Characterization of capsule genes in non-pathogenic Neisseria species

Abstract

The genus Neisseria comprises a diverse group of commensal bacteria, which typically colonize the mucosal surfaces of humans and other animals. Neisseria meningitidis, the meningococcus, is notable for its potential to cause invasive meningococcal disease (IMD) in humans; however, IMD is comparatively rare, and meningococci normally colonize the nasopharynx asymptomatically. Possession of a polysaccharide capsule has been shown to be a prerequisite for disease in almost all IMD cases, and was previously considered unique to N. meningitidis, and potentially acquired by horizontal genetic transfer (HGT). Nevertheless, the capsule must also have some role in asymptomatic colonization and/or transmission, consistent with the existence of six non-disease-associated meningococcal capsule serogroups. In this study, full complements of putative capsule genes were identified in non-pathogenic Neisseria species, including Neisseria subflava and Neisseria elongata. These species contained genes for capsule transport and translocation homologous to those of N. meningitidis, as well as novel putative capsule synthesis genes. Phylogenetic analyses were consistent with the proposal that these genes were acquired by the meningococcus through HGT. In contrast with previous evolutionary models, however, the most parsimonious explanation of these data was that capsule transport genes had been lost in the common ancestor of the meningococcus, gonococcus, and their close relatives, and then reacquired by some meningococci. The most likely donor of the meningococcal transport genes was another Neisseria species.

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

“…Putative capsule genes with synthesis, transport, and translocation functions have previously been reported in the non-pathogenic Neisseria spp. [7] and similar to the previous findings for N. subflava, these putative regions were found to be contiguous in isolates KU1003-01 and RH3002v2g and one contig break in the locus occurs in KU1003-02 ( Fig. 3).…”

“…The structure of the capsule locus is well characterized and conserved in N. meningitidis [100,101] and phylogenetic analysis of Neisseria spp. capsule genes carried out by Clemence et al [7] highlighted that N. subflava was the closest encapsulated relative of N. meningitidis. Putative capsule genes with synthesis, transport, and translocation functions have previously been reported in the non-pathogenic Neisseria spp.…”

“…While capsule genes are often associated with N. meningitidis, they have also been identified within the non-pathogenic Neisseria spp. [7].…”

Genetic determinants of genus-level glycan diversity in a bacterial protein glycosylation system

“…While studies of single gene families may be phylogenetically informative [9], analyses of multiple genes whose products function in concerted biosynthetic and biochemical pathways may be particularly resourceful. Recent examples of this include genus-wide analyses of genes involved in pilus biogenesis [11], determining cell shape (rod to coccus transitions) [14], protein glycosylation [11,15], cytochrome c-based, electron transfer supporting dissimilatory nitrite reduction [16] and capsular polysaccharide expression [17].…”

Prevalência e fatores associados ao estado de portador de Neisseria spp. em núcleos familiares: estudo de base populacional

“…Embora ainda não seja claro, foi encontrada uma similaridade entre genes que determinam a presença de cápsulas polissacarídicas de Nm em NNP. Essa descoberta destaca o papel da cápsula na colonização assintomática e na transmissão da Nm e levanta uma hipótese sobre a evolução desses organismos e sua propensão de causar doenças (CLEMENCE et al, 2018).…”