A paradigm shift in the vaccine field is the recognition that vaccines have non-targeted ‘non-specific’ effects (NSEs) on the immune system,
beyond the induction of vaccine specific adaptive immunity. The gut microbiome significantly affects the development and regulation of the
immune system. Therefore, its composition may affect the individual response to vaccination.
Two vaccines recommended for the elderly are the annual seasonal influenza vaccine (sIV) and the Diphtheria Tetanus and acellular Pertussis
(DTaP) vaccine. The double blinded VITAL human trial, involving 400 young and elderly volunteers from Tasmania, Australia, is designed to assess
the NSEs of these vaccines on the immune system of the young and elderly. Participants were immunized with DTap followed by sIV, sIV alone or
DTap concurrently with the sIV. Herein we present initial assessment of the gastrointestinal microbiota (n=74) from the VITAL cohort.
Baseline faecal samples from 74 patients were collected and sequenced with shotgun metagenomic sequencing. This patient cohort had
an alpha diversity with an average Shannon’s diversity index of 4.45 while beta diversity showed no significant variance amongst the
patient cohort. Taxonomic classification against the Human Gastrointestinal Bacteria Genome Collection identified 61 out of 74 patient
samples with unclassified rates greater than 30%. To investigate the novel species within this cohort, 5 patient samples with high levels of
unclassified reads (>50%) were selected to perform bacterial culturing. Our 16S rRNA sequencing analysis on the resulting purified isolates
identified 17 putative novel species. Expanding the availability of genome sequenced bacterial isolates will provide a valuable resource to
further characterize the ecology of human microbial communities, which is paramount for the study of individual responses to vaccination
Jennifer C. Boer