Immune responses to oral poliovirus vaccine in HIV-exposed uninfected Zimbabwean infants

Reduced anti-viral IgG repertoire in HIV-exposed but uninfected infants compared to HIV-unexposed infants

Infants who are HIV exposed but uninfected (iHEU) have higher risk of viral infections compared to infants who are HIV unexposed (iHUU). We explored the effect of intrauterine HIV exposure on the infant antibody repertoire by quantifying plasma immunoglobulin (Ig) G against 206 eukaryote-infecting viruses using phage immunoprecipitation sequencing (PhiPSeq) in iHEU and iHUU at birth and 36 weeks of life. Maternal HIV infection altered the infant IgG repertoire against eukaryote-infecting viruses at birth, resulting in significantly lower antibody breadth and diversity among iHEU compared to iHUU. Neonatal anti-viral IgG repertoire was dominated by antibodies against viruses belonging to the Herpesviridae family, although, by 36 weeks, this had shifted toward antibodies against enteroviruses, likely due to waning of maternal-derived antibodies and polio vaccine-induced antibody responses as expected. The observed reduced anti-viral IgG repertoire breadth and diversity acquired at birth in iHEU might contribute to the increased rates of viral infections among iHEU during early life.

Bifidobacterium infantis associates with T cell immunity in human infants and is sufficient to enhance antigen-specific T cells in mice

Bacille Calmette-Guerin (BCG) vaccine can elicit good TH1 responses in neonates. We hypothesized that the pioneer gut microbiota affects vaccine T cell responses. Infants who are HIV exposed but uninfected (iHEU) display an altered immunity to vaccination. BCG-specific immune responses were analyzed at 7 weeks of age in iHEU, and responses were categorized as high or low. Bifidobacterium longum subsp. infantis was enriched in the stools of high responders, while Bacteroides thetaiotaomicron was enriched in low responders at time of BCG vaccination. Neonatal germ-free or SPF mice orally gavaged with live B. infantis exhibited significantly higher BCG-specific T cells compared with pups gavaged with B. thetaiotaomicron. B. infantis and B. thetaiotaomicron differentially affected stool metabolome and colonic transcriptome. Human colonic epithelial cells stimulated with B. infantis induced a unique gene expression profile versus B. thetaiotaomicron. We thus identified a causal role of B. infantis in early-life antigen-specific immunity.

Maternal HIV and child anthropometric outcomes over time: an analysis of Zimbabwe demographic health surveys

OBJECTIVES

To understand the association between children's anthropometric measures and maternal HIV status in Zimbabwe and to determine whether these relationships changed over time.

DESIGN

Data from Demographic Health Surveys in Zimbabwe rounds 2005, 2010, and 2015 were used to conduct cross-sectional analyses of child anthropometric measures (stunting, underweight, and wasting).

METHODS

Using separate logistic regression models for each of the anthropometric measures, we estimated the adjusted prevalence odds ratio (OR) of stunting, underweight, and wasting in children according to maternal HIV status. Moreover, we evaluated an interaction by survey year to evaluate change over time.

RESULTS

Children of mothers with HIV had 32% greater odds [OR = 1.32, 95% confidence interval (CI) 1.16-1.5] of stunting, 27% greater odds (OR = 1.27, 95% CI 1.1-1.48) of underweight status and 7% greater odds (OR = 1.07, 95% CI 0.81-1.42) of wasting status, than children of mothers without HIV. These associations between maternal HIV status and child undernutrition did not differ by year (P > 0.05 for all interaction terms).

CONCLUSION

In Zimbabwe, having a mother who tested positive for HIV at the time of the survey has been associated with greater child undernutrition over the last two decades with no significant change by survey round. This emphasizes the need for continued programming to address nutritional deficiencies, sanitation, and infectious disease prevention in this high-risk population. The greatest impact of maternal HIV status has been on child stunting and underweight, associated with poor long-term child development.

Effect of HIV-exposure and timing of anti-retroviral treatment on immunogenicity of trivalent live-attenuated polio vaccine in infants

Introduction

The prevalence of HIV infection in South African pregnant women has been approximately 30% over the past decade; however, there has been a steady decline in mother-to-child transmission of HIV from 8% in 2008 to <2% in 2015. We evaluated the immunogenicity of live-attenuated trivalent oral polio vaccine (OPV) following the primary vaccination series (doses at birth, 6, 10 and 14 weeks of age) in HIV-exposed uninfected (HEU), HIV-infected infants initiated on early anti-retroviral treatment (HIV+/ART+), HIV-infected infants on deferred ART (HIV+/ART-) and HIV-unexposed infants (HU) as the referent group.

Methods

Serum polio neutralization antibody titres were evaluated to serotype-1, serotype-2 and serotype-3 at 6, 10 and 18 weeks of age. Antibody titres ≥8 were considered seropositive and sero-protective.

Results

At 18 weeks of age, following the complete primary series of four OPV doses, no differences in GMTs, percentage of infants with sero-protective titres and median fold change in antibody titre (18 weeks vs 6 weeks) were observed in HEU infants (n = 114) and HIV+/ART+ infants (n = 162) compared to HU infants (n = 104) for the three polio serotypes. However, comparing HIV+/ART- infants (n = 70) to HU infants at 18 weeks of age, we observed significantly lower GMTs for serotype-1 (p = 0.022), serotype-2 (p<0.001) and serotype-3 (p<0.001), significantly lower percentages of infants with sero-protective titres for the three serotypes (p<0.001), and significantly lower median fold change in antibody titre for serotype-1 (p = 0.048), serotype-2 (p = 0.003) and serotype-3 (p = 0.008).

Conclusion

Delaying initiation of ART in HIV-infected infants was associated with an attenuated immune response to OPV following a four-dose primary series of vaccines, whereas immune responses to OPV in HIV-infected children initiated on ART early in infancy and HEU children were similar to HU infants.

Impact of maternal HIV exposure, feeding status, and microbiome on infant cellular immunity

At least one-third of infants born in sub-Saharan Africa have been exposed to the effects of maternal HIV infection and antiretroviral treatment. Intrauterine HIV exposure is associated with increased rates of morbidity and mortality in children. Although the mechanisms responsible for poor infant health with HIV-1 exposure are likely to be multifactorial, we posit that the maternal environment during gestation and in the perinatal period results in altered infant immunity and is possibly the strongest contributing factor responsible for the disproportionally high infectious events among HIV-exposed infants who remain HIV uninfected. This review provides a synthesis of studies reporting the impact of intrauterine HIV exposure, feeding practices, and microbiota on immune ontogeny in the first year of life in HIV-exposed uninfected infants.