Association of recent HIV infection and in-utero HIV-1 transmission

Incident HIV acquisition among pregnant women in Botswana: findings from the Tsepamo birth outcomes surveillance study

INTRODUCTION

In Botswana, where almost all pregnant women known to have HIV receive antiretroviral therapy, a large proportion of vertical HIV transmission may occur among women with incident undiagnosed HIV infection during pregnancy. Botswana guidelines recommend repeat HIV testing every 3 months in pregnancy, with at least one test in the third trimester. We evaluated the rate of repeat HIV testing, calculated HIV incidence during pregnancy and estimated missed seroconversions.

METHODS

In the Botswana Tsepamo Study, we abstracted HIV test dates and results from obstetric records of all women who delivered at maternity wards in 18 communities between 7th May 2017 and 20th August 2021. We defined seroconversion as an initial negative/indeterminate HIV test in pregnancy followed by a positive test during pregnancy/at delivery. The incidence rate (IR) of seroconversion was calculated among women with > = 2 known test dates. Missed seroconversions were estimated among women without a test in the third trimester by applying the IR to the time after the last HIV test until delivery.

RESULTS

Among 103,529 women delivering in the study period testing negative at the first test and with known conception and HIV test dates, 29,085 (28%) were tested in one trimester of pregnancy, 73,156 (71%) were tested in ≥ 2 trimesters of pregnancy and 9628 (9%) had a test in all trimesters. A total of 78,162 (75%) women had a third-trimester test. There were 223 seroconversions (2.58/1000 pregnancies, 0.26%) among those with ≥ 2 known HIV test dates, yielding an IR of 0.69/100 person-years. Among 25,289 women who did not have a test in the third trimester, we estimate approximately 58 seroconversions may have been missed during pregnancy due to a lack of repeat testing. Factors associated with seroconversion during pregnancy included younger age, less education and not being married.

CONCLUSIONS

More than two-thirds of women had repeat HIV testing in pregnancy and HIV incidence was low. However, an estimated 21% of seroconversions in pregnancy were likely missed due to a lack of re-testing. To reach the goal of zero new paediatric HIV infections, Botswana will need to intensify repeat HIV testing in the third trimester of pregnancy.

The Ontogeny and Function of Placental Macrophages

The placenta is a fetal-derived organ whose function is crucial for both maternal and fetal health. The human placenta contains a population of fetal macrophages termed Hofbauer cells. These macrophages play diverse roles, aiding in placental development, function and defence. The outer layer of the human placenta is formed by syncytiotrophoblast cells, that fuse to form the syncytium. Adhered to the syncytium at sites of damage, on the maternal side of the placenta, is a population of macrophages termed placenta associated maternal macrophages (PAMM1a). Here we discuss recent developments that have led to renewed insight into our understanding of the ontogeny, phenotype and function of placental macrophages. Finally, we discuss how the application of new technologies within placental research are helping us to further understand these cells.

HIV in pregnancy: Mother-to-child transmission, pharmacotherapy, and toxicity

An estimated 1.3 million pregnant women were living with HIV in 2018. HIV infection is associated with adverse pregnancy outcomes and all HIV-positive pregnant women, regardless of their clinical stage, should receive a combination of antiretroviral drugs to suppress maternal viral load and prevent vertical fetal infection. Although antiretroviral treatment in pregnant women has undoubtedly minimized mother-to-child transmission of HIV, several uncertainties remain. For example, while pregnancy is accompanied by changes in pharmacokinetic parameters, relevant data from clinical studies are lacking. Similarly, long-term adverse effects of exposure to antiretrovirals on fetuses have not been studied in detail. Here, we review current knowledge on HIV effects on the placenta and developing fetus, recommended antiretroviral regimens, and pharmacokinetic considerations with particular focus on placental transport. We also discuss recent advances in antiretroviral research and potential effects of antiretroviral treatment on placental/fetal development and programming.

Vertical transmission of HIV among pregnant women who initially had false-negative rapid HIV tests in four South African antenatal clinics

INTRODUCTION

There is a risk of mother-to-child transmission of HIV (MTCT) during pregnancy and breastfeeding. The aim of this study was to assess vertical transmission of HIV among pregnant women who initially had false-negative rapid HIV tests in South African antenatal care (ANC) clinics.

METHODS

Pregnant participants were enrolled in a diagnostic study that used nucleic acid amplification testing (NAAT) to screen for early HIV infection among individuals who tested negative on rapid HIV tests used at the point-of-care (POC) facilities. Participants were enrolled from four ANC clinics in the Tshwane district of South Africa. All NAAT-positive participants were recalled to the clinics for further management. Vertical transmission was assessed among exposed infants whose HIV polymerase chain reaction (PCR) results were available.

RESULTS

This study enrolled 8208 pregnant participants who tested negative on rapid HIV tests between 2013 and 2016. Their median age was 26 years (interquartile range [IQR]: 23-30). NAAT detected HIV infections in 0.6% (n = 49; 95% confidence interval {CI}: 0.5-0.8) of all study participants. The distribution of these infections among the four clinics ranged from 0.3%- 1.1%, but this was not statistically significant (p = 0.07). Forty-seven participants (95.9%) were successfully recalled and referred for antiretroviral treatment initiation as part of prevention of MTCT (PMTCT). Most women with newly diagnosed HIV infection presented for the first ANC visit in the second (61.9%, n = 26) and third (31.0%, n = 13) trimesters. HIV PCR results were available for thirty-two infants, three of whom tested positive (9.4%; 95% CI: 1.98-25.02).

CONCLUSIONS

This study showed that supplemental HIV testing for pregnant women led to earlier linkage to the PMTCT programme. Inaccurate diagnosis of HIV infection at ANC clinics is likely to undermine the efforts of eliminating MTCT particularly in HIV-endemic settings.

Pregnancy and Infant Outcomes Among Women Using the Dapivirine Vaginal Ring in Early Pregnancy

BACKGROUND

Monthly use of the dapivirine vaginal ring has been shown to be safe and effective for HIV-1 prevention in nonpregnant reproductive-aged women. The impact of dapivirine on pregnancy outcomes and infant is not known. We compared pregnancy incidence and outcomes by study arm among HIV-1-uninfected women who became pregnant while participating in MTN-020/ASPIRE.

METHODS

ASPIRE was a randomized, double-blind, placebo-controlled phase III safety and effectiveness study of the dapivirine ring for HIV-1 prevention. Sexually active women aged 18-45 years from Malawi, South Africa, Uganda, and Zimbabwe were enrolled. Urine pregnancy tests were performed monthly, and, if positive, study product was withheld during pregnancy and breastfeeding. Pregnancy-related outcomes included the following: pregnancy incidence, pregnancy outcomes (live birth, preterm birth, pregnancy loss, and congenital anomalies), and infant growth.

RESULTS

Of 2629 women enrolled in ASPIRE, 169 became pregnant during follow-up, resulting in 179 incident pregnancies and 181 pregnancy outcomes. No difference in pregnancy incidence by study arm was observed (hazard ratio = 0.93; 95% confidence interval: 0.68 to 1.26). The distribution of pregnancy outcomes was similar by study arm, and no difference was noted in the frequency or pattern of congenital anomalies or infant growth parameters by study arm.

CONCLUSIONS

Dapivirine use in the periconception period does not seem to be associated with adverse effects on pregnancy or infant outcomes. Our findings provide support for additional safety studies of the dapivirine ring throughout pregnancy.

Cost-effectiveness analysis of infant feeding modalities for virally suppressed mothers in Canada living with HIV

OBJECTIVE

The aim of the study was to determine whether exclusive breastfeeding or exclusive formula feeding is more cost-effective when a Canadian mother with HIV is adherent to antiretroviral therapy and has full virologic suppression.

DESIGN

Current Canadian guidelines recommend that mothers with HIV practice exclusive formula feeding. This contradicts the updated World Health Organization (WHO) guidelines which recommend that mothers with HIV should breastfeed for ≥12 months while receiving support for antiretroviral therapy adherence. Due to the economic and health risks and benefits associated with each modality, there remains expert disagreement on whether the WHO recommendations should be adopted in high-income countries.

METHODS

A microsimulation model was developed to estimate lifetime costs and effectiveness (i.e., infant's quality-adjusted life years) of a hypothetical group of 1,000,000 initially healthy, HIV-negative infants, if the mother with HIV was on antiretroviral therapy with full virologic suppression and either exclusive breastfeeding or exclusive formula feeding. The model was developed from the economic perspective of the Ontario Ministry of Health, taking into account direct costs associated with infant feeding modality as well as related indirect costs born out of the child's lifetime health outcomes. Uncertainties related to model parameters were evaluated using one-way and probabilistic sensitivity analyses.

RESULTS

In comparison to exclusive formula feeding, exclusive breastfeeding was the dominant feeding modality (i.e., less costly and more effective) yielding cost-savings of $13,812 per additional quality-adjusted life year gained. Neither one-way nor probabilistic sensitivity analyses altered the conclusions.

CONCLUSIONS

Despite the risk of HIV transmission, exclusive breastfeeding was more cost-effective than exclusive formula feeding. These findings merit review of current infant feeding guidelines for mothers with HIV living in high-income countries.

HIV in pregnancy: Identification of intrapartum and perinatal HIV exposures

The benefits of human immunodeficiency virus (HIV) testing in pregnancy, when combined with appropriate maternal antiretroviral therapy and intrapartum and postnatal prophylaxis, are well established. The vertical rate of transmission of HIV in North America is now well below 2%. Efforts must continue to ensure that these benefits are sustained. Women who have received little or no prenatal care and those who present for delivery with unknown HIV status need immediate testing. As more infants are exposed to antiretroviral agents, strategies need to be implemented to ensure adequate follow-up of these infants. Issues relating to the identification of HIV-exposed infants are highlighted.

Strategies for screening cord blood for a public cord blood bank in high HIV prevalence regions

assay suggest that it could be used for the routine screening of CB units in conjunction with currently recommended maternal screening to reduce the risk of transplant transmissible infection.

Acceptability of and Adherence to an Antiretroviral-Based Vaginal Microbicide among Pregnant Women in the United States

The MTN-008 trial was the first multi-dose study conducted to evaluate the safety of a microbicide gel (2:1 randomized to tenofovir 1% or hydroxycellulose (HEC) placebo gel) during pregnancy. The study aim was to evaluate safety, tolerability and pharmacokinetics of the study products. Procedures included daily gel administration, with Day 0 and Day 6 in clinic, and Days 1-5 at home. Because pregnancy may pose unique challenges to consistent gel use and acceptability, evaluation of adherence and acceptability was a secondary objective of the trial. The study enrolled healthy, HIV-negative, pregnant women aged 18-40 in Pittsburgh, PA and Birmingham, AL, USA in 2 consecutive groups: cohort 1 was 37-39 weeks gestation, cohort 2 was 34-36 weeks. Ninety-one women completed the study (45 and 46 in each cohort, respectively) and were evaluable per protocol. Adherence was evaluated using self-reports: participants completed a web-based computer-assisted self-interview (CASI) at Days 0 and 6 about gel attitudes and behaviors. At Day 6 trained research staff conducted a short interviewer-administered questionnaire with both structured and open-ended questions. Frequencies of quantitative data were tabulated in SAS and descriptive statistics are presented; open-ended textual data were summarized by a behavioral scientist experienced in qualitative analysis. Participants reported generally neutral perceptions of gel characteristics. A small number of women (7-8%) reported pain (6/90), other physical discomfort (7/90), or mental discomfort (7/90) associated with the process of applicator insertion. About 5% reported the same for the gel itself. Two-thirds (61/90) thought the gel was runny, many complained of bothersome gel leakage and several cited this reason for not inserting a full dose. The majority were not worried the gel would cause problems for their pregnancy or babies. Ninety-seven percent (83/86) said they would use the gel in the future if they were pregnant, and 90% (81/90) when nonpregnant. Self-reported adherence was high with 88% (79/90) reporting daily gel use on both the computerized and interviewer-administered questionnaires. The majority (67/90) reported no difficulty with daily use. However, drug was undetectable (<0.31 ng/mL) among 45% (27/60; 95% CI 32-58%) of the women on active product prior to observed dosing at Day 6. The most common reason for reported nonuse (N = 6) was forgetting. Study gel was generally acceptable, but many complained of a runny consistency (61/90) and leakage (83/90). No frequent or strong concerns about the effects of the study gel on the pregnancy/fetus were reported. Self-reported adherence to study gel self-administered at home for 5 days was high, however plasma drug levels suggest actual use may have been considerably lower. Findings from this study can provide insights relevant to use of other antiretroviral-based, vaginally-inserted HIV prevention methods during pregnancy.

Detection of Acute and Early HIV-1 Infections in an HIV Hyper-Endemic Area with Limited Resources

BACKGROUND

Two thirds of the world's new HIV infections are in sub-Saharan Africa. Acute HIV infection (AHI) is the time of virus acquisition until the appearance of HIV antibodies. Early HIV infection, which includes AHI, is the interval between virus acquisition and establishment of viral load set-point. This study aimed to detect acute and early HIV infections in a hyper-endemic setting.

METHODS

This was a cross-sectional diagnostic study that enrolled individuals who had negative rapid HIV results in five clinics in South Africa. Pooled nucleic acid amplification testing (NAAT) was performed, followed by individual sample testing in positive pools. NAAT-positive participants were recalled to the clinics for confirmatory testing and appropriate management. HIV antibody, p24 antigen, Western Blot and avidity tests were performed for characterization of NAAT-positive samples.

RESULTS

The study enrolled 6910 individuals with negative rapid HIV results. Median age was 27 years (interquartile range {IQR}: 23-31). NAAT was positive in 55 samples, resulting in 0.8% newly diagnosed HIV-infected individuals (95% confidence interval {CI}: 0.6-1.0). The negative predictive value for rapid HIV testing was 99.2% (95% CI: 99.0-99.4). Characterization of NAAT-positive samples revealed that 0.04% (95% CI: 0.000-0.001) had AHI, 0.3% (95% CI: 0.1-0.4) had early HIV infection, and 0.5% (95% CI: 0.5-0.7) had chronic HIV infection. Forty-seven (86%) of NAAT-positive participants returned for follow-up at a median of 4 weeks (IQR: 2-8). Follow-up rapid tests were positive in 96% of these participants.

CONCLUSIONS

NAAT demonstrated that a substantial number of HIV-infected individuals are misdiagnosed at South African points-of-care. Follow-up rapid tests done within a 4 week interval detected early and chronic HIV infections initially missed by rapid HIV testing. This may be a practical and affordable strategy for earlier detection of these infections in resource-constrained settings. Newer molecular tests that can be used at the points-of-care should be evaluated for routine diagnosis of HIV in hyper-endemic settings.

A randomized safety and pharmacokinetic trial of daily tenofovir 1% gel in term and near-term pregnancy

INTRODUCTION

Vaginal tenofovir (TFV) 1% gel may reduce incident HIV-1 and herpes simplex virus 2 infection. Pregnancy may increase risk of HIV acquisition, and incident HIV in pregnancy potentiates perinatal HIV transmission. Our objective was to investigate the safety and pharmacokinetics of seven days of TFV 1% vaginal gel in term and near-term pregnancy.

METHODS

Ninety-eight healthy pregnant women, stratified to a term cohort followed by a near-term cohort, were enrolled into a 2:1 randomized, double-blinded, placebo-controlled trial. Women received TFV or placebo gel for seven consecutive days with pharmacokinetic sampling on days 0 and 6. Maternal and cord blood were collected at delivery. Primary end points included laboratory and genital adverse events, adverse pregnancy and neonatal outcomes, and maternal TFV levels.

RESULTS

Most adverse events were grade 1 and none of the grade 3 or 4 adverse events were related to study product. There was no significant difference in safety end points between the two pregnancy cohorts (p=0.18); therefore, their data were combined. Primary safety end point rates were similar for mothers randomized to the TFV gel vs placebo arm (72.7 and 68.8%, p=0.81). The same was true for newborns in the TFV gel vs placebo arms (4.5% vs 6.3%, p=0.66). All women randomized to TFV had quantifiable serum levels within eight hours of dosing, with low overall median (interquartile range) day 0 and day 6 peak values (3.8 (2.0 to 7.0) and 5.8 (2.6 to 9.4) ng/mL, respectively).

CONCLUSIONS

Daily TFV 1% vaginal gel use in term and near-term pregnancy appears to be safe and produces low serum drug levels.

Performing Drug Safety Research During Pregnancy and Lactation: Biomedical HIV Prevention Research as a Template

Evidence-based guidance regarding use of nearly all pharmaceuticals by pregnant and lactating women is limited. Models for performing research may assist in filling these knowledge gaps. Internationally, reproductive age women are at high risk of human immunodeficiency virus (HIV) acquisition. Susceptibility to HIV infection may be increased during pregnancy, and risk of maternal-child transmission is increased with incident HIV infection during pregnancy and lactation. A multidisciplinary meeting of experts was convened at the United States National Institutes of Health to consider paradigms for drug research in pregnancy and lactation applicable to HIV prevention. This report summarizes the meeting proceedings and describes a framework for research on candidate HIV prevention agent use during pregnancy and lactation that may also have broader applications to other pharmaceutical products.

Paediatric HIV infection: the potential for cure

Recent anecdotal reports of HIV-infected children who received early antiretroviral therapy (ART) and showed sustained control of viral replication even after ART discontinuation have raised the question of whether there is greater intrinsic potential for HIV remission, or even eradication ('cure'), in paediatric infection than in adult infection. This Review describes the influence of early initiation of ART, of immune ontogeny and of maternal factors on the potential for HIV cure in children and discusses the unique immunotherapeutic opportunities and obstacles that paediatric infection may present.

The importance of studying antimicrobials in pregnancy

Pregnant women and their unborn fetuses are a population with unique and heightened risks from a variety of infectious conditions. Sizable percentages of pregnant women receive antimicrobials during pregnancy for various indications. Despite this, many of the available antimicrobials in current use have inadequate data to fully inform evidence-based dosage recommendations to optimize clinical impact. Because of non-inclusion of pregnant women in clinical trials this situation exists and challenges the obstetric providers' ability to provide evidence-based treatment. Examples of the impact of the current status of exclusion of pregnant women from participation in clinical trials will be highlighted. In addition, successful models of research permitting safe and informative investigations of various antimicrobials in pregnancy will be discussed.

Are infants unique in their ability to be "functionally cured" of HIV-1?

The recent report of an infant that appears to have achieved a "functional cure" of HIV-1 following receipt of antiretroviral therapy (ART) within 30 hours of birth raises many questions: was the child infected? Was this result due to unique features of this particular infant's immune system, the immune system of infants or the very early initiation of effective ART? In this manuscript, we discuss the pathogenesis of HIV-1 in infants, highlighting the unique features of infant immune development and how these may inform efforts to cure HIV infection. We will also compare the path to infant "cure" to cures in adults.

Immunology of pediatric HIV infection

Most infants born to human immunodeficiency virus (HIV)-infected women escape HIV infection. Infants evade infection despite an immature immune system and, in the case of breastfeeding, prolonged repetitive exposure. If infants become infected, the course of their infection and response to treatment differs dramatically depending upon the timing (in utero, intrapartum, or during breastfeeding) and potentially the route of their infection. Perinatally acquired HIV infection occurs during a critical window of immune development. HIV's perturbation of this dynamic process may account for the striking age-dependent differences in HIV disease progression. HIV infection also profoundly disrupts the maternal immune system upon which infants rely for protection and immune instruction. Therefore, it is not surprising that infants who escape HIV infection still suffer adverse effects. In this review, we highlight the unique aspects of pediatric HIV transmission and pathogenesis with a focus on mechanisms by which HIV infection during immune ontogeny may allow discovery of key elements for protection and control from HIV.

Antibody maturation and viral diversification in HIV-infected women

INTRODUCTION

The Post-exposure Prophylaxis in Infants (PEPI)-Malawi trial evaluated infant antiretroviral regimens for prevention of post-natal HIV transmission. A multi-assay algorithm (MAA) that includes the BED capture immunoassay, an avidity assay, CD4 cell count, and viral load was used to identify women who were vs. were not recently infected at the time of enrollment (MAA recent, N = 73; MAA non-recent, N = 2,488); a subset of the women in the MAA non-recent group known to have been HIV infected for at least 2 years before enrollment (known non-recent, N = 54). Antibody maturation and viral diversification were examined in these women.

METHODS

Samples collected at enrollment (N = 2,561) and 12-24 months later (N = 1,306) were available for serologic analysis using the BED and avidity assays. A subset of those samples was used for analysis of viral diversity, which was performed using a high resolution melting (HRM) diversity assay. Viral diversity analysis was performed using all available samples from women in the MAA recent group (61 enrollment samples, 38 follow-up samples) and the known non-recent group (43 enrollment samples, 22 follow-up samples). Diversity data from PEPI-Malawi were also compared to similar data from 169 adults in the United States (US) with known recent infection (N = 102) and known non-recent infection (N = 67).

RESULTS

In PEPI-Malawi, results from the BED and avidity assays increased over time in the MAA recent group, but did not change significantly in the MAA non-recent group. At enrollment, HIV diversity was lower in the MAA recent group than in the known non-recent group. HRM diversity assay results from women in PEPI-Malawi were similar to those from adults in the US with known duration of HIV infection.

CONCLUSIONS

Antibody maturation and HIV diversification patterns in African women provide additional support for use of the MAA to identify populations with recent HIV infection.

Effect of natural and ARV-induced viral suppression and viral breakthrough on anti-HIV antibody proportion and avidity in patients with HIV-1 subtype B infection

BACKGROUND

Viral suppression and viral breakthrough impact the humoral immune response to HIV infection. We evaluated the impact of viral suppression and viral breakthrough on results obtained with two cross-sectional HIV incidence assays.

METHODS

All samples were collected from adults in the US who were HIV infected for >2 years. Samples were tested with the BED capture enzyme immunoassay (BED-CEIA) which measures the proportion of IgG that is HIV-specific, and with an antibody avidity assay based on the Genetic Systems 1/2+ O ELISA. We tested 281 samples: (1) 30 samples from 18 patients with natural control of HIV-1 infection known as elite controllers or suppressors (2) 72 samples from 18 adults on antiretroviral therapy (ART), with 1 sample before and 2-6 samples after ART initiation, and (3) 179 samples from 20 virally-suppressed adults who had evidence of viral breakthrough receiving ART (>400 copies/ml HIV RNA) and with subsequent viral suppression.

RESULTS

For elite suppressors, 10/18 had BED-CEIA values <0.8 normalized optical density units (OD-n) and these values did not change significantly over time. For patients receiving ART, 14/18 had BED-CEIA values that decreased over time, with a median decrease of 0.42 OD-n (range 0.10 to 0.63)/time point receiving ART. Three patterns of BED-CEIA values were observed during viral breakthrough: (1) values that increased then returned to pre-breakthrough values when viral suppression was re-established, (2) values that increased after viral breakthrough, and (3) values that did not change with viral breakthrough.

CONCLUSIONS

Viral suppression and viral breakthrough were associated with changes in BED-CEIA values, reflecting changes in the proportion of HIV-specific IgG. These changes can result in misclassification of patients with long-term HIV infection as recently infected using the BED-CEIA, thereby influencing a falsely high value for cross-sectional incidence estimates.

Progress, challenges, and new opportunities for the prevention of mother-to-child transmission of HIV under the US President's Emergency Plan for AIDS Relief

In June 2011, the Joint United Nations Programme on HIV/AIDS, the US President's Emergency Plan for AIDS Relief (PEPFAR), and other collaborators outlined a transformative plan to virtually eliminate pediatric AIDS worldwide. The ambitious targets of this initiative included a 90% reduction in new pediatric HIV infections and a 50% reduction in HIV-related maternal mortality--all by 2015. PEPFAR has made an unprecedented commitment to the expansion and improvement of prevention of mother-to-child HIV transmission (PMTCT) services globally and is expected to play a critical role in reaching the virtual elimination target. To date, PEPFAR has been instrumental in the success of many national programs, including expanded coverage of PMTCT services, an enhanced continuum of care between PMTCT and HIV care and treatment, provision of more efficacious regimens for antiretroviral prophylaxis, design of innovative but simplified PMTCT approaches, and development of new strategies to evaluate program effectiveness. These accomplishments have been made through collaborative efforts with host governments, United Nations agencies, other donors (eg, the Global Fund for AIDS, Tuberculosis, and Malaria), nongovernmental organizations, and private sector partners. To successfully meet the ambitious global targets to prevent new infant HIV infections, PEPFAR must continue to leverage the existing PMTCT platform, while developing innovative approaches to rapidly expand quality HIV services. PEPFAR must also carefully integrate PMTCT into the broader combination prevention agenda for HIV, so that real progress can be made toward an "AIDS-free generation" worldwide.