Impact of Gut Microbiota on Immunogenicity to Covid-19 Vaccines in Plwh

ABSTRACT

Background: Immune responses to SARS-CoV-2 vaccines in people living with HIV (PLWH) have been the focus of several recent studies. As the gut microbiome can influence vaccine immunogenicity, in this study we are the first to investigate whether the baseline gut microbiota can predict immune responses to the BNT162b2 SARS-CoV-2 vaccine in people living with HIV (PLWH) and healthy controls (HC). Method(s) Fecal samples were collected from PLWH (n=68) and HC (n=75) at baseline, prior to the first vaccine dose, to extract DNA for 16S rRNA sequencing. The individuals were part of the COVAXID Clinical trial, where humoral and cellular responses to SARS-CoV-2 vaccine were evaluated on day 35 after the first dose. Comprehensive bioinformatic tools were used for bacterial identification to further reveal the associations between gut microbiota and SARS-CoV-2 antibody, spike CD4+ T cell responses, and clinical parameters such as age, gender, CD4/CD8 ratio, and length of antiretroviral (ART) treatment. Result(s) At day 35 post vaccination, HC showed significantly higher spike IgG titers than PLWH (p=0.0001). Interestingly, both phylogenetic and alpha-diversity were negatively correlated with antibody titers, in the whole cohort and within groups. Similarly, individuals with low alpha-diversity had higher levels of spike specific CD4+T-cell responses. Agathobacter, Lactobacillus, Bacteroides, and Lachnospira were positively correlated with both antibody levels and spike-specific CD4+ T-cell responses while Methanobrevibacter, Marvinbryantia, Cloacibacillus, and Succinivibrio have a negative one. Within the PLWH group, the gut microbiota taxa associated with CD4+ counts, such as Lachnospira (p=0.002), Oscillibacter (p=0.019) and Flavonifractor (p=0.017), were found to be positively correlated with spike IgG levels. Additionally, the length of ART treatment and CD4/CD8 ratio displayed a positive association with bacterial diversity. Notably, different microbiome profiles and immune status in PLWH, affect their immune responses to vaccination. Conclusion(s) Our results show potential associations between gut microbiota diversity and spike IgG responses after COVID-19 vaccination. These findings were consistent in the whole cohort, albeit group differences between the microbiome compositions in PLWH and HC were observed. Based on our findings, we propose that microbiome modulation could optimize immunogenicity to SARS-Cov-2 vaccines.