Influence of non-polio enteroviruses and the bacterial gut microbiota on oral poliovirus vaccine response: a study from south India.

Oral poliovirus vaccine (OPV) is less immunogenic in LMIC countries. We tested whether bacterial and viral components of the intestinal microbiota are associated with this phenomenon. We assessed prevalence of enteropathogens using TaqMan array cards 14 days before and at vaccination in 704 Indian infants (6-11 months) receiving monovalent type3 OPV (CTRI/2014/05/004588). Non-polio enterovirus (NPEV) serotypes were identified by VP1 sequencing. In 120 infants, pre-vaccination bacterial microbiota was characterised by 16S rRNA sequencing. We detected 56 NPEV serotypes on the day of vaccination. Concurrent NPEVs were associated with a reduction in OPV seroconversion, consistent across species (odds ratios and 95% CIs of 0·57[0·36-0·90], 0·61[0·43-0·86], and 0·69[0·41-1·16] for species A, B, and C, respectively). Recently acquired enterovirus infections,detected at vaccination, but not 14 days earlier had greater interfering effect on mOPV3 sero-response compared to persistent infections,with enterovirus detected at both time points (44/127[35%] vs 63/129[49%] seroconversion,p=0.021). Abundance of specific bacterial taxa did not differ significantly according to OPV response, although microbiota diversity was higher in non-responders at the time of vaccination. Enteric viruses have greater impact on OPV response than the bacterial microbiota with recent enterovirus infections having greater inhibitory effect than persistent infections.