant HIV-specific CD8+ T cells were similar to reports in adults undergoing early infection. Unlike adults, at 23–24 months post-infection a high frequency of HIV-specific CD8+ T cells expressed HLA-DR (mean 80%, range 68–85%) and CD95 (mean 88%, range 79–96%), suggesting sustained activation and vulnerability to apoptosis. Despite comparable expansion of HIV-specific CD8+ T cells of a similar phenotype to adults during early infection, infant T cells failed to contain HIV-1 replication, and remained persistently activated and vulnerable to apoptosis during chronic infection.
PMCID: PMC3105047  PMID: 21655252
15.  The challenge of assessing infant vaccine responses in resource-poor settings 
Expert review of vaccines  2010;9(6):665-674.
Newborns and infants are highly susceptible to infectious diseases, resulting in high mortality and morbidity, particularly in resource-poor settings. Many vaccines require several booster doses, resulting in an extensive vaccine schedule, and yet there is still inadequate protection from some of these diseases. This is partly due to the immaturity of the neonate and infant immune system. Little is known about the specific modifications to immunological assessment protocols in early life but increasing knowledge of infant immunology has helped provide better recommendations for assessing these responses. Since most new vaccines will eventually be deployed in low-income settings such as Africa, the logistics and resources of assessing immunity in such settings also need to be understood. In this article, we will review immunity to vaccines in early life, discuss the many challenges associated with assessing immunogenicity and provide practical tips.
PMCID: PMC2937226  PMID: 20518720
antibody; B cell; cord blood; developing country; immune response; infant; innate immunity; neonate; nonspecific effect; T cell; vaccine
16.  Acute cytomegalovirus infection in Kenyan HIV-infected infants 
AIDS (London, England)  2009;23(16):2173-2181.
Cytomegalovirus (CMV) coinfection may influence HIV-1 disease progression during infancy. Our aim was to describe the incidence of CMV infection and the kinetics of viral replication in Kenyan HIV-infected and HIV-exposed uninfected infants.
HIV-1 and CMV plasma viral loads were serially measured in 20 HIV-exposed uninfected and 44 HIV-infected infants born to HIV-infected mothers. HIV-infected children were studied for the first 2 years of life, and HIV-exposed uninfected infants were studied for 1 year.
CMV DNA was detected frequently during the first months of life; by 3 months of age, CMV DNA was detected in 90% of HIV-exposed uninfected infants and 93% of infants who had acquired HIV-1 in utero. CMV viral loads were highest in the 1–3 months following the first detection of virus and declined rapidly thereafter. CMV peak viral loads were significantly higher in the HIV-infected infants compared with the HIV-exposed uninfected infants (mean 3.2 versus 2.7 log10 CMV DNA copies/ml, respectively, P = 0.03). The detection of CMV DNA persisted to 7–9 months post-CMV infection in both the HIV-exposed uninfected (8/17, 47%) and HIV-infected (13/18, 72%, P = 0.2) children. Among HIV-infected children, CMV DNA was detected in three of the seven (43%) surviving infants tested between 19 and 21 months post-CMV infection. Finally, a strong correlation was found between peak CMV and HIV-1 viral loads (ρ = 0.40, P = 0.008).
Acute CMV coinfection is common in HIV-infected Kenyan infants. HIV-1 infection was associated with impaired containment of CMV replication.
PMCID: PMC2761509  PMID: 19617812
acute infection; cytomegalovirus; opportunistic infection; paediatric HIV; pathogenesis
19.  The detection of cytomegalovirus DNA in maternal plasma is associated with mortality in HIV-1 infected women and their infants 
AIDS (London, England)  2009;23(1):117-124.
Cytomegalovirus (CMV) is an important pathogen in healthy neonates and individuals with human immunodeficiency virus (HIV-1). The objective of this study was to determine whether the detection of CMV DNA (CMV DNAemia) in maternal plasma was associated with mortality in HIV-1 infected women or their infants.
A longitudinal study was designed to examine the relationship between maternal CMV DNAemia and maternal-infant mortality during two years postpartum. Sixty-four HIV-1 infected women and their infants were studied. CMV DNA loads were quantified in plasma from the mothers near the time of delivery. Baseline maternal CD4 counts, CD4%, HIV-1 RNA, and CMV DNAemia were evaluated as covariates of subsequent maternal or infant mortality in univariate and multivariate Cox regression.
CMV DNA was detected in 11/64 (17%) of the HIV-1 infected women. HIV-1 and CMV viral load were strongly correlated in CMV DNAemic women (ρ=0.84, p=0.001). Detection of CMV DNAemia was associated with decreased maternal survival at 24 months postpartum (log-rank p=0.006). Additionally, HIV-1 infected infants born to CMV DNAemic women had a 4-fold increased risk of mortality during 24 months of follow-up. Maternal CMV DNAemia remained a significant risk factor for mortality in HIV-1 infected infants after adjusting for maternal CD4 cells/mm3 (adjusted HR=4.3, CI=1.4–13), CD4% (HR=3.2, CI=1.0–10), HIV-1 viral load (HR=4.1, CI=1.4–12) or maternal death (HR=3.7, CI=1.0–13).
Maternal plasma CMV DNAemia identified a subgroup of Kenyan women and infants at high risk for death in the two years following delivery.
PMCID: PMC2739581  PMID: 19050393
cytomegalovirus; vertical transmission; viral load; infant mortality
20.  Albendazole treatment of HIV-1 and helminth co-infection: A randomized, double blind, placebo-controlled trial 
AIDS (London, England)  2008;22(13):1601-1609.
Several co-infections have been shown to impact the progression of HIV-1 infection. We sought to determine if treatment of helminth co-infection in HIV-1 infected adults impacted markers of HIV-1 disease progression.
To date there have been no randomized trials to examine the effects of soil-transmitted helminth eradication on markers of HIV-1 progression.
A randomized, double-blind, placebo-controlled trial of albendazole (400mg daily for three days) in antiretroviral-naïve HIV-1 infected adults (CD4 >200 cells/mm3) with soil-transmitted helminth infection was conducted at ten sites in Kenya (Clinical NCT00130910). CD4 and plasma HIV-1 RNA levels at 12 weeks following randomization were compared in the trial arms using linear regression, adjusting for baseline values.
Of 1,551 HIV-1 infected individuals screened for helminth-infection, 299 were helminth-infected. 234 adults were enrolled and underwent randomization and 208 individuals were included in intent-to-treat analyses. Mean CD4 count was 557 cells/mm3 and mean plasma viral load was 4.75 log10 copies/mL at enrolment. Albendazole therapy resulted in significantly higher CD4 counts among individuals with Ascaris lumbricoides infection after 12 weeks of follow up (+109 cells/mm3; 95% CI +38.9 to +179.0, p=0.003) and a trend for 0.54 log10 lower HIV-1 RNA levels (p=0.09). These effects were not seen with treatment of other species of soil-transmitted helminths.
Treatment of A. lumbricoides with albendazole in HIV-1 co-infected adults resulted in significantly increased CD4 counts during 3-month follow-up. Given the high prevalence of A. lumbricoides infection worldwide, deworming may be an important potential strategy to delay HIV-1 progression.
PMCID: PMC2637615  PMID: 18670219
HIV-1 progression; helminth; co-infection
21.  Maternal HLA Homozygosity and Mother-Child HLA Concordance Increase the Risk of Vertical Transmission of HIV-1 
The Journal of infectious diseases  2008;197(8):1156-1161.
Mother-child human leukocyte antigen (HLA) concordance and maternal HLA homozygosity may increase the risk of vertical transmission of human immunodeficiency virus type 1 (HIV-1) risk by reducing infant immune responses.
We analyzed mother-child HLA concordance and maternal HLA homozygosity in a Kenyan perinatal cohort receiving antenatal zidovudine. HLA concordance was scored as the number of shared class I alleles, and relative risk estimates were adjusted for maternal HIV-1 load.
Among 277 mother-infant pairs, HIV-1 transmission occurred in 58 infants (21%), with in utero transmission in 21 (36%), peripartum transmission in 26 (45%), and transmission via breast-feeding in 11 (19%). With increased concordance, we observed a significant increase in the risk of transmission overall (adjusted hazard ratio [aHR], 1.3 [95% confidence interval {CI}, 1.0–1.7]; P = .04), in utero (adjusted odds ratio, 1.72 [95% CI, 1.0 –1.7]; P = .04), and via breast-feeding (aHR, 1.6 [95% CI, 1.0 –2.5]; P = .04). Women with homozygosity had higher plasma HIV-1 RNA levels at 32 weeks of gestation (5.1 vs. 4.8 log10 copies/mL; P = .03) and an increased risk of transmission overall (aHR, 1.7 [95% CI, 1.1–2.7]; P = .03) and via breast-feeding (aHR, 5.8 [95% CI, 1.9 –17.7]; P = .002).
The risks of overall, in utero, and breast milk HIV-1 transmission increased with HLA concordance and homozygosity. The increased risk may be due to reduced alloimmunity or less diverse protective immune responses.
PMCID: PMC2689391  PMID: 18462163

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