Virulence of transparent and opaque colony types of Neisseria gonorrhoeae for the genital tract of mice

Abstract

Summary. The virulence of transparent (Tr) and opaque (Op) colony types of Neisseria gonorrhoeae in the genital tract of female mice was evaluated at two stages of oestrous. Isogenic pairs of Tr and Op variants were isolated from N . gonorrhoeae strain 57-120. Both variants exhibited a T2 morphology, but only the Op variant possessed protein I1 (P. 11) in outer-membrane fractions. When administered by intravaginal inoculation Op gonococci were highly infective only for mice in late pro-oestrous, whereas Tr gonococci were virulent for mice at both late pro-oestrous and dioestrous. Gonococci recovered from the uterus were of both Tr and Op phenotypes in equal proportions when mice were infected at dioestrous with Tr cells. In contrast, ~9 0 % of recovered colonies were of Op phenotype when mice were infected at late pro-oestrous with either Op or Tr cells. These results indicate that the virulence of gonococci for the genital tract of female mice differs from that for the chicken embryo. Furthermore, gonococcal survival in the female genital tract might be attributable to phase variation from Tr to Op phenotypes.

In Vivo Selection for Neisseria gonorrhoeae Opacity Protein Expression in the Absence of Human Carcinoembryonic Antigen Cell Adhesion Molecules

“…Consistent with our observation, Kita et al reported changes in Opa phenotype with respect to the estrous cycle in experimentally infected SLC:ddY mice (35). These observations are consistent with the reported recovery of mostly opaque isolates and of transparent isolates from women in the proliferative and luteal phases of the menstrual cycle, respectively (26,27).…”

Variable Tandem Repeats Accelerate Evolution of Coding and Regulatory Sequences

“…Changes in the number of units of this pentameric repeat can cause frameshifts, and consequently the proteins are either correctly translated (phenotype ON) or not correctly translated (phenotype OFF) in different cells of the population (123) (Figure 5). This ON/OFF switching of phenotype occurs during infection and is believed to create variants in the bacterial population capable of surviving in the host (61). Other compelling examples come from Haemophilus influenzae, in which the outer membrane structure is also phase variable.…”

Beyond Junk-Variable Tandem Repeats as Facilitators of Rapid Evolution of Regulatory and Coding Sequences

“…In the bacterium, Neisseria gonorrhoeae , repeat variations in the P. II family of cell surface genes allow for evasion of the host immune system [54]. Changes in the CTCTT pentameric microsatellite repeat in the coding region of the membrane signal peptide of cell surface genes, can either lead to correct or incorrect translation of proteins [55].…”