Insertional Mutants of Chlamydia caviae Display Altered Virulence

Abstract

The genus Chlamydia encompasses multiple bacterial species capable of colonizing and causing infection in a diverse range of host organisms. The type III secretion system and secreted effector proteins of this genus are important subjects for elucidating chlamydial biology. One important group of secreted proteins is the Inc family which are integral membrane proteins of the chlamydial inclusion found in all Chlamydia. Another novel protein, SinC, is a type III secreted effector initially described in Chlamydia psittaci, a zoonotic pathogen, but whose role in pathogenesis remains largely unknown. Characterization of specific genes in Chlamydia has been uniquely difficult due to its genetic intractability, but recent advances in chlamydial genetics have provided us the opportunity to generate targeted, stable mutants. The Chlamydia caviae GPIC strain has been used to model ocular and genital tract infection in guinea pigs. However recent C. caviae isolates were implicated in zoonotic respiratory infection in humans. The GPIC strain carries the two genes of interest, sinC and incA. Unlike for C. psittaci, we were able to perform mutagenesis in C. caviae without the constraints of BSL-3 containment, and with the benefit of well-characterized animal models. Here I engineered site-specific insertional mutations in sinC and incA, the first instances of targeted mutagenesis in the C. caviae lineage, with the aim of investigating the role of these genes in chlamydial pathogenesis.