Vertical HIV-1 Transmission in the Setting of Maternal Broad and Potent Antibody Responses

Development of Maternal Antibodies Post ZIKV in Pregnancy is Associated with Lower Risk of Microcephaly and Structural Brain Abnormalities in Exposed Infants

BACKGROUND

We investigated the association between maternal neutralizing antibodies (nAb) to Zika virus (ZIKV) in pregnancy and neonatal outcomes.

METHODS

In pregnant participants with confirmed ZIKV infection, we determined trimester of infection, collected sera longitudinally, and measured nAbs via plaque reduction. In neonates, adverse outcomes included microcephaly (MC), structural brain abnormalities (SBA), hearing, and eye abnormalities. Associations between trimester of infection, nAbs, and neonatal outcomes were analyzed with Cox regression.

RESULTS

In total, 137 ZIKV-positive pregnant participants had neutralization assays performed during pregnancy and postdelivery. Infection rates were 29% in the first, 50% in the second, and 21% in the third trimester. Mean ZIKV nAb titer >2 weeks postinfection was 64 258 (SD 213 288). Ten percent of 90% plaque reduction neutralization assays (PRNT90) titers were <500, 10% 500-1000, 73% > 1000, and 7% did not have serologic follow-up; 15%. of infants had adverse findings. Protective factors against MC in 88 mothers with nAb titers available during pregnancy included infection later in gestation (adjusted hazard ratio [aHR], 0.06; P = .036) and adequate nAb titers (aHR, 0.17; P = .014). No SBA was associated with later infection in pregnancy (aHR, 0.16; P = .017) and adequate nAb titers (aHR, 0.34; P = .012). Adjusting for trimester, higher maternal nAb titers were associated with lower risk of MC and SBA. Seven of 137 participants (5.1%) had positive serum ZIKV polymerase chain reaction (PCR) results beyond 14 days (range, 35-269 days). Participants with ZIKV PCR positivity >60 days (n = 2) had infants with MC/SBA.

CONCLUSIONS

MC and SBA were less frequent in infants of mothers with higher ZIKV nAb titers during pregnancy.

Research on Maternal Vaccination for HIV Prevention

Despite increased uptake of antiretroviral therapy (ART) among pregnant people living with human immunodeficiency virus (HIV), vertical transmission remains the most important route of pediatric HIV acquisition. The numbers of HIV acquisitions in infancy have remained alarmingly stagnant in recent years. It is evident that additional strategies that can synergize with ART will be required to end the pediatric HIV epidemic. In this review, we discuss the potential for immune-based interventions that can be administered in conjunction with current ART-based strategies to the birthing parent for prevention of vertical transmission of HIV-1, and the potential challenges associated with each approach.

Characterizing HIV drug resistance in cases of vertical transmission in the VESTED randomized antiretroviral treatment trial

Introduction

VESTED (NCT03048422) compared the safety and efficacy of three antiretroviral treatment (ART) regimens in pregnant and postpartum women: dolutegravir+emtricitabine/tenofovir alafenamide fumarate; dolutegravir+emtricitabine/tenofovir disoproxil fumarate (TDF); efavirenz/emtricitabine/TDF. Vertical HIV transmission (VT) occurred to 4/617 (0.60%) live-born infants, who were evaluated for HIV drug resistance (HIVDR) and other risk factors.

Setting

In 2018-2020, pregnant (weeks-14-28) women living with HIV and ≤14 days of ART were enrolled at 22 international sites and followed with their infants through 50 weeks postpartum.

Methods

HIV sequences derived by single genome amplification (SGA) from longitudinally collected specimens were assessed from VT Cases for HIVDR in protease, reverse transcriptase, integrase, and the nef 3'polypurine tract (3'PPT).

Results

The four Case mothers were prescribed efavirenz-based-ART for 1-7 days prior to randomization to study ART. Their infants received postnatal nevirapine+/-zidovudine prophylaxis and were breastfed. A total of 833 SGA sequences were derived. The "major" (Stanford HIVDR Score ≥60) non-nucleoside reverse transcriptase inhibitor (NNRTI) mutation (K103N) was detected persistently in one viremic mother, and likely contributed to VT of HIVDR. Major NNRTI HIVDR mutations were detected in all three surviving infants. No integrase, nor high frequencies of 3'PPT mutations conferring dolutegravir HIVDR were detected. The timing of HIV infant diagnosis, plasma HIV RNA levels and HIVDR suggests one in utero, one peripartum, one early, and one late breastfeeding transmission.

Conclusions

VT was rare. New-onset NNRTI HIVDR in Case mothers was likely from efavirenz-ART prescribed prior to study dolutegravir-ART, and in one case appeared transmitted to the infant despite nevirapine prophylaxis.

3D human tissue models and microphysiological systems for HIV and related comorbidities

Three-dimensional (3D) human tissue models/microphysiological systems (e.g., organs-on-chips, organoids, and tissue explants) model HIV and related comorbidities and have potential to address critical questions, including characterization of viral reservoirs, insufficient innate and adaptive immune responses, biomarker discovery and evaluation, medical complexity with comorbidities (e.g., tuberculosis and SARS-CoV-2), and protection and transmission during pregnancy and birth. Composed of multiple primary or stem cell-derived cell types organized in a dedicated 3D space, these systems hold unique promise for better reproducing human physiology, advancing therapeutic development, and bridging the human-animal model translational gap. Here, we discuss the promises and achievements with 3D human tissue models in HIV and comorbidity research, along with remaining barriers with respect to cell biology, virology, immunology, and regulatory issues.

Infant feeding: emerging concepts to prevent HIV transmission

PURPOSE OF REVIEW

HIV screening in pregnancy, universal suppressive antiretroviral therapy (ART) and breastfeeding avoidance can almost completely prevent vertical transmission of HIV. Breastfeeding is associated with an additional risk of transmission, although this risk is extremely low with suppressive maternal ART. This minimal risk must be balanced with the benefits of breastfeeding for women living with HIV (WLHIV) and their infants. Guidance in high-income countries has evolved, moving towards supported breast feeding for women on suppressive ART.

RECENT FINDINGS

Breastmilk transmission accounts for an increasing proportion of new infant infections globally. The majority of transmission data comes from studies including women not on suppressive ART. Breastmilk transmissions in the context of undetectable viral load have rarely occurred, although risk factors remain unclear. Outcome data on supported breastfeeding are accumulating, providing evidence for guidelines and informing infant feeding decisions. Long-acting ART for maternal preexposure prophylaxis or treatment, and infant postnatal prophylaxis are promising future options.

SUMMARY

Breastfeeding on suppressive ART has a very low risk of vertical transmission and can have multiple benefits for WLHIV and their infants. However, caution is advised with relaxation of breastfeeding guidance so as not to jeopardise the global goal of elimination of vertical transmission by 2030.