title: Comparative Genomic Analysis of Two Serotype 1/2bListeria monocytogenesIsolates from Analogous Environmental Niches Demonstrates the Influence of Hypervariable Hotspots in Defining Pathogenesis.
abstract: The vast majority of clinical human listeriosis cases are caused by serotype 1/2a, 1/2b, 1/2c, and 4b isolates ofListeria monocytogenes. The ability ofL. monocytogenesto establish a systemic listeriosis infection within a host organism relies on a combination of genes that are involved in cell recognition, internalization, evasion of host defenses, andin vitrosurvival and growth. Recently, whole genome sequencing and comparative genomic analysis have proven to be powerful tools for the identification of these virulence-associated genes inL. monocytogenes. In this study, two serotype 1/2b strains ofL. monocytogeneswith analogous isolation sources, but differing infection abilities, were subjected to comparative genomic analysis. The results from this comparison highlight the importance of accessory genes (genes that are not part of the conserved core genome) inL. monocytogenespathogenesis. In addition, a number of factors, which may account for the perceived inability of one of the strains to establish a systemic infection within its host, have been identified. These factors include the notable absence of theListeriapathogenicity island 3 and the stress survival islet, of which the latter has been demonstrated to enhance the survival ability ofL. monocytogenesduring its passage through the host intestinal tract, leading to a higher infection rate. The findings from this research demonstrate the influence of hypervariable hotspots in defining the physiological characteristics of aL. monocytogenesstrain and indicate that the emergence of a non-pathogenic isolate ofL. monocytogenesmay result from a cumulative loss of functionality rather than by a single isolated genetic event.
authors.affiliation: Teagasc Food Research Centre, Fermoy, Ireland; Department of Biological Sciences, Cork Institute of Technology, Bishopstown, Ireland.
authors.forename: Aidan
authors.initials: A
authors.lastname: Casey
authors.affiliation: Teagasc Food Research Centre , Fermoy , Ireland.
authors.forename: Kieran
authors.initials: K
authors.lastname: Jordan
authors.affiliation: Department of Biological Sciences, Cork Institute of Technology , Bishopstown , Ireland.
authors.forename: Aidan
authors.initials: A
authors.lastname: Coffey
authors.affiliation: CSIRO Agriculture and Food , Werribee, VIC , Australia.
authors.forename: Edward M
authors.initials: EM
authors.lastname: Fox
authors.affiliation: Teagasc Food Research Centre , Fermoy , Ireland.
authors.forename: Olivia
authors.initials: O
authors.lastname: McAuliffe
keywords: DPC6895; LIPI-3; Listeria monocytogenes; attenuated virulence; comparative genomic analysis; hypervariable hotspots; pathogenesis; serotype 1/2b; stress survival islet