PROJECT ABSTRACT
Infants born to HIV-infected mothers are at high risk for HIV acquisition. Additionally, HIV-exposed yet
uninfected infants display reduced vaccine responses and increased disease susceptibility compared to
unexposed infants. The development of certain T cell subsets, both in the mucosa and systemically, is
determined by the presence of specific microbes in the gut and may be important in determining adaptive
immunity. However, the gut microbiota of HIV-exposed uninfected (iHEU) infants differs from that of HIV-
unexposed (iHU) infants, since their mothers have altered gut microbiota. The gut virome also plays a central
role in modulating both the bacterial microbiota and immune response of adults, yet the association between
the infant enteric virome and cellular responses to vaccination has not yet been explored. This study proposes
that the enteric virome is one of the factors influencing the morbidity of HIV-exposed infants, either by directly
altering mucosal immunity or by altering the composition of enteric bacterial communities, as a consequence of
bacteriophage or other viral dynamics. This proposal will utilize an already funded, ongoing cohort to
longitudinally identify interactions between viruses, bacterial microbiota, and cellular responses to vaccination
in 40 iHEU and 40 iHU (Aim 1). Viral metagenome data will be integrated with bacterial community datasets
and T cell cytokine responses to BCG vaccination to identify viral and bacterial taxa correlated with BCG
responses. The effect of the expanded virome on bacterial microbiota and responses to BCG vaccination will
then be assessed for causality in gnotobiotic mouse models (Aim 2). The effect of the expanded iHEU viroem
on mucosa and peripheral gene expression will be assayed using single cell RNA sequencing in Aim 3.
Integrative analyses will be used to identify interactions between specific bacterial and viral taxa, as well as
their associated with BCG responses. Together, these Aims will identify mechanisms of gut dysbiosis in iHEU
and reveal potential therapeutics to restore health to this group. Collectively, this proposal will reveal how
maternal HIV infection shapes the enteric microbiome and immunity of associated infants.
