Persistence of Two Genotypes of Neisseria gonorrhoeae during Transmission

Abstract

Isolates of Neisseria gonorrhoeae were tested using a highly discriminatory typing method, opa typing, to examine the genetic diversity over a 2-year study period of isolates from all consecutive patients with gonorrhea attending the Genitourinary Medicine clinic in Sheffield, United Kingdom. Two opa genotypes were detected throughout the 2-year time period and comprised 41% of all strains tested. The persistence of two opa types was investigated further to determine the apparent genetic stability, by examining the ability of isolates to undergo intragenic and intergenic recombination and mutation in vitro. Intragenic recombination or mutation involving the opa genes of N. gonorrhoeae in the selected isolates was not detected, but intergenic recombination did occur. opa genes of N. gonorrhoeae in vivo appear to diversify primarily through intergenic recombination. Intergenic recombination in vivo would require the presence of a mixed gonococcal infection, in which an individual is concurrently colonized with more than one strain of N. gonorrhoeae. We propose that the level of diversity of opa genotypes in a population is linked to the degree of sexual mixing of individuals and the incidence of mixed infections of N. gonorrhoeae.

Molecular Epidemiology of Neisseria gonorrhoeae in Amsterdam, The Netherlands, Shows Distinct Heterosexual and Homosexual Networks

“…Our observations of distinct heterosexual and MSM clusters with shared demographic characteristics in terms of their size and persistence correspond with several N. gonorrhoeae genotyping studies done in the United Kingdom, even though opa and por RFLP typing was performed by using different molecular techniques (6,10,12). In our study, for example, cluster G1 contained 59% female patients, 35% of whom were from a Surinamese/Antillean ethnic background.…”

“…This (1,10). DNA mutation and/or recombination cannot be ruled out and will certainly occur independent of the typing technique used, as it is known that N. gonorrhoeae opacity and porin proteins are subject to host immune responses (1,24).…”

Relative Contributions of Recombination and Mutation to the Diversification of the opa Gene Repertoire of Neisseria gonorrhoeae

“…Two sets of closely related isolates that had been characterized by opa typing (29) were available from a study of gonor- rhea in Sheffield between April 1995 and March 1997 (25,36), along with additional opa-typed isolates from the same study collected up to November 1997. Two prevalent strains were circulating during this 32-month period, previously identified by opa typing as opa type 1 and opa type 4, together making up 41% of the isolates studied (25).…”

“…Isolates from cases of gonorrhea in Sheffield between April 1995 and March 1997 were from the study of Martin et al (25,36). Additional isolates from Sheffield collected up to November 1997 were also used.…”

“…Additional isolates from Sheffield collected up to November 1997 were also used. Many of these isolates have been characterized by both opa typing (25,36) and NG-MAST (6), and detailed sexual contact tracing data are available. Isolates from mutually named recent sexual contacts were from this collection.…”