Maternal-fetal microtransfusions and HIV-1 mother-to-child transmission in Malawi

Low birth weight among infants and pregnancy outcomes among women living with HIV and HIV-negative women in Rwanda

Introduction

In utero exposure to HIV and/or triple antiretroviral therapy (ART) have been shown to be associated with preterm births and low birth weight (LBW), but data from low-resources settings with high burden of HIV remain limited. This study utilized retrospective data to describe pregnancy outcomes among Rwandan women living with HIV (WLHIV) and HIV-negative women and to assess the association of HIV and ART with LBW.

Methods

This study used data from a large cohort of WLHIV and HIV-negative women in Rwanda for a cross-sectional analysis. Retrospective data were collected from antenatal care (ANC), delivery, and Prevention of Mother to Child Transmission (PMTCT) registries within the Central Africa International Epidemiology Databases to Evaluate AIDS (CA-IeDEA) in Rwanda. Data from women with documented HIV test results and known pregnancy outcomes were included in the analysis. Analyses for predictors of LBW (< 2,500 g) were restricted to singleton live births. Logistic models were used to identify independent predictors and estimate the odd ratios (OR) and 95% confidence intervals (CI) measuring the strength of their association with LBW.

Results and discussion

Out of 10,608 women with known HIV status and with documented pregnancy outcomes, 9.7% (n = 1,024) were WLHIV. We restricted the sample to 10,483 women who had singleton live births for the analysis of the primary outcome, LBW. Compared with HIV-negative women, WLHIV had higher rates of stillbirth, preterm births, and LBW babies. Multivariable model showed that WLHIV and primigravidae had higher odds of LBW. Lower maternal weight and primigravidae status were associated with greater odds of LBW. Among WLHIV, the use of ART was associated with significantly lower odds of LBW in a bivariate analysis. Even in a sample of relatively healthier uncomplicated pregnancies and women who delivered in low-risk settings, WLHIV still had higher rates of poor pregnancy outcomes and to have LBW infants compared to women without HIV. Lower maternal weight and primigravidae status were independently associated with LBW. Given that supplementary nutrition to malnourished pregnant women is known to decrease the incidence of LBW, providing such supplements to lower-weight WLHIV, especially primigravidae women, might help reduce LBW.

The risk of sexual transmission of HIV in individuals with low-level HIV viraemia: a systematic review

BACKGROUND

The risk of sexual transmission of HIV from individuals with low-level HIV viraemia receiving antiretroviral therapy (ART) has important public health implications, especially in resource-limited settings that use alternatives to plasma-based viral load testing. This Article summarises the evidence related to sexual transmission of HIV at varying HIV viral load levels to inform messaging for people living with HIV, their partners, their health-care providers, and the wider public.

METHODS

We conducted a systematic review and searched PubMed, MEDLINE, Cochrane Central Register of Controlled Trials, Embase, Conference Proceedings Citation Index-Science, and WHO Global Index Medicus, for work published from Jan 1, 2010 to Nov 17, 2022. Studies were included if they pertained to sexual transmission between serodiscordant couples at various levels of viraemia, the science behind undetectable=untransmittable, or the public health impact of low-level viraemia. Studies were excluded if they did not specify viral load thresholds or a definition for low-level viraemia or did not provide quantitative viral load information for transmission outcomes. Reviews, non-research letters, commentaries, and editorials were excluded. Risk of bias was evaluated using the ROBINS-I framework. Data were extracted and summarised with a focus on HIV sexual transmission at varying HIV viral loads.

FINDINGS

244 studies were identified and eight were included in the analysis, comprising 7762 serodiscordant couples across 25 countries. The certainty of evidence was moderate; the risk of bias was low. Three studies showed no HIV transmission when the partner living with HIV had a viral load less than 200 copies per mL. Across the remaining four prospective studies, there were 323 transmission events; none were in patients considered stably suppressed on ART. Among all studies there were two cases of transmission when the index patient's (ie, patient with previously diagnosed HIV infection) most recent viral load was less than 1000 copies per mL. However, interpretation of both cases was complicated by long intervals (ie, 50 days and 53 days) between the transmission date and the most recent index viral load result.

INTERPRETATION

There is almost zero risk of sexual transmission of HIV with viral loads of less than 1000 copies per mL. These data provide a powerful opportunity to destigmatise HIV and promote adherence to ART through dissemination of this positive public health message. These findings can also promote access to viral load testing in resource-limited settings for all people living with HIV by facilitating uptake of alternative sample types and technologies.

FUNDING

Bill & Melinda Gates Foundation.

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.

Monitoring Prevention Impact of Mother-to-Child Transmission of HIV in Concentrated Epidemics With Program and Survey Data

Background

The prevention of mother-to-child transmission (PMTCT) of HIV program was introduced in Vietnam in 2005. Despite the scaling up of PMTCT programs, the rate of mother-to-child HIV transmission in Vietnam was estimated as high as 20% in 2013.

Objective

The objective of this study was to assess the outcomes of PMTCT and identified factors associated with mother-to-child transmission and infant survival using survey and program data in a high HIV burden province in Vietnam.

Methods

This community-based retrospective cohort study observed pregnant women diagnosed with HIV infection in Thai Nguyen province from October 2008 to December 2012. Data were collected through interviews using a structured questionnaire and through reviews of log books and medical charts in antenatal care and HIV clinics. Logistic regression and survival analysis were used to analyze data using Stata (StataCorp).

Results

A total of 172 pregnant women living with HIV were identified between 2008 and 2012. Most of these women had acquired the HIV infection from their husband (77/119, 64.7%). Significant improvement in the PMTCT program was documented, including reduction in late diagnosis of HIV for pregnant women from 62.5% in 2008 to 30% in 2012. Access to antiretrovirals (ARVs) improved, increasing from a rate of 18.2% (2008) to 70.0% (2011) for mothers and from 36.4% (2008) to 93.3% (2012) for infants. For infants, early diagnosis within 2 months of birth reached 66.7% in 2012 compared with 16.7% in 2009. Transmission rate reduced from 27.3% in 2008 to 6.7% in 2012. Late diagnosis was associated with increased risk for HIV transmission (odds ratio [OR] 14.7, 95% CI 1.8-121.4, P=.01), whereas ARV therapy for mother and infant in combination with infant formula feeding were associated with reduced risk for HIV transmission (OR 0.01, 95% CI 0.001-0.1; P<.001). Overall survival rate for HIV-exposed infants at 12 months was 97.7%.

Conclusions

A combination of program and survey data measured the impact of prevention of HIV transmission from mother-to-child interventions. Significant improvement in access to the interventions was documented in Thai Nguyen province. However, factors that increased the risk of HIV transmission, such as late diagnosis, remain to be addressed.

The role of cell-associated virus in mother-to-child HIV transmission

Mother-to-child transmission (MTCT) of human immunodeficiency virus (HIV) continues to contribute to the global burden of disease despite great advances in antiretroviral (ARV) treatment and prophylaxis. In this review, we discuss the proposed mechanisms of MTCT, evidence for cell-free and cell-associated transmission in different routes of MTCT, and the impact of ARVs on virus levels and transmission. Many population-based studies support a role for cell-associated virus in transmission and in vitro studies also provide some support for this mode of transmission. However, animal model studies provide proof-of-principle that cell-free virus can establish infection in infants, and studies of ARVs in HIV-infected pregnant women show a strong correlation with reduction in cell-free virus levels and protection. ARV treatment in MTCT potentially provides opportunities to better define the infectious form of virus, but these studies will require better tools to measure the infectious cell reservoir.

HLA-G 14 bp deletion/insertion polymorphism and mother-to-child transmission of HIV

The human leukocyte antigen HLA-G, highly expressed at the maternal-fetal interface, has a pivotal role in mediating immune tolerance. In this study we investigated the influence of HLA-G 14 bp insertion polymorphism in human immunodeficiency virus (HIV)-1 mother-to-child HIV-1 transmission. The 14 bp insertion polymorphism was analyzed among 99 HIV-1 positive mothers and 329 infants born to HIV-positive mothers in Zambia, among whom vertical transmission status and timing had been determined. HLA-G 14 bp insertion polymorphism was detected using a custom TaqMan single nucleotide polymorphisms (SNPs) genotyping assay. Logistic regression was conducted to examine the associations between HLA-G alleles and the risk of HIV transmission. The 14 bp insertion allele was more frequent in HIV exposed-uninfected (EU) infants than in infected infants, and was associated with reduced risk of both in utero (IU) and intrapartum (IP) HIV transmission, after adjusting for maternal cluster of differentiation 4 (CD4) cell count and plasma viral load. Maternal HLA-G 14 bp insertion genotype and HLA-G concordance between mother and child were not associated with the risk of perinatal HIV transmission. The presence of the 14 bp insertion associates with protection toward IU and IP HIV infection in children from Zambia, suggesting that HLA-G could be involved in the vertical transmission of HIV.

KIR2DS4 allelic variants: Differential effects on in utero and intrapartum HIV-1 mother-to-child transmission

KIR2DS4 is the only activating gene within the A haplotype, and alleles of KIR2DS4 can encode either functional (KIR2DS4-f) or non-functional (KIR2DS4-v) variants. To establish the role of KIR2DS4 in the context of HIV-1 mother-to-child transmission, we KIR genotyped 145 HIV-1 non-transmitting mothers (NT) and their exposed uninfected infants (EU), and 72 HIV-1 transmitting mothers (TR) and their infected infants [intrapartum (IP), in utero (IU) or IU2 (an IU-enriched infected group)]. The frequency of KIR2DS4-v was significantly higher in IU2 infants compared to EU infants (P=0.022, OR=2.88); this association was more significant amongst AA haplotypes (P=0.004, OR=18.4). Possession of KIR2DS4-f in the mother with absence in the infant (M+I- discordance) was associated with a higher risk of IP transmission (P=0.005, OR=3.84); whilst in M-I+ discordance, infant possession of KIR2DS4-v was associated with increased risk of IU acquisition (P=0.002; OR=6.40). This study highlights the importance of KIR2DS4 in HIV-1 transmission/acquisition.

Short communication: HIV type 1 subtype C variants transmitted through the bottleneck of breastfeeding are sensitive to new generation broadly neutralizing antibodies directed against quaternary and CD4-binding site epitopes

Mother-to-child transmission of HIV-1 subtype C can occur in utero, intrapartum, or via breast milk exposure. While not well understood, there are putative differences in the mechanisms involved with the distinct routes of vertical HIV transmission. Here, we address the question of whether specific viral characteristics are common to variants transmitted through breastfeeding that may facilitate evasion of innate or adaptive immune responses. We amplified the envelope gene (env) from the plasma of six infants during acute infection who were infected with HIV-1 subtype C through breastfeeding, and from three available matched maternal samples. We sequenced the full-length env genes in these subjects revealing heterogeneous viral populations in the mothers and homogeneous populations in the infants. In five infants, the viral population arose from a single variant, while two variants were detected in the remaining infant. Infant env sequences had fewer N-linked glycosylation sites and shorter sequences than those of the available matched maternal samples. Though the small size of the study precluded our ability to test statistical significance, these results are consistent with selection for virus with shorter variable loops and fewer glycosylation sites during transmission of HIV-1 subtype C in other settings. Transmitted envs were resistant to neutralization by antibodies 2G12 and 2F5, but were generally sensitive to the more broadly neutralizing PG9, PG16, and VRC01, indicating that this new generation of broadly neutralizing monoclonal antibodies could be efficacious in passive immunization strategies.

Postnatally-transmitted HIV-1 Envelope variants have similar neutralization-sensitivity and function to that of nontransmitted breast milk variants

Background

Breastfeeding is a leading cause of infant HIV-1 infection in the developing world, yet only a minority of infants exposed to HIV-1 via breastfeeding become infected. As a genetic bottleneck severely restricts the number of postnatally-transmitted variants, genetic or phenotypic properties of the virus Envelope (Env) could be important for the establishment of infant infection. We examined the efficiency of virologic functions required for initiation of infection in the gastrointestinal tract and the neutralization sensitivity of HIV-1 Env variants isolated from milk of three postnatally-transmitting mothers (n=13 viruses), five clinically-matched nontransmitting mothers (n=16 viruses), and seven postnatally-infected infants (n = 7 postnatally-transmitted/founder (T/F) viruses).

Results

There was no difference in the efficiency of epithelial cell interactions between Env virus variants from the breast milk of transmitting and nontransmitting mothers. Moreover, there was similar efficiency of DC-mediated trans-infection, CCR5-usage, target cell fusion, and infectivity between HIV-1 Env-pseudoviruses from nontransmitting mothers and postnatal T/F viruses. Milk Env-pseudoviruses were generally sensitive to neutralization by autologous maternal plasma and resistant to breast milk neutralization. Infant T/F Env-pseudoviruses were equally sensitive to neutralization by broadly-neutralizing monoclonal and polyclonal antibodies as compared to nontransmitted breast milk Env variants.

Conclusion

Postnatally-T/F Env variants do not appear to possess a superior ability to interact with and cross a mucosal barrier or an exceptional resistance to neutralization that define their capability to initiate infection across the infant gastrointestinal tract in the setting of preexisting maternal antibodies.

HIV-1 Nef breaches placental barrier in rat model

The vertical transmission of HIV-1 from the mother to fetus is known, but the molecular mechanism regulating this transmission is not fully characterized. The fetus is highly protected by the placenta, which does not permit microbial pathogens to cross the placental barrier. In the present study, a rat model was established to observe the effect of HIV-1 protein Nef on placental barrier. Evans blue dye was used to assay permeability of placental barrier and fourteen day pregnant Sprague Dawley rats were injected intravenously with 2% Evans blue dye along with various concentrations of recombinant Nef. After an hour, animals were sacrificed and dye migration was observed through the assimilation of peripheral blood into fetus. Interestingly, traces of recombinant Nef protein were detected in the embryo as well as amniotic fluid and amniotic membrane along with placenta and uterus. Our study indicates that recombinant HIV-1-Nef protein breaches the placental barrier and allows the migration of Evans blue dye to the growing fetus. Further the concentration of Nef protein in blood is directly proportional to the intensity of dye migration and to the amount of Nef protein detected in uterus, placenta, amniotic membrane, amniotic fluid and embryo. Based on this study, it can be concluded that the HIV-1 Nef protein has a direct effect on breaching of the placental barrier in the model we have established in this study. Our observations will be helpful to understand the molecular mechanisms related to this breach of placental barrier by Nef in humans and may be helpful to identify specific Nef inhibitors.

Pathogenesis of hepatitis C during pregnancy and childhood

The worldwide prevalence of HCV infection is between 1% and 8% in pregnant women and between 0.05% and 5% in children. Yet the pathogenesis of hepatitis C during pregnancy and in the neonatal period remains poorly understood. Mother-to-child transmission (MTCT), a leading cause of pediatric HCV infection, takes place at a rate of <10%. Factors that increase the risk of MTCT include high maternal HCV viral load and coinfection with HIV-1 but, intriguingly, not breastfeeding and mode of delivery. Pharmacological prevention of MTCT is not possible at the present time because both pegylated interferon alfa and ribavirin are contraindicated for use in pregnancy and during the neonatal period. However, this may change with the recent introduction of direct acting antiviral agents. This review summarizes what is currently known about HCV infection during pregnancy and childhood. Particular emphasis is placed on how pregnancy-associated immune modulation may influence the progression of HCV disease and impact MTCT, and on the differential evolution of perinatally acquired HCV infection in children. Taken together, these developments provide insights into the pathogenesis of hepatitis C and may inform strategies to prevent the transmission of HCV from mother to child.

Elevated cytokine and chemokine levels in the placenta are associated with in-utero HIV-1 mother-to-child transmission

OBJECTIVE

To determine whether there is an association between cytokine and chemokine levels in plasma isolated from the placenta and HIV-1 mother-to-child transmission (MTCT).

DESIGN

We designed a case-control study of HIV-infected, pregnant women enrolled in the Malaria and HIV in Pregnancy cohort. Participants were recruited in Blantyre, Malawi, from 2000 to 2004. Patients were women whose children were HIV-1 DNA-positive at birth (in-utero MTCT) or HIV-1 DNA-negative at birth and HIV-1 DNA-positive at 6 weeks postpartum (intrapartum MTCT); controls were women whose children were HIV-1 DNA-negative both at birth and 6 weeks postpartum.

METHODS

After delivery, blood was isolated from an incision on the basal plate of the placenta. We used a Bio-Plex human cytokine assay (Bio-Rad, Hercules, California USA) to simultaneously quantify 27 cytokines, chemokines and growth factors in placental plasma. HIV-1 RNA copies were quantified with the Roche Amplicor kit.

RESULTS

Levels of interleukin (IL) 4, IL-5, IL-6, IL-7, IL-9, eotaxin, IL-1Ra and interferon gamma-induced protein 10 (IP-10) were significantly elevated in placental plasma isolated from cases of in-utero HIV-1 MTCT. In contrast, only granulocyte colony-stimulating factor was elevated in placental plasma isolated from cases of intrapartum MTCT. After adjusting for maternal age, gestational age and peripheral CD4(+) T-cell count, every log(10) increase in placental IP-10 was associated with a three-fold increase in the prevalence of in-utero HIV-1 MTCT.

CONCLUSION

Elevated cytokine and chemokine levels in placental plasma were associated with in-utero and not intrapartum MTCT. IP-10, which is both a T-cell chemokine and potentiator of HIV-replication, was robustly and independently associated with prevalent, in-utero MTCT.

The microbiologic safety of umbilical cord blood transfusion for children with severe anemia in Mombasa, Kenya

BACKGROUND

Severe anemia requiring blood transfusion is common in hospitalized young children in sub-Saharan Africa but blood is often in short supply. Umbilical cord blood may be a useful source of blood if microbiologic safety concerns can be addressed.

STUDY DESIGN AND METHODS

Cord blood, donated on the labor ward at the provincial hospital in Mombasa, was cultured soon after collection (screening culture) and after a period of storage (poststorage culture). Conventional blood transfused to children at the hospital was cultured only at the time of issue (poststorage culture). Maternal sera (cord blood) and conventional blood donations were also screened for transfusion-transmitted infection.

RESULTS

At poststorage culture, the overall contamination rate of cord blood was one-third that of conventional blood (13/449 vs. 38/434; odds ratio [OR], 0.31; 95% confidence interval [CI], 0.15-0.61) and for bacteria of high pathogenic potential it was half that of conventional blood (4/449 vs. 7/434; OR, 0.55; 95% CI, 0.12-2.18). Screening cultures were positive in 50% (2/4) of cord blood packs where an organism of high pathogenic potential was isolated at poststorage culture. Cord blood donors had a lower seroreactivity than conventional donors for human immunodeficiency virus (OR, 0.63; 95% CI, 0.29-1.18), hepatitis B virus (OR, 0.32; 95% CI, 0.16-0.59), and hepatitis C virus (OR, 0.20; 95% CI, 0.24-0.76). For syphilis, initial seroreactivity in cord blood donors was 3.8% compared to 1.8% in conventional blood donors (OR, 2.10; 95% CI, 1.15-3.60) but was 0.5% after retesting.

CONCLUSION

With respect to bacterial contamination and seroreactivity for transfusion-transmitted infection, the safety of cord blood in Mombasa compares favorably with conventional blood. Clinical trials of cord blood transfusion are justified.

Different regions of HIV-1 subtype C env are associated with placental localization and in utero mother-to-child transmission

HIV infections are initiated by a limited number of variants that diverge into a diverse quasispecies swarm. During in utero mother-to-child transmission (IU MTCT), transmitted viral variants must pass through multiple unique environments, and our previously published data suggest a nonstochastic model of transmission. As an alternative to a stochastic model of viral transmission, we hypothesize that viral selection in the placental environment influences the character of the viral quasispecies when HIV-1 is transmitted in utero. To test this hypothesis, we used single-template amplification to isolate HIV-1 envelope gene (env) sequences from both peripheral plasma and the placentas of eight nontransmitting (NT) and nine IU-transmitting participants. Statistically significant compartmentalization between peripheral and placental HIV-1 env was detected in one of the eight NT cases and six of the nine IU MTCT cases. In addition, viral sequences isolated from IU MTCT placental tissue showed variation in env V1 loop lengths compared to matched maternal sequences, while NT placental env sequences did not. Finally, comparison of env sequences from NT and IU MTCT participants indicated statistically significant differences in Kyte-Doolittle hydropathy in the signal peptide, C2, V3, and C3 regions. Our working hypothesis is that the hydropathy differences in Env associated with IU MTCT alter viral cellular tropism or affinity, allowing HIV-1 to efficiently infect placentally localized cells.

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.

The genetic bottleneck in vertical transmission of subtype C HIV-1 is not driven by selection of especially neutralization-resistant virus from the maternal viral population

Subtype C human immunodeficiency virus type 1 (HIV-1C) continues to cause the majority of new cases of mother-to-child transmission (MTCT), and yet there are limited data on HIV-1C transmission. We amplified env from plasma RNA for 19 HIV-1C MTCT pairs, 10 transmitting in utero (IU) and 9 transmitting intrapartum (IP). There was a strong genetic bottleneck between all mother-infant pairs, with a majority of transmission events involving the transmission of a single virus. env genes of viruses transmitted to infants IP, but not IU, encoded Env proteins that were shorter and had fewer putative N-linked glycosylation sites in the V1-V5 region than matched maternal sequences. Viruses pseudotyped with env clones representative of each maternal and infant population were tested for neutralization sensitivity. The 50% inhibitory concentration of autologous serum was similar against both transmitted (infant) and nontransmitted (maternal) viruses in a paired analysis. Mother and infant Env proteins were also similar in sensitivity to soluble CD4, to a panel of monoclonal antibodies, and to heterologous HIV-1C sera. In addition, there was no difference in the breadth or potency of neutralizing antibodies between sera from 50 nontransmitting and 23 IU and 23 IP transmitting HIV-1C-infected women against four Env proteins from heterologous viruses. Thus, while a strong genetic bottleneck was detected during MCTC, with viruses of shorter and fewer glycosylation sites in env present in IP transmission, our data do not support this bottleneck being driven by selective resistance to antibodies.

Prevention of mother-to-child transmission of HIV-1: the role of cesarean delivery

The risk of mother-to-child transmission (MTCT) of HIV can be reduced through cesarean delivery prior to the onset of labor and prior to rupture of the membranes (elective cesarean delivery [ECD]). As a result of this evidence, the American College of Obstetricians and Gynecologists and the Department of Health and Human Services Panel on Treatment of HIV-Infected Pregnant Women and Prevention of Perinatal Transmission developed guidelines recommending ECD for HIV-infected women with plasma viral loads of more than 1000 copies/mL. Since the release of the recommendations, an increase in ECD has been seen among HIV-infected women in the United States. This article discusses the evidence on efficacy of ECD, current recommendations in the United States, and risks and morbidity related to ECD. Although the benefit of ECD in preventing MTCT of HIV is substantial, some questions remain. Specifically, the benefit of ECD for women with very low viral loads or for women using combination antiretroviral regimens is unclear, as is the timeframe after onset of labor or rupture of membranes within which ECD will still confer preventive benefits.

Chikungunya virus infection during pregnancy, Reunion, France, 2006

Mother-to-child transmission of chikungunya virus was reported during the 2005-2006 outbreak on Reunion Island, France. To determine the effects of this virus on pregnancy outcomes, we conducted a study of pregnant women in Reunion in 2006. The study population was composed of 1,400 pregnant women (628 uninfected, 658 infected during pregnancy, 27 infected before pregnancy, and 87 infected on unknown dates). We compared pregnancy outcomes for 655 (628 + 27) women not infected during pregnancy with 658 who were infected during pregnancy. Infection occurred during the first trimester for 15% of the infected women, the second for 59%, and the third for 26%. Only hospital admission during pregnancy differed between infected and uninfected women (40% vs. 29%). Other outcomes (cesarean deliveries, obstetric hemorrhaging, preterm births, stillbirths after 22 weeks, birthweight, congenital malformations, and newborn admissions) were similar. This virus had no observable effect on pregnancy outcomes.

Chikungunya virus infection during pregnancy, Reunion, France, 2006

Except for prenatal hospital admissions for those infected, this virus had no effect on outcomes.

Mother-to-child transmission of chikungunya virus was reported during the 2005–2006 outbreak on Réunion Island, France. To determine the effects of this virus on pregnancy outcomes, we conducted a study of pregnant women in Réunion in 2006. The study population was composed of 1,400 pregnant women (628 uninfected, 658 infected during pregnancy, 27 infected before pregnancy, and 87 infected on unknown dates). We compared pregnancy outcomes for 655 (628 + 27) women not infected during pregnancy with 658 who were infected during pregnancy. Infection occurred during the first trimester for 15% of the infected women, the second for 59%, and the third for 26%. Only hospital admission during pregnancy differed between infected and uninfected women (40% vs. 29%). Other outcomes (cesarean deliveries, obstetric hemorrhaging, preterm births, stillbirths after 22 weeks, birthweight, congenital malformations, and newborn admissions) were similar. This virus had no observable effect on pregnancy outcomes.

Acute HIV infection among pregnant women in Malawi

There are limited data on acute HIV infection (AHI) prevalence during pregnancy. Malawian pregnant women admitted in the third trimester and meeting eligibility criteria underwent dual HIV rapid antibody testing. AHI prevalence was retrospectively detected through HIV RNA pooling of seronegative plasma. Among 3,825 pregnant women screened, dual HIV rapid testing indicated that 30.2% were HIV positive, 69.7% were HIV negative, and 0.1% were indeterminate. Sensitivity and specificity of dual rapid testing was 99.0% and 98.7%, respectively. Of 2,666 seronegative specimens, 2,327 had samples available for HIV RNA pooling; 5 women (0.21%) (95% confidence interval, 0.03-0.40%) had AHI with a median peripartum viral load of 1,324,766 copies/mL. Pregnant women are at risk for AHI, warranting counseling of all women and their sexual partners about incident HIV during pregnancy. Dual HIV rapid tests have high sensitivity and specificity. HIV testing should be repeated in the third trimester and/or at delivery.

Antiretroviral therapy (ART) for treating HIV infection in ART-eligible pregnant women

BACKGROUND

This systematic review focuses on antiretroviral therapy (ART) for treating human immunodeficiency virus (HIV) infection in ART-eligible pregnant women. Mother-to-child transmission (MTCT) is the primary means by which children worldwide acquire HIV infection. MTCT occurs during three major timepoints during pregnancy and the postpartum period: in utero, intrapartum, and during breastfeeding. Strategies to reduce MTCT focus on these periods of exposure and include maternal and infant use of ART, caesarean section before onset of labour or rupture of membranes, and complete avoidance of breastfeeding. Where these combined interventions are available, the risk of MTCT is as low as 1-2%. Thus, ART used among mothers who require treatment of HIV for their own health also plays a significant role in decreasing MTCT.This review is one in a series of systematic reviews performed in preparation for the revision of the 2006 World Health Organization (WHO) Guidelines regarding "Antiretroviral Drugs for Treating Pregnant Women and Preventing HIV Infection in Infants" and "Antiretroviral therapy (ART) for HIV Infections in Adults and Adolescents." The findings from these reviews were discussed with experts, key stakeholders, and country representatives at the 2009 WHO guideline review meeting. The resulting WHO 2009 "rapid advice" preliminary guidance on adult and adolescent ART now recommends lifelong treatment for all adults with HIV infection and CD4 counts <350 cells/mm(3). These recommendations also apply to pregnant women who are HIV-infected and they place a high value on early ART to benefit the mother's own health (WHO 2009). The "rapid advice" preliminary guidance also aims to minimize side effects for mothers and their infants (WHO 2009).

OBJECTIVES

Our objective was to assess the current literature regarding the treatment of HIV infection in pregnant women who are clinically or immunologically eligible for ART. This review includes an evaluation of the optimal time to start therapy in relation to the woman's laboratory parameters and/or gestational age. It also includes an analysis of which specific antiretroviral medications to start in women who are not yet on ART and which agents to continue in women who are already on ART.

SEARCH STRATEGY

In June 2009, electronic searches were undertaken in these databases: Cochrane's "CENTRAL," EMBASE, PubMed, LILACS, and Web of Science/Web of Social Science. Hand searches were performed of the reference lists of all pertinent reviews and studies identified. Abstracts from relevant conferences were searched. Experts in the field were contacted to locate additional studies. The search strategy was iterative.

SELECTION CRITERIA

We selected randomized controlled trials and observational studies that evaluated pregnant women with HIV infection who were eligible for ART according to criteria defined by the WHO guideline review committee. Studies were included in the systematic review when a comparison group was clearly defined and where the intervention comprised triple ART. For a study to be considered, each medication in the ART regimen needed to be clearly described.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the selected studies for relevance and inclusion. Relevant data was then extracted from included studies, and the risk of bias assessed. In each included study, the relative risk (RR) for the intervention versus the comparison group was calculated for each outcome, as appropriate, with 95% confidence intervals (CIs).

MAIN RESULTS

To our knowledge, there are no randomized controlled trials or observational studies that address the optimal time to start antiretroviral drugs in ART-eligible pregnant women in relation to the woman's laboratory parameters and/or gestational age. The medications to continue in ART-eligible pregnant women who are already receiving ART also have not been evaluated systematically in the current literature. The long-term mortality of HIV-positive pregnant women on ART for their own health, and the long-term virologic or clinical efficacy of ART in treating them, has not been evaluated in randomized clinical trials. In this review, surrogate outcomes for long-term mortality and virologic and clinical efficacy (e.g. MTCT and infant HIV transmission or death) were evaluated to determine the efficacy of specific antiretroviral regimens to start in women who are not yet on ART.Three randomized controlled trials and six observational studies were selected. No studies addressed comparative maternal mortality, which regimens to continue in women already on ART, or the laboratory parameters and gestational age at which to start therapy. The use of zidovudine (AZT), lamivudine (3TC) and lopinavir/ritonavir (LPV-r) starting at 28-36 weeks gestation in a breastfeeding population reduced infant HIV-transmission or death at 12 months compared to a short-course regimen (RR 0.64, 95% CI: 0.44-0.92) (deVincenzi, 2009). Starting AZT, 3TC, and nevirapine (NVP) at 34 weeks in a mixed-feeding population reduced infant HIV-transmission or death at 7 months compared to a short-course regimen (RR 0.39, 95% CI: 0.12-0.85) (Bae, 2008).In the Mma Bana study (a randomized controlled trial in a breastfeeding population) there was no difference in MTCT at six months between the AZT/3TC/LPV-r and AZT, 3TC, and abacavir (ABC) arms (RR 0.17, 95% CI: 0.02-1.44) (Shapiro, 2009). Both regimens also showed 92-95% efficacy in virologic suppression at delivery and during the breastfeeding period. In the Kesho Bora study there was a significant difference in MTCT at 12 months between breastfeeding women who initiated AZT/3TC/LPV-r starting between 28 and 36 weeks and those receiving a short course regimen (RR 0.58, 95% CI: 0.34-0.97) (deVincenzi, 2009). MTCT also decreased significantly when AZT/3TC/NVP was compared with a short-course regimen at seven months in a feeding intervention study (RR 0.15, 95% CI: 0.04-0.62) (Bae, 2008) and 12 months in a population where either exclusive breastfeeding or replacement feeding was encouraged (RR 0.14, CI: 0.04-0.47) (Ekouevi, 2008).In the Mma Bana study, there was increased risk of prematurity among infants born to women receiving AZT/3TC/LPV-r (RR 1.52, CI: 1.07- 2.17) compared with AZT/3TC/ABC (Shapiro, 2009). Ekouevi 2008 showed higher rates of infant low birth weight on AZT/3TC/NVP started at 24 weeks compared to a short course regimen started between 32 and 36 weeks (RR 1.81, 95% CI: 1.09- 3.0). Tonwe-Gold 2007 showed an increase in maternal severe adverse events among the women receiving AZT/3TC/NVP compared with a short-course regimen (RR 25.33, CI 1.49- 340.51).

AUTHORS' CONCLUSIONS

In ART-eligible pregnant women with HIV infection, ART is a safe and effective means of providing maternal virologic suppression, decreasing infant mortality, and reducing MTCT. Specifically, AZT/3TC/NVP, AZT/3TC/LPV-r, and AZT/3TC/ABC have been shown to decrease MTCT. More research is needed regarding the use of specific regimens and their maternal and infant side-effect profiles.

Antibody-dependent transplacental transfer of malaria blood-stage antigen using a human ex vivo placental perfusion model

Prenatal exposure to allergens or antigens released by infections during pregnancy can stimulate an immune response or induce immunoregulatory networks in the fetus affecting susceptibility to infection and disease later in life. How antigen crosses from the maternal to fetal environment is poorly understood. One hypothesis is that transplacental antigen transfer occurs as immune complexes, via receptor-mediated transport across the syncytiotrophoblastic membrane and endothelium of vessels in fetal villi. This hypothesis has never been directly tested. Here we studied Plasmodium falciparum merozoite surface protein 1 (MSP1) that is released upon erythrocyte invasion. We found MSP1 in cord blood from a third of newborns of malaria-infected women and in >90% following treatment with acid dissociation demonstrating MSP1 immune complexes. Using an ex vivo human placental model that dually perfuses a placental cotyledon with independent maternal and fetal circuits, immune-complexed MSP1 transferred from maternal to fetal circulation. MSP1 alone or with non-immune plasma did not transfer; pre-incubation with human plasma containing anti-MSP1 was required. MSP1 bound to IgG was detected in the fetal perfusate. Laser scanning confocal microscopy demonstrated MSP1 in the fetal villous stroma, predominantly in fetal endothelial cells. MSP1 co-localized with IgG in endothelial cells, but not with placental macrophages. Thus we show, for the first time, antibody-dependent transplacental transfer of an antigen in the form of immune complexes. These studies imply frequent exposure of the fetus to certain antigens with implications for management of maternal infections during pregnancy and novel approaches to deliver vaccines or drugs to the fetus.

Functional genetic variants in DC-SIGNR are associated with mother-to-child transmission of HIV-1

Background

Mother-to-child transmission (MTCT) is the main cause of HIV-1 infection in children worldwide. Given that the C-type lectin receptor, dendritic cell-specific ICAM-grabbing non-integrin-related (DC-SIGNR, also known as CD209L or liver/lymph node–specific ICAM-grabbing non-integrin (L-SIGN)), can interact with pathogens including HIV-1 and is expressed at the maternal-fetal interface, we hypothesized that it could influence MTCT of HIV-1.

Methods and Findings

To investigate the potential role of DC-SIGNR in MTCT of HIV-1, we carried out a genetic association study of DC-SIGNR in a well-characterized cohort of 197 HIV-infected mothers and their infants recruited in Harare, Zimbabwe. Infants harbouring two copies of DC-SIGNR H1 and/or H3 haplotypes (H1-H1, H1-H3, H3-H3) had a 3.6-fold increased risk of in utero (IU) (P = 0.013) HIV-1 infection and a 5.7-fold increased risk of intrapartum (IP) (P = 0.025) HIV-1 infection after adjusting for a number of maternal factors. The implicated H1 and H3 haplotypes share two single nucleotide polymorphisms (SNPs) in promoter region (p-198A) and intron 2 (int2-180A) that were associated with increased risk of both IU (P = 0.045 and P = 0.003, respectively) and IP (P = 0.025, for int2-180A) HIV-1 infection. The promoter variant reduced transcriptional activity in vitro. In homozygous H1 infants bearing both the p-198A and int2-180A mutations, we observed a 4-fold decrease in the level of placental DC-SIGNR transcripts, disproportionately affecting the expression of membrane-bound isoforms compared to infant noncarriers (P = 0.011).

Conclusion

These results suggest that DC-SIGNR plays a crucial role in MTCT of HIV-1 and that impaired placental DC-SIGNR expression increases risk of transmission.

Maternal-fetal DNA admixture is associated with intrapartum mother-to-child transmission of HIV-1 in Blantyre, Malawi

BACKGROUND

The mechanism of mother-to-child transmission (MTCT) of HIV-1 is not well described.

METHODS

Of 328 HIV-infected mother-infant pairs, we identified 91 that had discordant angiotensin I-converting enzyme and glutathione S-transferase M1 alleles. Maternal alleles in cord blood were quantified with real-time polymerase chain reaction, as indicators of microtransfusions.

RESULTS

HIV-1 infected infants had more maternal DNA in cord blood than their uninfected counterparts. Increased maternal DNA in cord blood was associated with preterm delivery, low birth weight, and maternal immunosuppression.

CONCLUSION

Intrapartum MTCT was associated with placental microtransfusions. The associations among placental microtransfusion, in-utero MTCT, maternal immunosuppression, and poor birth outcome should be further investigated.

The molecular epidemiology of HIV-1 envelope diversity during HIV-1 subtype C vertical transmission in Malawian mother-infant pairs

OBJECTIVES

To study the relationship between HIV-1 subtype C genetic diversity and mother-to-child transmission and to determine if transmission of HIV-1 V1/V2 env variants occurs stochastically.

DESIGN

Case-case-control study of Malawian mother-infant pairs consisting of 32 nontransmitting women, 25 intrauterine transmitters, and 23 intrapartum transmitters in Blantyre, Malawi.

METHODS

A heteroduplex tracking assay against the highly variable HIV-1 env V1/V2 region was used to characterize the relationship between HIV-1 diversity and mother-to-child transmission. The relative abundance of the maternal env variants was quantified and categorized as transmitted or nontransmitted based on the env variants detected in the infant plasma. The V1/V2 region was sequenced from two mother-infant pairs and a phylogenetic tree was built.

RESULTS

No relationship was found between transmission and overall maternal env diversity. Infants had less diverse HIV-1 populations than their mothers, and intrauterine-infected infants had fewer V1/V2 variants and were more likely to harbor a homogeneous V1/V2 population than infants infected intrapartum. V1/V2 sequences cloned from two mother-infant transmission pairs support multiple env variant transmission when multiple variants are detected, rather than single variant transmission followed by diversification. Almost 50% of the HIV-infected infants contained V1/V2 env variants that were not detected in maternal plasma samples. Finally transmission of env variants was not related to their abundance in maternal blood.

CONCLUSION

These data suggest that the predominant mechanism(s) of HIV-1 subtype C mother-to-child transmission differs by the timing of transmission and is unlikely to be explained by a simple stochastic model.

CCR5 haplotypes and mother-to-child HIV transmission in Malawi

Background

CCR5 and CCR2 gene polymorphisms (SNPs) have been associated with protection against HIV transmission in adults and with delayed progression to AIDS. The CCR5 Δ32 deletion and SNP -2459G are associated with reduced expression of the CCR5 protein.

Methodology/Principal Findings

We investigated the association between infant CCR2/CCR5 diplotype and HIV mother to child transmission (MTCT) in Malawi. Blood samples from infants (n = 552) of HIV positive women who received nevirapine were genotyped using a post-PCR multiplex ligase detection reaction and haplotypes were identified based on 8 CCR2/CCR5 SNPs and the open reading frame 32 base pair deletion. Following verification of Hardy-Weinberg equilibrium, log linear regression was performed to examine the association between mutations and MTCT. Overall, protection against MTCT was weakly associated with two CCR5 SNPs, -2459G (Risk ratio [RR], 0.78; confidence interval [CI], 0.54–1.12), and the linked CCR5 -2135T (RR, 0.78; CI, 0.54–1.13). No child carried the CCR5 Δ32 SNP. Maternal Viral Load (MVL) was found to be an effect measure modifier. Among mothers with low MVL, statistically significant protection against MTCT was observed for -2459G (RR, 0.50; CI, 0.27–0.91), and -2135T (RR, 0.51; CI, 0.28–0.92). Statistically significant protection was not found at high MVL.

Conclusions/Significance

Results from this study suggest that CCR5 SNPs -2459G and -2135T associated with reduced receptor expression protect against MTCT of HIV at low MVLs, whereas high MVLs may over-ride differences in coreceptor availability.

Intrapartum transmission after mucosal exposure to HIV was not observed with single-dose nevirapine for mother and child

BACKGROUND

Intrapartum transmission of HIV has been reported to be associated with HIV in oropharyngeal secretions (OPSs) of the child. In this study, we analyze the frequency of intrapartum transmission after mucosal exposure to HIV after administration of single-dose nevirapine.

METHODS

Eighty mothers and their children participating in a prevention of mother-to-child transmission of HIV program in Uganda who took a single dose of nevirapine according to the HIVNET012 protocol participated in the study. HIV-1 was quantified by polymerase chain reaction (PCR) in the mothers' and children's plasma, in cervicovaginal secretions (CVSs), and in the children's OPSs. Intrapartum transmission was defined as a positive HIV-1 RNA PCR result at week 1 or 2 after birth and a previously negative PCR result.

RESULTS

Ninety-seven percent of children had detectable nevirapine in their OPS (median = 592 ng/mL). Fifty-seven (81%) children had HIV-negative OPSs, and 13 (19%) had HIV-positive OPSs. All children of mothers with HIV-negative CVSs had HIV-negative OPSs. HIV-1 levels of OPSs and CVSs correlated (r = 0.33, P = 0.027). None of the babies with detectable HIV-1 in the OPSs became infected by means of intrapartum transmission.

CONCLUSION

Intrapartum HIV infection was not observed after mucosal exposure to HIV-1 after administration of a single dose of nevirapine to the mother and child.

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.