Virulence genes and previously unexplored gene clusters in four commensal 'Neisseria' spp. isolated from the human throat expands the neisserial gene repertoire

Commensal non-pathogenic spp. live within the human host alongside the pathogenic and and due to natural competence, horizontal gene transfer within the genus is possible and has been observed. Four distinct spp. isolates taken from the throats of two human volunteers have been assessed here using a combination of microbiological and bioinformatics techniques. Three of the isolates have been identified as biovar and one as . Specific gene clusters have been identified within these commensal isolate genome sequences that are believed to encode a Type VI Secretion System, a newly identified CRISPR system, a Type IV Secretion System unlike that in other spp., a hemin transporter, and a haem acquisition and utilization system. This investigation is the first to investigate these systems in either the non-pathogenic or pathogenic spp. In addition, the biovar possess previously unreported capsule loci and sequences have been identified in all four isolates that are similar to genes seen within the pathogens that are associated with virulence. These data from the four commensal isolates provide further evidence for a spp. gene pool and highlight the presence of systems within the commensals with functions still to be explored.