Group BStreptococcusCapsular Serotype Alters Vaginal Colonization Fitness

Abstract

Background Group B Streptococcus (GBS) remains a leading cause of infant morbidity and mortality. A candidate vaccine targets 6 GBS serotypes, offering a potential alternative to intrapartum antibiotic prophylaxis to reduce disease burden. However, our understanding of the contributions of specific capsule types to GBS colonization and disease remains limited. Methods Using allelic exchange, we generated isogenic GBS strains differing only in the serotype-determining region in 2 genetic backgrounds, including the hypervirulent clonal complex (CC) 17. Using a murine model of vaginal cocolonization, we evaluated the roles of the presence of capsule and of expression of specific capsular types in GBS vaginal colonization fitness independent of other genetic factors. Results Encapsulated wild-type strains COH1 (CC17, serotype III) and A909 (non-CC17, serotype Ia) outcompeted isogenic acapsular mutants in murine vaginal cocolonization. COH1 wild type outcompeted A909. Notably, expression of type Ia capsule conferred an advantage over type III capsule in both genetic backgrounds. Conclusions Specific capsule types may provide an advantage in GBS vaginal colonization in vivo. However, success of certain GBS lineages, including CC17, likely involves both capsule and noncapsule genetic elements. Capsule switching in GBS, a potential outcome of conjugate vaccine programs, may alter colonization fitness or pathogenesis.

Establishment and application of a rapid molecular diagnostic platform for the isothermal visual amplification of group B Streptococcus based on recombinase polymerase

“…Type III is the most virulent and infectious, causing more than half of serious infections. Type Ia was common in pregnant women; types Ia, Ib, II, and III were common in early neonatal infection; and type II and III were common in late neonatal infection (Russell et al, 2017;Dammann et al, 2022;Wadilo et al, 2023). Considering the multiple serotypes of GBS, the antigen-antibody test is prone to the risk of being false negative, leading this study to focus on the molecular diagnosis.…”

A group B Streptococcus indexed transposon mutant library to accelerate genetic research on an important perinatal pathogen

“…A909 is a sequence-type 7 GBS strain that expresses capsular serotype Ia. It was originally isolated from an infected neonate and has been used in many laboratory studies of GBS pathogenesis ( 22 , 51 , 61 , 63 – 69 ). GBS was grown in liquid cultures in tryptic soy (TS) broth (Fisher Scientific cat.…”

Interação de cepas de >i<Lactobacillus crispatus>/i< com >i<Streptococcus agalactiae>/i< em culturas celulares mimetizando o ambiente vaginal

“…O sorotipo III está associado a doenças invasivas, sendo o principal sorotipo isolado em casos de sepse tardia em neonatos (DAMMANN et al, 2022), também é frequentemente associado a casos de meningite SPELLERBERG, 2018). Já os sorotipos Ia e V são comumente isolados em casos de doença invasivas em adultos não-gestantes (SHABAYEK;…”