Placental Inflammation and Perinatal Transmission of HIV-1:

Disturbances in the IgG Antibody Profile in HIV-Exposed Uninfected Infants Associated with Maternal Factors

Over the last 20 years, the incidence of vertical HIV transmission has decreased from 25%-42% to less than 1%. Although there are no signs of infection, the health of HIV-exposed uninfected (HEU) infants is notoriously affected during the first months of life, with opportunistic infections being the most common disease. Some studies have reported effects on the vertical transfer of antibodies, but little is known about the subclass distribution of these antibodies. We proposed to evaluate the total IgG concentration and its subclasses in HIV+ mothers and HEU pairs and to determine which maternal factors condition their levels. In this study, plasma from 69 HEU newborns, their mothers, and 71 control pairs was quantified via immunoassays for each IgG isotype. Furthermore, we followed the antibody profile of HEUs throughout the first year of life. We showed that mothers present an antibody profile characterized by high concentrations of IgG1 and IgG3 but reduced IgG2, and HEU infants are born with an IgG subclass profile similar to that of their maternal pair. Interestingly, this passively transferred profile could remain influenced even during their own antibody production in HEU infants, depending on maternal conditions such as CD4+ T-cell counts and maternal antiretroviral treatment. Our findings indicate that HEU infants exhibit an altered IgG subclass profile influenced by maternal factors, potentially contributing to their increased susceptibility to infections.

Gestational Viral Infections: Role of Host Immune System

Viral infections in pregnancy are major causes of maternal and fetal morbidity and mortality. Infections can develop in the neonate transplacentally, perinatally, or postnatally (from breast milk or other sources) and lead to different clinical manifestations, depending on the viral agent and the gestational age at exposure. Viewing the peculiar tolerogenic status which characterizes pregnancy, viruses could exploit this peculiar immunological status to spread or affect the maternal immune system, adopting several evasion strategies. In fact, both DNA and RNA virus might have a deep impact on both innate and acquired immune systems. For this reason, investigating the interaction with these pathogens and the host's immune system during pregnancy is crucial not only for the development of most effective therapies and diagnosis but mostly for prevention. In this review, we will analyze some of the most important DNA and RNA viruses related to gestational infections.

Children who are HIV-exposed and uninfected: evidence for action

Prior to widespread availability of antiretroviral therapy (ART) in sub-Saharan Africa, children who were HIV-exposed but uninfected (HEU) had increased mortality, morbidity and undernutrition compared with children who were HIV-unexposed. Scale-up of ART has led to impressive declines in vertical HIV transmission, but over 15 million children are now HEU, 90% of whom live in sub-Saharan Africa. There are ongoing health disparities among children who are HEU, with higher mortality, morbidity and stunting and modest impairments in early child development, which collectively hamper health and human capital in high prevalence countries. The underlying causes are multifactorial and include exposure to HIV, co-infections and a skewed antenatal inflammatory milieu, particularly if mothers start ART once they have advanced disease, as well as socioeconomic risk factors, which may cluster in HIV-affected households. Improving maternal health through early and sustained ART, ensuring optimal breastfeeding, and implementing evidence-based priority interventions for all children in areas of high HIV prevalence, will likely improve outcomes. A more comprehensive intervention package based on the Nurturing Care Framework may have particular benefits for children who are HEU, to close health gaps and ensure that the next generation of HIV-free children survive and thrive, and lead healthy and productive lives.

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.

Placental pathology in women with HIV

Recognizing the importance of placental features and their unique functions can provide insight into maternal health, the uterine environment during the course of pregnancy, birth outcomes and neonatal health. In the context of HIV and antiretroviral therapy (ART), there have been great strides in the prevention of mother to child transmission of HIV. However, there is still paucity of data on the impact of HIV/ART exposure on placental pathology and studies available only examine specific patterns of placental injury, further justifying the need for a more defined and comprehensive approach to the differential diagnoses of HIV/ART-exposed placentae. The purpose of this review is to consolidate findings from individual studies that have been reported on patterns of placental injury in the context of HIV/ART exposure. In both the pre- and post-ART eras HIV and/or ART has been associated with placental injury including maternal vascular malperfusion as well as acute and chronic inflammation. These patterns of injury are further associated with adverse birth outcomes including preterm birth and current evidence suggests an association between poor placental function and compromised fetal development. With the ever increasing number of pregnant women with HIV on ART, there is a compelling need for full incorporation of placental diagnoses into obstetric disease classification. It is also important to take into account key elements of maternal clinical history. Lastly, there is a need to standardize the reporting of placental pathology in order to glean additional insight into the elucidation of HIV/ART associated placental injury.

T cell Homeostatic Imbalance in Placentae from Women with HIV in the absence of Vertical Transmission

BACKGROUND

Implementation of universal antiretroviral therapy (ART) has significantly lowered vertical transmission rates but has also increased numbers of HIV-exposed uninfected children (HEU), who remain vulnerable to morbidities. Here, we investigated whether T cell alterations in the placenta contribute to altered immune status in HEU.

METHODS

We analyzed T cells from term placentae decidua and villous tissue and paired cord blood from pregnant women with HIV (PWH) who initiated ART late in pregnancy (n=21) with pregnant women not living with HIV (PWNH) (n=9).

RESULTS

Placentae from PWH showed inverted CD4:CD8 ratios and higher proportions of tissue resident CD8+ T cells in villous tissue relative to control placentae. CD8+ T cells in the fetal capillaries, which were of fetal origin, positively correlated with maternal plasma viraemia prior to ART initiation, implying that imbalanced T cells persisted throughout pregnancy. Additionally, the expanded memory differentiation of CD8+ T cells was confined to the fetal placental compartment and cord blood but was not observed in the maternal decidua.

CONCLUSIONS

T cell homeostatic imbalance in the blood circulation of PWH is reflected in the placenta. The placenta may be a causal link between HIV-induced maternal immune changes during gestation and altered immunity in newborn infants in the absence of vertical transmission.

Mini review: Prevention of mother-child transmission of HIV: 25 years of continuous progress toward the eradication of pediatric AIDS?

Prevention of mother-to-child transmission with antiretrovirals is extraordinarily effective. When medically well followed, a mother living with human immunodeficiency virus can now expect to avoid transmitting the virus to her child. Despite the immense difficulties inherent in the global implementation of this treatment, the virtual disappearance of pediatric AIDS can be considered in the long term.

Impact of maternal HIV infection on pregnancy outcomes in southwestern China - a hospital registry based study

Globally, human immune deficiency virus (HIV)/acquired immune deficiency syndrome (AIDS) continues to be a major public health issue. With improved survival, the number of people living with HIV/AIDS is increasing, with over 2 million among pregnant women. Investigating adverse pregnant outcomes of HIV-infected population and associated factors are of great importance to maternal and infant health. A cross-sectional data collected from hospital delivery records of 4397 mother-infant pairs in southwestern China were analysed. Adverse pregnant outcomes (including low birthweight/preterm delivery/low Apgar score) and maternal HIV status and other characteristics were measured. Two hundred thirteen (4.9%) mothers were HIV positive; maternal HIV infection, rural residence and pregnancy history were associated with all three indicators of adverse pregnancy outcomes. This research suggested that maternal population have high prevalence in HIV infection in this region. HIV-infected women had higher risks of experiencing adverse pregnancy outcomes. Rural residence predisposes adverse pregnancy outcomes. Findings of this study suggest social and medical support for maternal-infant care needed in this region, selectively towards rural areas and HIV-positive mothers.

Placental Structure in Preterm Birth Among HIV-Positive Versus HIV-Negative Women in Kenya

Background:

Preterm birth (PTB) is a major cause of infant morbidity and mortality in developing countries. Recent data suggest that in addition to Human Immunodeficiency Virus (HIV) infection, use of antiretroviral therapy (ART) increases the risk of PTB. As the mechanisms remain unexplored, we conducted this study to determine whether HIV and ART were associated with placental changes that could contribute to PTB.

Setting:

We collected and evaluated placentas from 38 HIV-positive women on ART and 43 HIV-negative women who had preterm deliveries in Nairobi, Kenya.

Methods:

Anatomical features of the placentas were examined at gross and microscopic levels. Cases were matched for gestational age and compared by the investigators who were blinded to maternal HIV serostatus.

Results:

Among preterm placentas, HIV infection was significantly associated with thrombosis (P = 0.001), infarction (P = 0.032), anomalies in cord insertion (P = 0.02), gross evidence of membrane infection (P = 0.043), and reduced placental thickness (P = 0.010). Overall, preterm placentas in both groups were associated with immature villi, syncytial knotting, villitis, and deciduitis. Features of HIV-positive versus HIV-negative placentas included significant fibrinoid deposition with villus degeneration, syncytiotrophoblast delamination, red blood cell adhesion, hypervascularity, and reduction in both surface area and perimeter of the terminal villi.

Conclusions:

These results imply that HIV infection and/or ART are associated with morphological changes in preterm placentas that contribute to delivery before 37 weeks. Hypervascularity suggests that the observed pathologies may be attributable, in part, to hypoxia. Further research to explore potential mechanisms will help elucidate the pathways that are involved perhaps pointing to interventions for decreasing the risk of prematurity among HIV-positive women.

Minimizing the Risk of Perinatal Human Immunodeficiency Virus Transmission

Importance

There are approximately 284,500 adolescent and adult women living with human immunodeficiency virus (HIV) in the United States. It is estimated that approximately 8500 of these women give birth annually. While the rate of perinatal transmission in the United States has decreased by more than 90% since the early 1990s, potentially preventable HIV transmission events still occur and cause significant morbidity and mortality.

Objective

The aim of this review was to summarize the current data regarding perinatal HIV transmission timing and risk factors, current management recommendations, and implications of timing of transmission on patient management.

Evidence Acquisition

Literature review.

Results

This review reiterates that the risk of perinatal HIV transmission can be reduced to very low levels by following current recommendations for screening for HIV in all pregnant women and properly treating HIV-infected mothers, as well as using evidence-based labor management practices.

Conclusions and Relevance

Familiarity with the pathogenesis of HIV transmission is important for obstetric care providers to appropriately manage HIV-infected women in pregnancy, intrapartum, and the postpartum period.

Combined evaluation of sexually transmitted infections in HIV-infected pregnant women and infant HIV transmission

Background

Sexually transmitted infections (STIs) including Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG), Treponema pallidum (TP), and cytomegalovirus (CMV) may lead to adverse pregnancy and infant outcomes. The role of combined maternal STIs in HIV mother-to-child transmission (MTCT) was evaluated in mother-infant pairs from NICHD HPTN 040.

Methodology

Urine samples from HIV-infected pregnant women during labor were tested by polymerase chain reaction (PCR) for CT, NG, and CMV. Infant HIV infection was determined by serial HIV DNA PCR testing. Maternal syphilis was tested by VDRL and confirmatory treponemal antibodies.

Results

A total of 899 mother-infant pairs were evaluated. Over 30% had at least one of the following infections (TP, CT, NG, and/or CMV) detected at the time of delivery. High rates of TP (8.7%), CT (17.8%), NG (4%), and CMV (6.3%) were observed. HIV MTCT was 9.1% (n = 82 infants). HIV MTCT was 12.5%, 10.3%, 11.1%, and 26.3% among infants born to women with CT, TP, NG or CMV respectively. Forty-two percent of HIV-infected infants were born to women with at least one of these 4 infections. Women with these infections were nearly twice as likely to have an HIV-infected infant (aOR 1.9, 95% CI 1.1–3.0), particularly those with 2 STIs (aOR 3.4, 95% CI 1.5–7.7). Individually, maternal CMV (aOR 4.4 1.5–13.0) and infant congenital CMV (OR 4.1, 95% CI 2.2–7.8) but not other STIs (TP, CT, or NG) were associated with an increased risk of HIV MTCT.

Conclusion

HIV-infected pregnant women identified during labor are at high risk for STIs. Co-infection with STIs including CMV nearly doubles HIV MTCT risk. CMV infection appears to confer the largest risk of HIV MTCT.

Trial registration

NCT00099359.

Maternal HIV infection alters the immune balance in the mother and fetus; implications for pregnancy outcome and infant health

PURPOSE OF REVIEW

With the rapid roll-out of combination antiretroviral therapy to prevent mother-to-child transmission of HIV, there is an annual increase in the number of uninfected infants born to HIV-infected women. Although the introduction of combination antiretroviral therapy has vastly improved pregnancy outcome and the health of infants born to HIV-infected women, concerns remain regarding the impact the maternal HIV infection on the pregnancy outcome and the health of HIV-exposed uninfected infants.

RECENT FINDINGS

Maternal HIV infection is associated with negative pregnancy outcomes such as low birth weight. In addition, an increased susceptibility to infections is reported in HIV-exposed uninfected infants compared with infants born to uninfected women. Studies have shown that HIV-exposure affects the maternal/fetal unit, with increase of proinflammatory cytokine produced by placental cells, as well as altered infant immune responses. These changes could provide the underlying conditions for negative pregnancy outcomes and facilitate mother-to-child transmission of HIV in the infant. Further studies are required to understand the underlying mechanisms and investigate whether these altered infant immune responses persist and have clinical consequences beyond childhood.

SUMMARY

HIV infection in pregnant women is associated with altered immune responses in HIV-infected women and their offspring with clinical consequences for pregnancy outcome and the HIV-exposed uninfected infant. Further studies are required to address the origin and long-term consequences of prenatal HIV-exposure and subsequent immune activation for infant health.

The Immune System of HIV-Exposed Uninfected Infants

Infants born to human immunodeficiency virus (HIV) infected women are HIV-exposed but the majority remains uninfected [i.e., HIV-exposed uninfected (HEU)]. HEU infants suffer greater morbidity and mortality from infections compared to HIV-unexposed (HU) peers. The reason(s) for these worse outcomes are uncertain, but could be related to an altered immune system state. This review comprehensively summarizes the current literature investigating the adaptive and innate immune system of HEU infants. HEU infants have altered cell-mediated immunity, including impaired T-cell maturation with documented hypo- as well as hyper-responsiveness to T-cell activation. And although prevaccination vaccine-specific antibody levels are often lower in HEU than HU, most HEU infants mount adequate humoral immune response following primary vaccination with diphtheria toxoid, haemophilus influenzae type b, whole cell pertussis, measles, hepatitis B, tetanus toxoid, and pneumococcal conjugate vaccines. However, HEU infants are often found to have lower absolute neutrophil counts as compared to HU infants. On the other hand, an increase of innate immune cytokine production and expression of co-stimulatory markers has been noted in HEU infants, but this increase appears to be restricted to the first few weeks of life. The immune system of HEU children beyond infancy remains largely unexplored.

Chlamydia and Gonorrhea in HIV-Infected Pregnant Women and Infant HIV Transmission

BACKGROUND

Sexually transmitted infections (STIs) such as Chlamydia trachomatis (CT) and Neisseria gonorrhoeae (NG) can lead to adverse pregnancy and neonatal outcomes. The prevalence of STIs and its association with HIV mother-to-child transmission (MTCT) were evaluated in a substudy analysis from a randomized, multicenter clinical trial.

METHODOLOGY

Urine samples from HIV-infected pregnant women collected at the time of labor and delivery were tested using polymerase chain reaction testing for the detection of CT and NG (Xpert CT/NG; Cepheid, Sunnyvale, CA). Infant HIV infection was determined by HIV DNA polymerase chain reaction at 3 months.

RESULTS

Of the 1373 urine specimens, 249 (18.1%) were positive for CT and 63 (4.6%) for NG; 35 (2.5%) had both CT and NG detected. Among 117 cases of HIV MTCT (8.5% transmission), the lowest transmission rate occurred among infants born to CT- and NG-uninfected mothers (8.1%) as compared with those infected with only CT (10.7%) and both CT and NG (14.3%; P = 0.04). Infants born to CT-infected mothers had almost a 1.5-fold increased risk for HIV acquisition (odds ratio, 1.47; 95% confidence interval, 0.9-2.3; P = 0.09).

CONCLUSIONS

This cohort of HIV-infected pregnant women is at high risk for infection with CT and NG. Analysis suggests that STIs may predispose to an increased HIV MTCT risk in this high-risk cohort of HIV-infected women.

Impact of HIV-1 infection on the feto-maternal crosstalk and consequences for pregnancy outcome and infant health

Adaptation of the maternal immune system to establish maternal/fetal equilibrium is required for a successful pregnancy. Viral infections, including HIV-1 infection, can alter this maternal/fetal equilibrium, with significant consequences for pregnancy outcome, including miscarriages, impaired fetal growth, and premature delivery. Furthermore, maternal HIV-1 infection has been shown to have a long-term impact on the developing fetal immune system also when the infant is not infected with the virus. In this review, we discuss the consequences of maternal HIV-1 infection and antiretroviral therapy on pregnancy outcome and the health of the uninfected HIV-1-exposed infant.

Chlamydia trachomatis Infection in Pregnancy: The Global Challenge of Preventing Adverse Pregnancy and Infant Outcomes in Sub-Saharan Africa and Asia

Screening and treatment of sexually transmitted infections (STIs) in pregnancy represents an overlooked opportunity to improve the health outcomes of women and infants worldwide. Although Chlamydia trachomatis is the most common treatable bacterial STI, few countries have routine pregnancy screening and treatment programs. We reviewed the current literature surrounding Chlamydia trachomatis in pregnancy, particularly focusing on countries in sub-Saharan Africa and Asia. We discuss possible chlamydial adverse pregnancy and infant health outcomes (miscarriage, stillbirth, ectopic pregnancy, preterm birth, neonatal conjunctivitis, neonatal pneumonia, and other potential effects including HIV perinatal transmission) and review studies of chlamydial screening and treatment in pregnancy, while simultaneously highlighting research from resource-limited countries in sub-Saharan Africa and Asia.

Strategies for the prevention of mother to child transmission in Western countries: an update

BACKGROUND

During the last decades remarkable scientific advances have been made toward the prevention of HIV mother-to-child transmission, in particular in developed nations. The aim of this review was to analyze the latest findings and available international recommendations on the prevention of HIV mother-to-child transmission in high-income countries.

METHODS

We performed a literature search of the Cochrane Library, MEDLINE by PubMed and EMBASE from database inception through June 2014, using the following terms: HIV, mother-to-child transmission and mother-to-child-transmission prevention. All types of articles in the English language were included. US and available European guidelines were searched and included in the analysis.

RESULTS

One hundred fifty articles were selected for inclusion in this review.

CONCLUSIONS

Global epidemiology of HIV infection is rapidly evolving, in particular in high-resource countries. The interpretation of clinical and epidemiological studies is crucial for the development of evidence-based recommendations to guide the management of HIV mother-to-child transmission. Although significant progress has been made, heterogeneity between countries in specific interventions still exists, which may address future research.

Chorioamnionitis in pregnancy: a comparative study of HIV-positive and HIV-negative parturients

Chorioamnionitis is an important risk factor for vertical transmission of HIV/AIDS. We compared the prevalence and correlates of histologic chorioamnionitis (HCA) in HIV-positive and HIV-negative pregnant women. HIV-positive and -negative parturients were interviewed, examined and had their placentas examined histologically for chorioamnionitis. Data regarding HIV were also retrieved from their hospital records. A total of 298 parturients (150 HIV positive and 148 HIV negative) were enrolled. The two groups were similar in socio-demographic and obstetric parameters except for age. The prevalence of HCA was 57.1% in HIV-positive women and 61.6% in HIV-negative women (p = 0.43). HCA staging was associated with the number of intrapartum vaginal examinations in HIV-positive subjects and nulliparity in HIV-negative subjects. The number of intrapartum vaginal examinations and coitus in the week prior to delivery significantly affected the grade of HCA in HIV-negative subjects. The prevalence of HCA in both HIV-positive and HIV-negative is high. Most variables did not affect the occurrence of HCA in both groups studied except number of intrapartum examinations, coitus in the preceding one week and nulliparity, which were related to severity of the disease.

HIV transmission to extremely low birth weight infants

BACKGROUND

Prematurity increases the perinatal HIV transmission rate compared with term infants. There is sparse literature documenting the risk of transmission of HIV to extremely low birth weight (ELBW) infants.

OBJECTIVE

To determine the risk of perinatal transmission of HIV to ELBW infants in a tertiary neonatal unit in South Africa.

METHODS

A prospective database was maintained on all inborn ELBW infants over a 1-year period from March 2010 to February 2011. Survival and DNA HIV polymerase chain reaction results at 6 weeks were recorded.

RESULTS

Of the 180 ELBW infants, 51 (28%) of these babies were HIV exposed. Of these 51 infants, 37 survived until 6 weeks of age. Polymerase chain reaction testing revealed 1 HIV-positive infant for a rate of 2.7% (95% confidence interval: 0.7-14.1%). Twenty-six (72%) of the 36 mothers received antiretroviral drugs, but only 16 (44%) had been treated for more than 1 month.

CONCLUSIONS

The rate of HIV transmission in this cohort of ELBW infants is very low despite only 44% of the mothers receiving adequate antiretroviral drugs. We postulate that this is due to our high (89%) cesarean section rate, universal (100%) infant prophylactic antiretroviral drugs and the use of pasteurized breast milk.

Morphologic changes in the placentas of HIV-positive women and their association with degree of immune suppression

OBJECTIVE

To provide baseline information regarding a possible association between specific histopathologic features of the placentas of HIV-positive women and the degree of immune suppression.

METHODS

A prospective single-blinded laboratory-based pilot study was conducted at Tygerberg Hospital, South Africa. The macroscopic and microscopic features of placentas from HIV-positive (n=91) and HIV-negative women (n=89) were compared and recorded using a standard template. Investigators were blinded to the participants' HIV status and CD4-positive cell count.

RESULTS

Placentas from the HIV-positive group were characterized by decreased weight and increased number of marginal infarcts relative to the HIV-negative group. The most important microscopic finding was the increased presence of villitis of unknown etiology (VUE) among the group of untreated HIV-positive women with CD4 cell counts of 200 cells/mm(3) or below.

CONCLUSION

Both macroscopic and microscopic differences relating to the degree of immune suppression were identified, which seemingly contradicts previous reports. Larger studies are warranted to define the function of antiretroviral therapy and VUE in the mechanism of mother-to-fetus transmission of HIV. Furthermore, the potential role of VUE in the pathophysiology of the compromised immune response observed among HIV-exposed but uninfected infants should be investigated.

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.

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.

Placental malaria and mother-to-child transmission of human immunodeficiency virus-1 in rural Rwanda

We conducted a nested case-control study of placental malaria (PM) and mother-to-child transmission (MTCT) of human immunodeficiency virus-1 (HIV-1) within a prospective cohort of 627 mother-infant pairs followed from October 1989 until April 1994 in rural Rwanda. Sixty stored placentas were examined for PM and other placental pathology, comparing 20 HIV-infected mother-infant (perinatal transmitter) pairs, 20 HIV-uninfected pairs, and 20 HIV-infected mothers who did not transmit to their infant perinatally. Of 60 placentas examined, 45% showed evidence of PM. Placental malaria was associated with increased risk of MTCT of HIV-1 (adjusted odds ratio [aOR] = 6.3; 95% confidence interval [CI] = 1.4-29.1), especially among primigravidae (aOR = 12.0; 95% CI = 1.0-150; P < 0.05). Before antiretroviral therapy or prophylaxis, PM was associated with early infant HIV infection among rural Rwandan women living in a hyper-endemic malaria region. Primigravidae, among whom malaria tends to be most severe, may be at higher risk.

Infectious disease immunohistochemistry in placentas from HIV-positive and HIV-negative patients

Studies comparing placental pathology between human immunodeficiency virus (HIV)-positive and HIV-negative patients have shown conflicting results. In addition, few studies have evaluated the infectious etiology of placental inflammation in HIV-positive patients. We examined a cohort of placentas from 73 HIV-positive and 41 HIV-negative patients to gain a better understanding of the spectrum of placental inflammatory lesions. Bacterial and viral immunohistochemistry (IHC) was run on a subset of placentas (12 HIV-positive and 7 HIV-negative) with the greatest amount of inflammation. Although few histologic differences were seen between the HIV-positive and HIV-negative groups, chorioamnionitis was of a higher stage in the HIV-positive placentas. An infectious agent was found by IHC in 3 of 7 HIV-negative patients (2 Neisseria spp. and 1 group B Streptococcus ). One HIV-positive placenta showed gram-positive cocci on fetal membranes; organisms were not detected by IHC. In 2 patients, the etiologic agent was not suspected prior to IHC. This study identified that acute inflammation is less common in placentas from HIV-positive patients, compared with HIV-negative patients. However, when severe inflammation is present, infectious organisms may be identified by IHC, providing a more specific diagnosis and offering a beneficial impact in maternal and fetal management.

Sensitive oligonucleotide ligation assay for low-level detection of nevirapine resistance mutations in human immunodeficiency virus type 1 quasispecies

This study has adapted the oligonucleotide ligation assay (OLA) to probe for low-level nevirapine (NVP) resistance mutations K103N and Y181C in the human immunodeficiency virus type 1 (HIV-1) population of infected mother-infant pairs from Uganda. When NVP is used to prevent perinatal transmission, NVP-resistant HIV-1 clones may be rapidly selected due to a low barrier for mutation and a relatively high level of fitness (compared to that of other drug-resistant HIV-1 clones). Monitoring for even a low frequency of NVP resistance mutations may help predict the success of subsequent treatment or warrant the use of another regimen to prevent transmission in a subsequent pregnancy. The standard OLA was optimized by using nonstandard bases in oligonucleotides to allow promiscuous base pairing and accommodate significant HIV-1 heterogeneity. Radiolabeled as opposed to fluorescently tagged oligonucleotides increased the sensitivity, whereas alteration of the template, oligonucleotides, salt, and thermostable DNA ligase concentrations increased the specificity for the detection of minority codons. This modified OLA is now capable of detecting mutants with the K103N or the Y181C mutation present in an HIV-1 population at a frequency of approximately 0.4% and is at least 10- to 30-fold more sensitive than the original protocol. A cohort of 19 Ugandan mothers who received NVP treatment perinatally were sampled 6 weeks postdelivery. Ten of 19 HIV-1 DNA samples extracted from peripheral blood mononuclear cells had a detectable K103N (0.5 to 44%) or Y181C (0.8 to 92.5%) mutation, but only one plasma HIV-1 RNA sample had a viral population with the Y181C mutation. These findings suggest that OLA is a robust, sensitive, and specific method for the detection of low-frequency drug resistance mutations in an intrapatient HIV-1 population.

A phase III clinical trial of antibiotics to reduce chorioamnionitis-related perinatal HIV-1 transmission

OBJECTIVE

A multisite study was conducted in Africa to assess the efficacy of antibiotics to reduce mother-to-child transmission (MTCT) of HIV-1.

DESIGN

A randomized, double-blinded, placebo-controlled, phase III clinical trial.

METHODS

HIV-1-infected women were randomly assigned at 20-24 weeks' gestation to receive either antibiotics (metronidazole plus erythromycin antenatally and metronidazole plus ampicillin intrapartum) or placebo. Maternal study procedures were performed at 20-24, 26-30, and 36 weeks antenatally, and at labor/delivery. Infants were seen at birth, 4-6 weeks, and 3, 6, 9 and 12 months. The primary efficacy endpoints were overall infant HIV-1 infection and HIV-1-free survival at 4-6 weeks. All women and infants received single-dose nevirapine prophylaxis in this study.

RESULTS

A total of 1510 live-born infants were included in the primary analysis. The proportions of HIV-1-infected infants at birth were similar (antibiotics 7.1%; placebo 8.3%; P = 0.41). Likewise, there were no statistically significant differences at 4-6 weeks in the overall risk of MTCT of HIV-1 (antibiotics 16.2%; placebo 15.8%; P = 0.89) or HIV-1-free survival (79.4% in each study arm). Post-randomization, the proportion of women with bacterial vaginosis at the second antenatal visit was significantly lower in the antibiotics arm compared with the placebo arm (23.8 versus 39.7%; P < 0.001), but the frequency of histological chorioamnionitis was not different (antibiotics 36.9%; placebo 39.7%; P = 0.30). Adverse events in mothers and their infants did not differ by randomization arm.

CONCLUSION

This simple antepartum and peripartum antibiotic regimen did not reduce the risk of MTCT of HIV-1.

Increased Risk of Intrauterine Transmission of HIV-1 Associated With Granulocyte Elastase in Endocervical Mucus

BACKGROUND

One of the remaining challenges in the prevention of mother-to-child transmission of HIV is to reduce the risk of the transmission during pregnancy. It remains to be investigated which factors affect intrauterine HIV transmission and how they can be identified and addressed during pregnancy.

METHODS

Granulocyte elastase in the endocervical mucus of HIV-positive pregnant women in Zambia was measured, and its association with intrauterine transmission of HIV-1 from the mother to the fetus was investigated.

RESULTS

The intrauterine transmission rate determined by polymerase chain reaction assay of DNA from neonates at birth was 15.3%. The risk for intrauterine transmission was 8.65-fold higher in women who were positive for granulocyte elastase than in those who were negative.

CONCLUSION

We suggest that the women showing positive granulocyte elastase at delivery be strongly suspected of having and if having had chorioamnionitis during pregnancy, which could affect the intrauterine transmission of HIV.

Acute and chronic chorioamnionitis and the risk of perinatal human immunodeficiency virus-1 transmission

OBJECTIVE

This study was undertaken to examine the prevalence of acute and chronic chorioamnionitis among women infected with human immunodeficiency virus-1 (HIV-1) and to determine the relative contribution of each to perinatal HIV-1 transmission.

STUDY DESIGN

In 227 HIV-infected women receiving intrapartum/neonatal nevirapine prophylaxis, we examined associations between fetal membrane histology, cord blood interleukin-6 (IL-6), and perinatal HIV-1 transmission.

RESULTS

Acute chorioamnionitis was present in 122 of 227 specimens; chronic chorioamnionitis in 64 of 227. There was a positive correlation between acute chorioamnionitis and labor length (r = 0.208; P = .002), time of ruptured membrane (r = 0.177; P = .008), and cord IL-6 (r = 0.390; P < .001). Chronic chorioamnionitis was associated with high viral load (P = .05) and low cord IL-6 (P < .001). Severe chronic chorioamnionitis was associated with intrauterine HIV-1 transmission (odds ratio [OR] = 7.61; 95% CI = 1.04-85.5), but no correlation was demonstrated between acute chorioamnionitis and vertical transmission.

CONCLUSION

In a setting of high perinatal nevirapine use, acute chorioamnionitis was not associated with vertical HIV-1 transmission. Risk for intrauterine transmission increased significantly when chronic chorioamnionitis was present.

Chorioamnionitis is associated with placental transmission of human immunodeficiency virus-1 subtype E in the early gestational period

The frequency and the cellular basis for HIV-1 transmission from mother to child in the early gestational period are poorly understood. We compared the placentas of 24 women seropositive for HIV-1 subtype E and who had not received any antiretroviral drugs, to placentas of 25 seronegative women. All placentas were obtained during therapeutic abortion at 6-23 weeks gestation. Placentas and fetal organs were examined by routine light microscopy, immunostaining for p24 capsid protein, and in situ PCR to localize which cells were infected with HIV-1 subtype E. The number of previous abortions was not a factor in placental HIV infection since this number was higher in seronegative women (P < 0.01). There were no significant differences between the placentas of the two groups with respect to presence of chorioamnionitis, villitis, villous stromal fibrosis, infarction, abnormal villous maturation, deciduitis or decidual necrosis. HIV-1 subtype E was detected in up to 83% of placentas, either by immunostaining or in situ PCR, in trophoblast, villous stromal cells, Hofbauer cells, decidual and decidual glandular epithelium. Fetal organs were positive for HIV in 30% (6/20) of cases. There was a significant association between transmission of HIV to the fetus and the histologic findings of chorioamnionitis, plasmacellular deciduitis and decidual cell necrosis. This is the first report showing an association of chorioamnionitis with early in utero transmission of HIV-1 subtype E. This may help explain the cases of in utero transmission that persist despite antiretroviral prophylaxis, given that therapy is started in the late gestational period.

[For a better understanding of the mechanisms involved in vertical transmission of HIV]

Maternal-infant transmission of human immunodeficiency virus-1 (HIV) is the primary cause of this retrovirus infection in neonates. The mechanisms of vertical transmission of HIV, in particular in utero transmission, remain poorly defined. Trophoblastic cells from the placenta are thought to be a target of HIV infection and/or may be utilized by the virus to be transported across the placental barrier by a process known as transcytosis. The vertical transmission of HIV (via infection or transcytosis) may be either favoured or inhibited by factors related to both the viral phenotype and the cellular environment.

Mother to Child Transmission of HIV

Transmission of HIV from mother to child remains a global priority, despite the fact that highly active antiretroviral therapy has dramatically reduced the number of infants born HIV-infected in the Western world. A significant number of children worldwide continue to become infected with the virus daily. Studies examining several modified therapies during pregnancy and labor have shown a considerable reduction in the transmission rate. Beyond drug therapy, factors such as viral load, maternal disease, cesarean deliveries, and placental infection also play important roles in transmission. Breastfeeding continues to be a large source of transmission to infants in less developed countries. New studies are examining components in breast milk and drug therapy in an attempt to prevent maternal-child transmission.