Evidence of horizontal gene transfer within porB in 19 018 whole-genome Neisseria spp. isolates: a global phylogenetic analysis

Abstract

The PorB porins are the major pore-forming proteins in the genus Neisseria . The trimeric PorB porins consist of 16 highly conserved transmembrane domains that form an amphipathic β-sheet connected by short periplasmic turns and eight extracellular hydrophilic loops. These loops are immunogenic and also play an important role in mediating antimicrobial influx. This study sought to (i) characterize the variations in Neisserial loop 3(355–438 bp) associated with intermediate resistance to penicillin/tetracycline and (ii) evaluate if there was evidence of horizontal gene transfer in any of the loops. We collated an integrated database consisting of 19 018 Neisseria spp. genomes – 17 882 Neisseria gonorrhoeae , 114 Neisseria meningitidis and 1022 commensal Neisseria spp. To identify the porB alleles, a gene-by-gene approach (chewBBACA) was employed. To evaluate the presence of recombination events, the Recombination Detection Programme (RDP4) was used. In total, 3885 porB alleles were detected. Paralogues were identified in 17 Neisseria isolates. Putative recombination was identified in loop regions. Intraspecies recombination among N. gonorrhoeae isolates and interspecies recombination between N. meningitidis and commensal Neisseria spp., and N. gonorrhoeae and N. lactamica were identified. Here, we present a large-scale study of 19 018 Neisseria isolates to describe recombination and variation in the porB gene. Importantly, we found putative recombination in loop regions between the pathogenic and non-pathogenic Neisseria spp. These findings suggest the need for pheno- and genotypic surveillance of antimicrobial susceptibility in commensal Neisseria spp. to prevent the emergence of AMR in the pathogenic Neisseria . This article contains data hosted by Microreact.

Keywords: Neisseria; PorB1a; Porb1b; commensal Neisseria; phylogenetics; porin.