How GBS Got Its Hump: Genomic Analysis of Group B Streptococcus from Camels Identifies Host Restriction as well as Mobile Genetic Elements Shared across Hosts and Pathogens

Abstract

Group B Streptococcus (GBS) literature largely focuses on humans and neonatal disease, but GBS also affects numerous animals, with significant impacts on health and productivity. Spill-over events occur between humans and animals and may be followed by amplification and evolutionary adaptation in the new niche, including changes in the core or accessory genome content. Here, we describe GBS from one-humped camels (Camelus dromedarius), a relatively poorly studied GBS host of increasing importance for food security in arid regions. Genomic analysis shows that virtually all GBS from camels in East Africa belong to a monophyletic clade, sublineage (SL)609. Capsular types IV and VI, including a new variant of type IV, were over-represented compared to other host species. Two genomic islands with signatures of mobile elements contained most camel-associated genes, including genes for metal and carbohydrate utilisation. Lactose fermentation genes were associated with milk isolates, albeit at lower prevalence in camel than bovine GBS. The presence of a phage with high identity to Streptococcus pneumoniae and Streptococcus suis suggests lateral gene transfer between GBS and bacterial species that have not been described in camels. The evolution of camel GBS appears to combine host restriction with the sharing of accessory genome content across pathogen and host species.

Revisiting typing systems for group BStreptococcus(GBS) prophages: an application in prophage detection and classification in GBS isolates from Argentina

“…The prevalence of GBS isolates carrying at least one prophage and the average number of prophages per isolate found in our dataset correlates with previous reports on prophage content in GBS [11,13,15,35,36]. Our results also aligned with the integrase type and CC associations reported previously by Crestani [16].…”

“…GBS carriage of prophages associated to those from other streptococcal species causing infections in humans and animals has been extensively documented in the literature [11,15,35,48,49]. Our results further show that prophages detected in GBS isolates from Argentina are globally distributed and suggest that prophages belonging to groups A, B, and Further experimental work is needed in order to confirm the prophage transfer between streptococcal species, receptor specificity (tail proteins) and the restriction of C, D, and E prophages to GBS only.…”