Gender differences in perinatal HIV acquisition among African infants

Impact of early antiretroviral therapy, early life immunity and immune sex differences on HIV disease and posttreatment control in children

PURPOSE OF REVIEW

To review recent insights into the factors affecting HIV disease progression in children living with HIV, contrasting outcomes: following early ART initiation with those in natural, antiretroviral therapy (ART)-naive infection; in children versus adults; and in female individuals versus male individuals.

RECENT FINDINGS

Early life immune polarization and several factors associated with mother-to-child transmission of HIV result in an ineffective HIV-specific CD8+ T-cell response and rapid disease progression in most children living with HIV. However, the same factors result in low immune activation and antiviral efficacy mediated mainly through natural killer cell responses in children and are central features of posttreatment control. By contrast, rapid activation of the immune system and generation of a broad HIV-specific CD8+ T-cell response in adults, especially in the context of 'protective' HLA class I molecules, are associated with superior disease outcomes in ART-naive infection but not with posttreatment control. The higher levels of immune activation in female individuals versus male individuals from intrauterine life onwards increase HIV infection susceptibility in females in utero and may favour ART-naive disease outcomes rather than posttreatment control.

SUMMARY

Early-life immunity and factors associated with mother-to-child transmission typically result in rapid HIV disease progression in ART-naive infection but favour posttreatment control in children following early ART initiation.

The state of the pediatric HIV epidemic in Lesotho

OBJECTIVE

Lesotho does not have reliable data on HIV prevalence in children, relying on estimates generated from program data. The 2016 Lesotho Population-based HIV Impact Assessment (LePHIA) aimed to determine HIV prevalence among children 0-14 years to assess the effectiveness of the prevention of mother-to-child transmission (PMTCT) program and guide future policy.

METHODS

A nationally representative sample of children under 15 years underwent household-based, two-stage HIV testing from November 2016-May 2017. Children <18 months with a reactive screening test were tested for HIV infection using total nucleic acid (TNA) PCR. Parents (61.1%) or legal guardians (38.9%) provided information on children's clinical history. Children aged 10-14 years also answered a questionnaire on knowledge and behaviors.

RESULTS

HIV prevalence was 2.1% [95% confidence interval (CI): 1.5-2.6]. Prevalence in 10-14 year olds (3.2%; 95% CI: 2.1, 4.2) was significantly greater compared to 0-4 year olds (1.0%; 95% CI: 0.5, 1.6). HIV prevalence in girls and boys was 2.6% (95% CI: 1.8-3.3) and 1.5% (95% CI: 1.0-2.1), respectively. Based on reported status and/or the presence of detectable antiretrovirals, 81.1% (95% CI: 71.7-90.4) of HIV-positive children were aware of their status, 98.2% (95% CI: 90.7-100.0) of those aware were on antiretroviral therapy (ART) and 73.9% (95% CI: 62.1-85.8) of those on ART were virally suppressed.

CONCLUSIONS

Despite the roll-out of Option B+ in Lesotho in 2013, pediatric HIV prevalence remains high. Further research is required to understand the greater prevalence among girls, barriers to PMTCT, and how to better achieve viral suppression in children with HIV.

Sex Differences in HIV Infection

Biological sex has wide-ranging impacts on HIV infection spanning differences in acquisition risk, the pathogenesis of untreated infection, impact of chronic treated disease and prospects for HIV eradication or functional cure. This chapter summarizes the scope of these differences and discusses several features of the immune response thought to contribute to the clinical outcomes.

Vertical HIV transmission within 18 months post partum among women on lifelong antiretroviral therapy for HIV in Dar es Salaam, Tanzania: a prospective cohort study

BACKGROUND

The UNAIDS estimate of vertical HIV transmission in Tanzania is high (11%), despite 84% uptake of antiretroviral therapy (ART) among pregnant women with HIV. We aimed to evaluate vertical transmission and its determinants by 18 months post partum among women on lifelong ART in routine health-care settings in Tanzania.

METHODS

We conducted a prospective cohort study in 226 health facitilies across Dar-es-Salaam, Tanzania. Eligible participants were pregnant women of any age with HIV, and later their infants, who enrolled in routine health-care services for the prevention of vertical transmission. We prospectively followed up mother-infant pairs at routine monthly visits until 18 months post partum and extracted data from the care and treatment clinic (CTC2) database, a national electronic database that stores patient-level HIV care and treatment clinic data. The primary outcome was time from birth to HIV diagnosis, defined as a positive infant HIV DNA PCR or antibody test from age 18 months. We used the Kaplan-Meier method to estimate cumulative risk of vertical transmission by 18 months post partum and Cox proportional hazards regression with shared frailties to account for potential clustering in health facilities to evaluate predictors of transmission.

FINDINGS

Between Jan 1, 2015, and Dec 31, 2017, 22 930 pregnant women with HIV (median age 30 years, IQR 25-34) enrolled on a care programme. After excluding 9140 (39·9%) women and 539 (2·4%) infants with missing outcome data, 13 251 (59·0%) mother-infant pairs were analysed, of whom 6072 (45·8%) women were already on ART before pregnancy. By 18 months post partum, 159 (1·2%) of 13 251 infants were diagnosed with HIV, equivalent to a risk of vertical transmission of 1·4% (95% CI 1·2-1·6). In the complete case analysis, the rates of vertical transmission were higher among women who enrolled in the third trimester of pregnancy than among those who enrolled in the first trimester (adjusted hazard ratio 3·01, 95% CI 1·59-5·70; p=0·0003), among women with advanced HIV disease than among those with early-stage disease (1·89, 1·22-2·93; p=0·0046), and among women who were on a second-line ART regimen than among those on a first-line regimen (3·58, 1·08-11·82; p=0·037). By contrast, the rate of vertical transmission was lower among women who were already on ART at enrolment than among those starting ART at enrolment (0·39, 0·25-0·60; p<0·0001) as well as among women in high-volume clinics than among those in low-volume clinics (0·46 (0·24-0·90; p<0·0097).

INTERPRETATION

Provision of ART for life (WHO's option B+ recommendation) has reduced the risk of vertical transmission to less than 2% among pregnant women with HIV in routine care settings in urban Tanzania. There is still a need to improve timely HIV diagnosis and ART uptake, and to optimise follow-up for the prevention of vertical transmission and the uptake of infant HIV testing.

FUNDING

Swedish International Development Cooperation Agency.

Role of Early Life Cytotoxic T Lymphocyte and Natural Killer Cell Immunity in Paediatric HIV Cure/Remission in the Anti-Retroviral Therapy Era

Only three well-characterised cases of functional cure have been described in paediatric HIV infection over the past decade. This underlines the fact that early initiation of combination antiretroviral therapy (cART), whilst minimising the size of the viral reservoir, is insufficient to achieve cure, unless other factors contribute. In this review, we consider these additional factors that may facilitate functional cure in paediatric infection. Among the early life immune activity, these include HIV-specific cytotoxic T-lymphocyte (CTL) and natural killer (NK) cell responses. The former have less potent antiviral efficacy in paediatric compared with adult infection, and indeed, in early life, NK responses have greater impact in suppressing viral replication than CTL. This fact may contribute to a greater potential for functional cure to be achieved in paediatric versus adult infection, since post-treatment control in adults is associated less with highly potent CTL activity, and more with effective antiviral NK cell responses. Nonetheless, antiviral CTL responses can play an increasingly effective role through childhood, especially in individuals expressing then 'protective' HLA-I molecules HLA-B*27/57/58:01/8101. The role of the innate system on preventing infection, in shaping the particular viruses transmitted, and influencing outcome is discussed. The susceptibility of female fetuses to in utero mother-to-child transmission, especially in the setting of recent maternal infection, is a curiosity that also provides clues to mechanisms by which cure may be achieved, since initial findings are that viral rebound is less frequent among males who interrupt cART. The potential of broadly neutralising antibody therapy to facilitate cure in children who have received early cART is discussed. Finally, we draw attention to the impact of the changing face of the paediatric HIV epidemic on cure potential. The effect of cART is not limited to preventing AIDS and reducing the risk of transmission. cART also affects which mothers transmit. No longer are mothers who transmit those who carry genes associated with poor immune control of HIV. In the cART era, a high proportion (>70% in our South African study) of transmitting mothers are those who seroconvert in pregnancy or who for social reasons are diagnosed late in pregnancy. As a result, now, genes associated with poor immune control of HIV are not enriched in mothers who transmit HIV to their child. These changes will likely influence the effectiveness of HLA-associated immune responses and therefore cure potential among children.

Understanding Viral and Immune Interplay During Vertical Transmission of HIV: Implications for Cure

Despite the significant progress that has been made to eliminate vertical HIV infection, more than 150,000 children were infected with HIV in 2019, emphasizing the continued need for sustainable HIV treatment strategies and ideally a cure for children. Mother-to-child-transmission (MTCT) remains the most important route of pediatric HIV acquisition and, in absence of prevention measures, transmission rates range from 15% to 45% via three distinct routes: in utero, intrapartum, and in the postnatal period through breastfeeding. The exact mechanisms and biological basis of these different routes of transmission are not yet fully understood. Some infants escape infection despite significant virus exposure, while others do not, suggesting possible maternal or fetal immune protective factors including the presence of HIV-specific antibodies. Here we summarize the unique aspects of HIV MTCT including the immunopathogenesis of the different routes of transmission, and how transmission in the antenatal or postnatal periods may affect early life immune responses and HIV persistence. A more refined understanding of the complex interaction between viral, maternal, and fetal/infant factors may enhance the pursuit of strategies to achieve an HIV cure for pediatric populations.

Low Pretreatment Viral Loads in Infants With HIV in an Era of High-maternal Antiretroviral Therapy Coverage

BACKGROUND

With expansion of antiretroviral therapy (ART) programs, transmission rates are low but new infant infections still occur. We investigated predictors of pre-ART viral load (VL) and CD4+ T-cell counts and percentages in infants diagnosed with HIV at birth in a setting with high coverage of maternal ART and infant prophylaxis.

METHODS

As part of an early treatment study, 97 infants with confirmed HIV-infection were identified at a hospital in Johannesburg, South Africa. Infant VL and CD4+ T-cell parameters were measured before ART initiation. Data were collected on maternal characteristics, including VL, CD4+ T-cell counts and ART, and infant characteristics, including sex, birth weight, and mode of delivery.

RESULTS

Pre-ART, median infant VL was 28,405 copies/mL [interquartile range (IQR): 2515-218,150], CD4+ T-cell count 1914 cells/mm (IQR: 1474-2639) and percentage 40.8% (IQR: 32.2-51.2). Most (80.4%) infants were born to mothers who received ART during pregnancy and 97.9% of infants received daily nevirapine prophylaxis until ART initiation at median of 2 days of age (IQR: 1-7). Infant pre-ART VL was more likely to be ≥1000 copies/mL when their mothers had VL ≥1000 copies/mL [Odds Ratio (OR): 6.88, 95% confidence interval (CI): 2.32-20.41] and was higher in boys than girls (OR: 3.29, 95% CI: 1.07-9.95). Lower maternal CD4+ T-cell count (<350 cells/mm) was associated with lower infant CD4+ T-cell count (<1500 cells/mm) (OR: 3.59, 95% CI: 1.24-10.43).

CONCLUSIONS

Pre-ART VL and CD4+ T-cell parameters of intrauterine-infected infants were associated with VL and CD4+ T-cell counts of their mothers. Maternal ART during pregnancy may begin treatment of intrauterine infection and may mask the severity of disease in infected infants identified in the current era with high-maternal ART coverage.

Infant HIV diagnosis and turn-around time for testing in Malawi, 2015

Background

For HIV-exposed infants in Malawi, there are missed opportunities at each step of the testing and treatment cascade.

Objective

This study assessed factors associated with HIV positivity among infants in Malawi and turn-around times for infant HIV testing.

Methods

HIV testing data for infants aged 0–18 months from 2012 to 2015 were extracted from the Malawi HIV laboratory information management system and analysed using logistic regression. Turn-around time was defined as time between collection of samples to results dispatch from the laboratory.

Results

A total of 106 997 tests were included in the analyses. A subset of 76 006 observations with complete dates were included in the turn-around time analysis. Overall positivity was 4.2%. Factors associated with positivity were increasing age (infants aged 3–6 months: adjusted odds ratio [aOR] = 2.24; infants aged 6–9 months: aOR = 3.42; infants aged > 9 months: aOR = 4.24), female sex (aOR = 1.08) and whether the mother was alive and not on antiretroviral therapy at time of the infant’s test (aOR = 1.57). Provision of HIV prophylaxis to the infant after birth (aOR = 0.38) was found to be protective against HIV positivity. The median turn-around time was 24 days (increased from 19 to 34 days between 2012 and 2015).

Conclusion

Infant HIV positivity has decreased in Malawi, whereas turn-around time has increased. Factors associated with positivity include increasing age, female sex, and whether the mother was alive and not on antiretroviral therapy at the time of the infant’s test.

Implementation of blanket provider-initiated testing and counselling: Predictors of HIV seropositivity among infants, children and adolescents in Cameroon

Objectives

Study design

Methods

Results

Conclusions

•

Methods to increase the yield of PITC remain unclear.

•

HIV seropositivity predictors could improve PITC yield.

•

Identifying HIV seropositivity predictors among children and adolescents.

•

Targeted HIV testing to improve PITC yield in HIV high burden countries.

•

HIV seropositivity predictors could reduce gap in pediatric and adolescent ART.

Sex-specific innate immune selection of HIV-1 in utero is associated with increased female susceptibility to infection

Female children and adults typically generate more efficacious immune responses to vaccines and infections than age-matched males, but also suffer greater immunopathology and autoimmune disease. We here describe, in a cohort of > 170 in utero HIV-infected infants from KwaZulu-Natal, South Africa, fetal immune sex differences resulting in a 1.5–2-fold increased female susceptibility to intrauterine HIV infection. Viruses transmitted to females have lower replicative capacity (p = 0.0005) and are more type I interferon-resistant (p = 0.007) than those transmitted to males. Cord blood cells from females of HIV-uninfected sex-discordant twins are more activated (p = 0.01) and more susceptible to HIV infection in vitro (p = 0.03). Sex differences in outcome include superior maintenance of aviraemia among males (p = 0.007) that is not explained by differential antiretroviral therapy adherence. These data demonstrate sex-specific innate immune selection of HIV associated with increased female susceptibility to in utero infection and enhanced functional cure potential among infected males.

Sex differences in the immune response to vaccines and infections have been well described in children and adults. Here the authors describe, in a cohort of 177 HIV-infected infants, innate immune sex differences in fetal life that increase female susceptibility to intrauterine HIV infection and increase the chances of subsequent HIV remission in infected males.

Prevalence and determinants of HIV shedding in breast milk during continued breastfeeding among Zambian mothers not on antiretroviral treatment (ART): A cross-sectional study

The risk of postnatal HIV transmission exists throughout the breastfeeding period. HIV shedding in breast milk beyond six months has not been studied extensively. The aim of this study was to determine prevalence and determinants of HIV shedding in breast milk during continued breastfeedingA cross-sectional study was nested in the PROMISE-PEP trial in Lusaka, Zambia to analyze breast milk samples collected from both breasts at week 38 post-partum (mid-way during continued breastfeeding). We measured concurrent HIV deoxyribonucleic acid (DNA) and HIV ribonucleic acid (RNA) as proxies for cell-associated HIV (CAV) and cell-free HIV (CFV) shedding in breast milk respectively. Participants' socio-demographic date, concurrent blood test results, sub clinical mastitis test results and contraceptive use data were available. Logistic regression models were used to identify determinants of HIV shedding in breast milk (detecting either CAV or CFV).The prevalence of HIV shedding in breast milk at 9 months post-partum was 79.4% (95%CI: 74.0 - 84.0). CAV only, CFV only and both CAV and CFV were detectable in 13.7%, 17.3% and 48.4% mothers, respectively. The odds of shedding HIV in breast milk decreased significantly with current use of combined oral contraceptives (AOR: 0.37; 95%CI: 0.17 - 0.83) and increased significantly with low CD4 count (AOR: 3.47; 95%CI: 1.23 - 9.80), unsuppressed plasma viral load (AOR: 6.27; 95%CI: 2.47 - 15.96) and severe sub-clinical mastitis (AOR: 12.56; 95%CI: 2.48 - 63.58).This study estimated that about 80% of HIV infected mothers not on ART shed HIV in breast milk during continued breastfeeding. Major factors driving this shedding were low CD4 count, unsuppressed plasma viral load and severe sub-clinical mastitis. The inverse relationship between breast milk HIV and use of combined oral contraceptives needs further clarification. Continued shedding of CAV may contribute to residual postnatal transmission of HIV in mothers on successful ART.

Neurodevelopment at 11 months after starting antiretroviral therapy within 3 weeks of life

BACKGROUND

Antiretroviral therapy (ART) started between 7 and 12 weeks of age improves neurodevelopmental outcomes in HIV-infected (HIV+) infants, but the impact of even earlier initiation is not yet described.

OBJECTIVES

We assessed the early neurodevelopment of HIV+ infants who started ART within 21 days of life.

METHOD

Participants were enrolled from the public sector birth HIV-diagnosis programme. Inclusion criteria included the following: birth weight > 2000 g, infant commencing ART < 6 weeks and no infant cytomegalovirus disease. Antiretroviral therapy included Zidovudine/Lamivudine/Nevirapine for the first 2 weeks, the latter then replaced by Lopinavir/Ritonavir. Once body weight > 3 kg and gestational age > 44 weeks, Abacavir replaced Zidovudine. The Griffiths mental development scales (GMDS) were administered at 10-12 months.

RESULTS

Of 29 infants assessed, 23 (79%) were girls. Mean birth weight was 3002 ± 501 g. Twenty-four mothers (83%) received ART during pregnancy. Seven (24%) infants were diagnosed HIV+ within 48 h of birth. Median [interquartile range] viral load (VL) at diagnosis was 3904 [259-16 922] copies/mL, age starting ART was 6.0 [3-10] days and age at VL suppression was 19.1 [15-36] weeks. At the GMDS assessment, nine (31%) participants had detectable VL and 26 (90%) had World Health Organization (WHO) clinical stage I disease. The GMDS was performed at a mean age of 11.5 ± 0.8 months. Mean quotients were within the average range: Global Griffiths score was 103.6 ± 10.9 and mean quotients on the subscales ranged from lowest 95.9 ± 13.4 for locomotor to highest 112.8 ± 11.3 for hearing-and-language.

CONCLUSION

Preliminary findings in this small group suggest that early neurodevelopmental scores are within the normal range in infants with perinatal HIV infection who started ART at a median of 6 days.

Adolescent HIV treatment in South Africa's national HIV programme: a retrospective cohort study

BACKGROUND

The number of South African adolescents receiving HIV care and treatment in South Africa is growing. By use of routinely collected laboratory data from South Africa's National HIV Programme, we aimed to quantify the numbers of adolescents accessing HIV care and treatment over time, characterise the role of perinatal infection in these trends, and estimate proportions of adolescents seeking HIV care and antiretroviral therapy (ART) in South Africa's public sector.

METHODS

We did a retrospective, descriptive cohort study of children and adolescents aged 1-19 years accessing care in South Africa's public sector HIV treatment programme from 2005 to 2016 with a CD4 cell count or viral load recorded in South Africa's National Health Laboratory Service database. We estimated the total number of children and adolescents entering HIV care with a CD4 cell count or viral load test result by calendar period, as well as the proportion in care and receiving ART with at least one viral load test result. We stratified analyses by gender and by whether the patient entered care at younger than 15 years (probably perinatally infected) or at 15-19 years (probably infected in adolescence).

FINDINGS

We identified 730 882 patients aged 1-19 years at entry to care between Jan 1, 2005, and Dec 31, 2016. 209 205 (54%) of 388 439 patients entering care younger than 15 years and 301 242 (88%) of 342 443 patients entering care aged 15-19 were female. During the study period, the number of virologically monitored patients aged 15-19 years receiving ART increased from 7949 in 2005-08 to 80 918 in 2013-16. 92 783 (66%) of 140 028 patients aged 15-19 years seeking care started ART by 2016, well below UNAID's target of ART for 90% of those diagnosed. We project that the number of adolescents on ART will continue to rise.

INTERPRETATION

The many adolescents aged 15-19 years receiving ART reflect the ageing of children entering care at ages 1-14 years, and increases in care-seeking among horizontally infected adolescents aged 15-19 years. However, many adolescents seeking care do not start ART, suggesting an urgent need for interventions to increase uptake of ART and improve services for this population.

FUNDING

US National Institutes of Health, and the President's Emergency Plan for AIDS Relief through the US Agency for International Development.

Maternal age, infant age, feeding options, single/multiple pregnancy, type of twin sets and mother-to-child transmission of HIV

BACKGROUND

Some risk factors for mother-to-child transmission (MTCT) of HIV have been identified. To further reduce MTCT, other risk factors were evaluated.

MATERIALS AND METHODS

A retrospective study on early infant diagnosis was conducted. Two-sided chi-square test was used to assess associations with infant HIV status.

RESULTS

A total of 15 233 HIV-infected mothers and 15 404 infants were recruited. MTCT rate was 9.34%. Only 3.8% of infants born to mothers on antiretroviral treatment were infected. Under nevirapine, 4.1% of infants were infected. MTCT increased with infant' age at testing. Younger mothers tend to transmit more HIV (P = 0.003). More children were infected in single pregnancies compared with multiple pregnancies, P < 0.001. There were more infections in male-female twins' sets (P = 0.037).

CONCLUSIONS

Maternal age, type of pregnancy and twins' sets are new MTCT risk factors. Strategies to further decrease transmission through family planning, pre/post natal consultations and clinical practices are needed.

Strong sex bias in elite control of paediatric HIV infection

Background:

Reports of posttreatment control following antiretroviral therapy (ART) have prompted the question of how common immune control of HIV infection is in the absence of ART. In contrast to adult infection, where elite controllers have been very well characterized and constitute approximately 0.5% of infections, very few data exist to address this question in paediatric infection.

Methods:

We describe 11 ART-naive elite controllers from 10 cohorts of HIV-infected children being followed in South Africa, Brazil, Thailand, and Europe.

Results:

All but one of the elite controllers (91%) are females. The median age at which control of viraemia was achieved was 6.5 years. Five of these 11 (46%) children lost control of viraemia at a median age of 12.9 years. Children who maintained control of viraemia had significantly higher absolute CD4⁺ cell counts in the period of elite control than those who lost viraemic control. On the basis of data available from these cohorts, the prevalence of elite controllers in paediatric infection is estimated to be 5–10-fold lower than in adults.

Conclusion:

Although conclusions are limited by the study design, these data suggest that, whilst paediatric elite control can be achieved, compared with adult elite controllers, this occurs rarely, and takes some years after infection to achieve. Also, loss of immune control arises in a high proportion of children and often relatively rapidly. These findings are consistent with the more potent antiviral immune responses observed in adults and in females.

Pregnancy outcomes in perinatally HIV-infected young women in Madrid, Spain: 2000-2015

Background

An increasing number of perinatally HIV-infected women (PHIV) are reaching adulthood and becoming pregnant. Most PHIV women have been exposed to a high number of antiretroviral regimens, and they may have difficulties to achieve viral suppression. Psychosocial problems are not uncommon and could be an important barrier for treatment adherence. The effects of chronic HIV infection and long-term exposure to antiretroviral treatment of PHIV women cause concerns on the developing fetus. The aims of this study were to describe the prevention of mother-to-child transmission strategies in PHIV women and the infant outcomes in the Madrid Cohort of HIV-infected mother-infant pairs.

Methods

All PHIV pregnant women registered in the Cohort that gave birth from 2000 to 2015 were included in the study.

Results

Twenty-eight pregnancies in twenty-two perinatally infected women were registered. Most women were Caucasian and heavily treatment-experienced. Nine cases (32.1%) were at high risk of HIV mother-to-child transmission. Maternal HIV-1 viral load was detectable close to delivery in four women (14.3%). The management of these cases was described, and the treatment strategies were discussed. None of the newborns acquired HIV infection. Eight infants (28.6%) were small for gestational age.

Conclusions

This study included a large series of pregnancies among PHIV women attended according to a youth-centered care model. The challenges in the management of this population by health-care providers were described. Specific strategies to minimize perinatal transmission risks should be addressed in future collaborative studies.

Sex Differences in Antiretroviral Therapy Initiation in Pediatric HIV Infection

The incidence and severity of infections in childhood is typically greater in males. The basis for these observed sex differences is not well understood, and potentially may facilitate novel approaches to reducing disease from a range of conditions. We here investigated sex differences in HIV-infected children in relation to antiretroviral therapy (ART) initiation and post-treatment outcome. In a South African cohort of 2,101 HIV-infected children, we observed that absolute CD4+ count and CD4% were significantly higher in ART-naïve female, compared to age-matched male, HIV-infected children. Absolute CD4 count and CD4% were also significantly higher in HIV-uninfected female versus male neonates. We next showed that significantly more male than female children were initiated on ART (47% female); and children not meeting criteria to start ART by >5 yrs were more frequently female (59%; p<0.001). Among ART-treated children, immune reconstitution of CD4 T-cells was more rapid and more complete in female children, even after adjustment for pre-ART absolute CD4 count or CD4% (p=0.011, p=0.030, respectively). However, while ART was initiated as a result of meeting CD4 criteria less often in females (45%), ART initiation as a result of clinical disease in children whose CD4 counts were above treatment thresholds occurred more often in females (57%, p<0.001). The main sex difference in morbidity observed in children initiating ART above CD4 thresholds, above that of TB disease, was as a result of wasting and stunting observed in females with above-threshold CD4 counts (p=0.002). These findings suggest the possibility that optimal treatment of HIV-infected children might incorporate differential CD4 treatment thresholds for ART initiation according to sex.

Gender-sensitive reporting in medical research

Sex and gender differences influence the health and wellbeing of men and women. Although studies have drawn attention to observed differences between women and men across diseases, remarkably little research has been pursued to systematically investigate these underlying sex differences. Women continue to be underrepresented in clinical trials, and even in studies in which both men and women participate, systematic analysis of data to identify potential sex-based differences is lacking. Standards for reporting of clinical trials have been established to ensure provision of complete, transparent and critical information. An important step in addressing the gender imbalance would be inclusion of a gender perspective in the next Consolidated Standards of Reporting Trials (CONSORT) guideline revision. Uniform Requirements for Manuscripts Submitted to Biomedical Journals, as a set of well-recognized and widely used guidelines for authors and biomedical journals, should similarly emphasize the ethical obligation of authors to present data analyzed by gender as a matter of routine. Journal editors are also promoters of ethical research and adequate standards of reporting, and requirements for inclusion of gender analyses should be integrated into editorial policies as a matter of urgency.

Host factors that influence mother-to-child transmission of HIV-1: genetics, coinfections, behavior and nutrition

Mother-to-child transmission (MTCT) is the most important mode of HIV-1 acquisition among infants and children and it can occur in utero, intrapartum and postnatally through breastfeeding. Great progress has been made in preventing MTCT through use of antiretroviral regimens during gestation, labor/delivery and breastfeeding. The mechanisms of MTCT, however, are multifactorial and remain incompletely understood. This review focuses on select host factors affecting MTCT, in particular genetic factors, coexisting infections, behavioral factors and nutrition. Whereas much emphasis has been placed on decreasing maternal HIV-1 viral load, an important determinant of MTCT, through use of antiretroviral agents, complementary focus on overall maternal health is often neglected. By addressing coinfections in mothers and infants, improving the mother's nutritional status and modifying risky behaviors and practices, not only is maternal and child health improved, but a direct benefit in reducing MTCT can be derived. The study of genetic variations in susceptibility to HIV-1 infection is rapidly evolving, and the future is likely to bring revolutionary changes in HIV-1 prevention by enhancing natural resistance to infection and by individually tailoring pharmacologic regimens.

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

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 log(10) 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.

Extended antenatal use of triple antiretroviral therapy for prevention of mother-to-child transmission of HIV-1 correlates with favorable pregnancy outcomes

OBJECTIVE

To evaluate pregnancy outcomes in a cohort of HIV-infected women receiving triple antiretroviral therapy (ART) for prevention of mother-to-child-transmission.

METHODS

A retrospective cohort study with review of records of 3273 HIV-positive women receiving prenatal care in Malawi and Mozambique from July 2005 to December 2009 was conducted in Drug Resource Enhancement Against AIDS and Malnutrition (DREAM) centers. Patients were offered nevirapine-based triple ART initiated in pregnancy until 6 months postpartum. Main outcome measures were maternal mortality, abortion/stillbirth, prematurity, and low birth weight.

RESULTS

Maternal mortality was 1.2% (42/3273): 7.4% in 68 women with no antenatal ART and 0.7% in 1370 with at least 90 days of antenatal ART [P < 0.001; odds ratio (OR) 0.29 (95% confidence interval [CI] 0.14-0.96]. Abortion/stillbirth was 5.2% (169/3273): 26.5% in 68 women with no ART and 5.0% in 1370 women with at least 90 days of antenatal ART [P < 0.001; OR 0.39 (95% CI 0.27-0.57)]. Prematurity was 19.1%: 70% in 10 women with no antenatal ART and 8.5% in 1330 women with at least 90 days of antenatal ART [P < 0.001; OR 0.15 (95% CI 0.14-0.19)]. Low birth weight was 11.5% (57/496) and not associated with ART duration. The protective effect of antenatal ART against mortality, fetal demise, and prematurity was independent of CD4 strata. Multivariate analysis for BMI, CD4 cell count, virus load, days in care, predelivery length of ART, and hemoglobin demonstrated an independent association between predelivery length of ART and CD4 with maternal mortality, abortion/stillbirth, and prematurity. ART toxicities were infrequent (5.2%).

CONCLUSION

Antenatal triple ART reduces adverse pregnancy outcomes in HIV-infected women.

Prevalence and clinical pattern of paediatric HIV infection at the University College Hospital, Ibadan, Nigeria: a prospective cross-sectional study

BACKGROUND

The prevalence of Paediatric HIV infection is largely unknown in many countries in sub-Saharan Africa. This study was aimed at determining the prevalence, clinical pattern of HIV infection and outcome among new patients aged <15 years using age-specific diagnostic methods.

METHODS

A prospective cross sectional study was carried out using the provider initiated HIV testing and counselling (PITC) model. HIV rapid test in parallel was used for screening and confirmation was with HIV DNA PCR in children <18 months and Western Blot in children ≥ 18 months.

RESULTS

A total of 600 children were enrolled with ages ranging between one day and 179 months. Male: female ratio was 1.2:1. HIV seroprevalence was 12.3% and after confirmatory tests, the prevalence was 10%. Fourteen (37.8%) of the children aged less 18 months were exposed but not infected. Mother-to-child transmission accounted for 93.3% of cases. Features predictive of HIV infection were diarrhoea, cough, weight loss, ear discharge generalized lymphadenopathy, presence of skin lesions, parotid swelling and oral thrush. About 75% presented in advanced or severe clinical stages of the disease, 56.8% had severe immunodeficiency while 50% had viral loads more than 100,000 copies/ml. Mortality rate was 14.3% among HIV positive compared with 11.3% in HIV negative children but was not significant. Among the HIV positive children, 26.7% were orphans.

CONCLUSIONS

The prevalence rate of HIV infection among new patients screened using the PITC model was high, majority resulting from mother-to-child transmission. Most children presented in advanced stages of the disease and mortality rate among them was high. Though, the study site being a referral centre might have contributed to the high prevalence observed in this study, there is a need to expand access to PMTCT services, ensure implementation of PITC in paediatric settings and expand support services for HIV infected children.

The role of HIV replicative fitness in perinatal transmission of HIV

Perinatal transmission of Human immunodeficiency virus (HIV), also called mother-to-child transmission (MTCT), accounts for 90% of infections in infants worldwide and occurs in 30%-45% of children born to untreated HIV-1 infected mothers. Among HIV-1 infected mothers, some viruses are transmitted from mothers to their infants while others are not. The relationship between virologic properties and the pathogenesis caused by HIV-1 remains unclear. Previous studies have demonstrated that one obvious source of selective pressure in the perinatal transmission of HIV-1 is maternal neutralizing antibodies. Recent studies have shown that viruses which are successfully transmitted to the child have growth advantages over those not transmitted, when those two viruses are grown together. Furthermore, the higher fitness is determined by the gp120 protein of the virus envelope. This suggests that the selective transmission of viruses with higher fitness occurred exclusively, regardless of transmission routes. There are many factors contributing to the selective transmission and HIV replicative fitness is an important one that should not be neglected. This review summarizes current knowledge of the role of HIV replicative fitness in HIV MTCT transmission and the determinants of viral fitness upon MTCT.

Predictors of long-term anti-retroviral therapy effectiveness among Brazilian HIV-1-infected children in a hybrid scenario: what really matters?

The study objective was to evaluate the effectiveness and durability of highly active anti-retroviral therapy (HAART) in perinatally HIV-1-infected children and adolescents and its predictors. A historical cohort study was done at IMIP's Hospital in Recife, Brazil. The study included 195 subjects, 102 (52.3%) had successful response to HAART with a mean time of any HAART use of 4.9 [standard deviation (SD) 2.5; min. 0.7, max. 9.9] years. The time to failure of first HAART was negatively associated with male sex [relative hazard (RH) = 0.5, p = 0.021) and living out of metropolitan area (RH = 0.4, p = 0.009), and associated with Centres for Diseases Control and Prevention (CDC) immunological Stage 1 (RH = 2.9, p = 0.003) and patients who were adherent (RH = 2.2, p = 0.003). HAART success rate and mean time durability was similar to developed country data. However, the main predictors of success were: female sex, living in a metropolitan area, CDC1 immunological category and adherence.

Long-term follow-up outcomes of perinatally HIV-infected adolescents: infection control but school failure

Perinatally human immunodeficiency virus (HIV)-infected children are fighting acquired immune deficiency syndrome (AIDS) and becoming adolescents. The objective of this study was to examine long-term outcomes among perinatally HIV-1-infected adolescents. Cross-sectional clinical and laboratory data were collected for 49 perinatally HIV-infected adolescents followed at the Instituto de Medicina Integral Prof. Fernando Figueira (IMIP's) Hospital from 1987 to 2007. The mean age of these adolescents was 12.5 years, the majority were female (73.5%) with a mean follow-up duration of 9.0 years, 71.4% of adolescents had no signs of HIV infection, 81.6% had normal CD4(+) lymphocyte count, and 53.1% had undetectable HIV viral load. HIV disclosure to the adolescent was reported in 31 (63.3%) participants. The majority were in school (89.8%) but failure and drop-out were reported by 51% and 28.6% of the subjects, respectively. All five domains of quality of life (QOL) measured revealed high scores. The majority of long-term adolescent survivors showed HIV-infection control and high scores of QOL, but with problems in schooling functioning that need early detection and intervention.

Mother-to-child transmission of HIV: pathogenesis, mechanisms and pathways

More than 400,000 children were infected with (HIV-1) worldwide in 2008, or more than 1000 children per day. Mother-to-child transmission (MTCT) of HIV-1 is the most important mode of HIV acquisition in infants and children. MTCT of HIV-1 can occur in utero, intrapartum, and postnatally through breastfeeding. Great progress has been made in preventing such transmission, through the use of antiretroviral prophylactic regimens to the mother during gestation and labor and delivery and to either mother or infant during breast feeding. The timing and mechanisms of transmission, however, are multifactorial and remain incompletely understood. This article summarizes what is known about the pathogenetic mechanisms and routes of MTCT of HIV-1, and includes virologic, immunologic, genetic, and mucosal aspects of transmission.

Outcomes of ventriculoperitoneal shunt insertion in Sub-Saharan Africa

OBJECT

Ventriculoperitoneal (VP) shunts in Sub-Saharan Africa are traditionally associated with high complication rates and poor outcomes. The aim of this study was to review one large institutional experience with VP shunts, to evaluate the feasibility of shunt insertion procedures with acceptable long-term outcomes in Africa, and to identify factors correlated with good and/or poor outcomes.

METHODS

A retrospective study was conducted by reviewing the charts of all children who underwent primary (93%) or subsequent VP shunt insertions at the Kijabe Hospital between November 2004 and March 2007. Epidemiological data, clinical investigations, etiology of the hydrocephalus, details of the VP shunt insertion, outcome at follow-up, and morbidity and mortality data were collected. Outcomes were graded as good, fair, or poor, according to visual, motor, and seizure criteria.

RESULTS

The authors analyzed 593 VP shunt insertions in 574 patients. The sex distribution was 53% male and 47% female. The mean age at shunt insertion was 8.5 months (range 0–309 months). The commonest etiologies for hydrocephalus were spina bifida (43.4%) and postinfectious (27.7%). Follow-up was available in 76% of children, with a mean follow-up period of 8.9 months (range 2–30.5 months). The median patient age was 3.3 months. The overall shunt function rate at 2 years was 65%, and the complication rate per procedure was 20%, with infection encountered in 9.1% and shunt malfunction in 11%. Complications were significantly related to hydrocephalus etiology and to sex (p = 0.03 and p = 0.01, respectively). Overall outcomes were good in 40.2% and poor in 59.8%. Overall mortality in the group was 7.1%. Younger patients who survived had an overall good outcome (p = 0.0001). Only 10% of patients with a head circumference greater than 60 cm had a good outcome.

CONCLUSIONS

Despite limited resources, VP shunt procedures can be carried out in Sub-Saharan Africa with acceptable complication rates and fair long-term outcomes.

Age and gender specific prevalence of HTLV-1

BACKGROUND

The seroprevalence of Human T-cell Leukemia Virus Type 1 (HTLV-1) is female predominant despite the higher incidence of Adult T-cell Leukemia (ATL) in males. If the mother-to-child transmission of HTLV-1 is more common for male infants than in female infants, longer exposure to the virus for males may explain the paradoxically higher incidence of ATL.

OBJECTIVES

To test the hypothesis that the seroprevalence of HTLV-1 is male predominant during adolescence.

STUDY DESIGN

The presence of HTLV-1 antibody in 272,043 blood samples donated to a regional blood bank in an HTLV-1 high-endemic region was assessed.

RESULTS

The entire population of female donors had a significantly higher seroprevalence compared to males (2.05% and 1.80%, respectively, p<0.0001). However, compared with male donors, the carrier rate for female donors was lower for the youngest subgroup (16-19 years, p=0.0011); was similar for the next two age subgroups (20-29 years and 30-39 years); and was significantly higher for the last two age subgroups (40-49 years and over 50-64 years, both p<0.0001). In general, older age subgroups led to higher seroprevalence in both genders.

CONCLUSIONS

HTLV-1 infection is more common for males until after age 20, when male to female sexual transmission becomes likely. This suggests that mother-to-child transmission is more common for males.

To say or not to say: a qualitative study on the disclosure of their condition by human immunodeficiency virus-positive adolescents

PURPOSE

Human immunodeficiency virus (HIV)-positive adolescents face a number of challenges in dealing with their disease, treatment, and developmental tasks. This qualitative study describes some of the reasons why, and the extent to which, adolescents may or may not disclose their condition to others.

METHODS

A semistructured interview lasting 40-110 minutes was conducted with each of 29 adolescents 12-20 years old, 22 female and seven male) living in Switzerland. Interviews were tape recorded and transcribed verbatim. The analysis of the content of interviews allowed us to identify salient topics (e.g., disclosure), which were then explored in detail.

RESULTS

Of 29 participants, eight had not disclosed their condition to anyone outside the family, 19 had disclosed it to good friends, and 16 had disclosed it to some teachers. Four participants had engaged in public disclosure, and six of 10 sexually active teenagers disclosed their status to their partners. The attitudes toward disclosure among younger adolescents were mostly related to those of the parents, particularly the mother. Older adolescents, engaged in their search for autonomy, tended to decide independently what to say and to whom. Although foster/adoptive parents would often encourage disclosure, biological parents, especially HIV-positive mothers, insisted on not disclosing the adolescent's status for fear of stigma.

CONCLUSION

The health care team should systematically address the issue of disclosure with the adolescent and his family (or foster parents), the aim being to balance the right of the adolescent and that adolescent's family to maintain privacy against the concerns of sexual partners, as well as the adolescent's interest in divulging HIV status to relatives, school staff, and friends.

Mother-to-child HIV transmission despite antiretroviral therapy in the ANRS French Perinatal Cohort

OBJECTIVE

To identify factors associated with mother-to-child HIV-1 transmission (MTCT) from mothers receiving antenatal antiretroviral therapy.

DESIGN

The French Perinatal Cohort (EPF), a multicenter prospective cohort of HIV-infected pregnant women and their children.

METHODS

Univariate analysis and logistic regression, with child HIV status as dependent variable, were conducted among 5271 mothers who received antiretroviral therapy during pregnancy, delivered between 1997 and 2004 and did not breastfeed.

RESULTS

The MTCT rate was 1.3% [67/5271; 95% confidence interval (CI), 1.0-1.6]. It was as low as 0.4% (5/1338; 95% CI, 0.1-0.9) in term births with maternal HIV-1 RNA level at delivery below 50 copies/ml. MTCT increased with viral load, short duration of antiretroviral therapy, female gender and severe premature delivery: 6.6% before 33 weeks versus 1.2% at 37 weeks or more (P < 0.001). The type of antiretroviral therapy was not associated with transmission. Intrapartum therapy was associated with four-fold lower MTCT (P = 0.04) in case of virological failure (> 10 000 copies/ml). Elective cesarean section tended to be inversely associated with MTCT in the overall population, but not in mothers who delivered at term with viral load < 400 copies/ml [odds ratio (OR), 0.83; 95% CI, 0.29-2.39; P = 0.37]. Among them, only duration of antenatal therapy was associated with transmission (OR by week, 0.94; 95% CI, 0.90-0.99; P = 0.03).

CONCLUSIONS

Low maternal plasma viral load is the key factor for preventing MTCT. Benefits in terms of MTCT reduction may be expected from early antiretroviral prophylaxis. The potential toxicity of prolonged antiretroviral use in pregnancy should be evaluated.

Does fetal sex affect pregnancy outcome?

BACKGROUND

In maternal fetal medicine, gender differences in outcome are often observed.

OBJECTIVE

This article reviews the fetal sex-dependent differences found in many aspects of pregnancy, from conception through birth.

METHODS

The MEDLINE, EMBASE, and Current Contents databases were searched, for the years 1985 to 2006, using the following Medical Subject Headings and text words: fetal gender, finale, female, sex ratio at birth, pregnancy outcome, preterm birth, and stillbirth. The search was not limited by language. In addition, the bibliographies of known relevant articles were examined to capture any reports not already identified in the electronic search. All reports that provided information on gender differences in pregnancy outcome were included for review.

RESULTS

An extremely high male-to-female ratio was found in fetuses born after very short-duration pregnancy; this level declined around the 20th week and stabilized at term. In the absence of manipulation, both the sex ratio at birth and the population sex ratio have been found to remain consistent. A higher incidence of preterm birth and premature preterm rupture of membranes has been observed in different populations among mothers of male newborns compared with mothers of females. It has been speculated that this higher incidence may be linked to the relatively greater weight at lower gestational age of male newborns versus females. Women carrying male fetuses had higher rates of gestational diabetes mellitus, fetal macrosomia, failure to progress during the first and second stages of labor, cord prolapse, nuchal cord, and true umbilical cord knots. Cesarean sections were also more frequently found among male neonates compared with females.

CONCLUSIONS

Male sex is an independent risk factor for adverse pregnancy outcome. Evidence suggests that females have an advantage over males, with a better outcome in the perinatal period, particularly after preterm birth.

Hepatitis C virus infection

The prevalence of chronic hepatitis C infection in the general paediatric population varies between 0.1 and 15% around the world, with the highest numbers noted in endemic areas of Africa. The risk of viral transmission from an infected mother to her child is approximately 5% and there are currently no effective preventative measures to lower it. All children born to infected mothers should be tested for hepatitis C. The progression to liver damage in infected children is slow. However, in the perspective of 15-20 years of infection or in the presence of other risk factors, such as concomitant chronic disease, a progression to more severe liver damage can be seen. Thus, the use of antiviral treatment may be of importance. Treatment combinations of interferon and ribavirin seem to be at least as effective in children as in adults. However, the negative effect on growth of interferon requires specific attention by paediatricians.

Biological mechanisms of vertical human immunodeficiency virus (HIV-1) transmission

In the absence of interventions, 30-45% of exposed infants acquire human immunodeficiency virus type 1 (HIV-1) through mother-to-child transmission. It remains unclear why some infants become infected while others do not, despite significant exposure to HIV-1 in utero, during delivery and while breastfeeding. Here we discuss the correlates of vertical transmission with an emphasis on factors that increase maternal HIV-1 levels, either systemically or locally in genital secretions and breast milk. Immune responses may influence maternal viral load, and data suggest that maternal neutralising antibodies reduce infection rates. In addition, infants may be capable of mounting HIV-specific cellular immune responses. We propose that both humoral and cellular responses are necessary to reduce infection because cell-free as well as cell-associated virus appears to play a role in vertical transmission. These distinct forms of the virus may be targeted most effectively by different components of the immune system. We also discuss the use of antiretrovirals to reduce transmission, focusing on the mechanisms of action of regimens currently used in developing country settings. We conclude that prevention relies not only on reducing maternal HIV-1 levels within blood, genital tract and breast milk, but also on pre- and/or post-exposure prophylaxis to the infant. However, HIV-1 has the capacity to mutate under drug pressure and rapidly acquires mutations conferring antiretroviral resistance. This review concludes with data on persistence of low-level resistance after delivery as well as recent guidelines for maternal and infant regimens designed to limit resistance.

Effects of infant sex on mother-to-child transmission of HIV-1 according to timing of infection in Zimbabwe

We examined the relationship between sex and the risk of intrauterine, intrapartum and postnatal HIV transmission among 4495 infants born to HIV-infected mothers in Harare, Zimbabwe. Intrauterine transmission was 8.6%, and consistent with other studies was higher among girl than boy infants (AOR 1.53; 95% CI 1.23-1.91). Unlike previous studies, we observed no independent effect of infant sex on intrapartum or breastfeeding-associated HIV transmission. Sex-specific postnatal prevention strategies are not warranted in this population.

Gender differences in human immunodeficiency virus (HIV) RNA and CD4 cell counts among new entrants to HIV care

Clinic database extraction identified 806 new entrants to human immunodeficiency virus (HIV) care in Cleveland, OH, USA. At entry, women had higher CD4 counts and lower HIV RNA levels than men (mean, 388 vs. 310 cells/microL, and 8.94 x 10(4) vs. 1.27 x 10(5) copies/mL, respectively), but the proportion of entrants with category C illnesses, category B conditions, sexually transmitted diseases and CD4 counts < 200 microL did not differ between genders. Hepatitis B seroprevalence was higher in men (8.7% vs. 0.6%), but there was no difference in hepatitis C prevalence. Whether women in Cleveland seek HIV care earlier, or whether early markers of HIV disease differ between the genders, remains to be determined.

Higher In Utero and Perinatal HIV Infection Risk in Girls Than Boys

OBJECTIVE

This study analyzed mother-to-child HIV transmission rates by sex and exposure time for babies born to HIV-infected, untreated African women.

METHODS

Data were analyzed from 2 independent studies done in Malawi during the 1990s. Infections were established by polymerase chain reaction on blood samples. Odds ratios (ORs) for transmission were examined by period at risk: in utero (infected in umbilical cord blood), perinatal (infected in 1st postnatal blood > or =4 weeks), and postnatal (later postnatal infection).

RESULTS

Among 1394 singleton births, girls were more likely to become infected than boys. For in utero transmission, the OR was 1.4 (95% CI: 0.9 to 2.2). For transmission during early life (umbilical cord blood not available) the OR was 2.7 (95% CI: 1.5 to 4.9). However, transmission risks in the perinatal and postnatal infection periods did not differ in boys and girls. Among 303 tested twin-birth pairs, girls were at higher risk than boys for in utero (OR: 2.6; 95% CI: 1.2 to 5.8) and perinatal (OR: 1.9; 95% CI: 1.0 to 3.7) infection. Recognized mother-to-child transmission risk factors did not explain the higher risk of infection in girls.

CONCLUSIONS

Girls were at higher risk of early (in utero and perinatal) HIV infection than boys. It is proposed that minor histocompatibility reactions between maternal lymphocytes and infant Y chromosome-derived antigens reduce the risk of HIV transmission in boys.

Lower mother-to-child HIV-1 transmission in boys is independent of type of delivery and antiretroviral prophylaxis: the Italian Register for HIV Infection in Children

The relationship between infant's gender and rate of HIV-1 mother-to-child transmission (MTCT) was evaluated in a prospective cohort of 4151 children (2166 boys and 1985 girls) born to HIV-1-infected mothers enrolled in the Italian Register for HIV Infection in Children. Logistic regression models were performed to estimate crude odds ratios (ORs) and adjusted odds ratios (AORs) and 95% CIs for factors potentially influencing MTCT separately for the period 1985-1995 and the period 1996-2001. To evaluate rates of MTCT by gender in specific subgroups, separate logistic regression models by mode of delivery and antiretroviral prophylaxis were performed. Among children born in 1985-1995, 15.5% boys (95% CI: 13.6-17.7) and 17.9% girls (95% CI: 15.7-20.3) were infected (P = 0.1181). After 1995, a lower proportion of boys (3.1% [95% CI: 2.0-4.4]; AOR: 0.43 [95% CI: 0.26-0.71], P = 0.0008) than girls (AOR: 6.3%, 95% CI: 4.8-8.1) was infected. Lower AORs for boys persisted independently of elective cesarean delivery (AOR: 0.31, 95% CI: 0.14-0.71); other than elective cesarean (AOR: 0.38, 95% CI: 0.19-0.78) and antiretroviral prophylaxis (zidovudine monotherapy (AOR: 0.11, 95% CI: 0.03-0.38); none (AOR: 0.43, 95% CI: 0.21-0.90). No difference was observed when combined therapy in the mother was administered (AOR: 1.14, 95% CI: 0.30-4.32), but results were likely to be biased by the very low rate of infected children in this group. A lower proportion of HIV-1-infected boys in children born after 1995 was found. Factor(s) intrinsic to gender (rather than type of delivery or maternal antiretroviral prophylaxis) may be involved, because the risk of infection in boys was lower independent of interventions. A possible explanation is that, among infected fetuses, more girls survive up to the end of pregnancy and may take advantage of the benefits of preventive strategies.