Expression by of type III secretion system components during infection
Résumé
Contact-dependent secretion systems, such as the type III secretion system (T3SS), have been shown to play significant roles in the pathogenicity of many Gram-negative bacterial pathogens. is a novel, obligate intracellular Gram-negative bacterium, which has been identified as the etiological agent of proliferative enteropathies in numerous animal species. Analysis of the genome sequence of the strain PHE/MN1-00 has revealed the presence of a T3SS secretion system in this bacterium. In this study we aimed to determine whether this important virulence mechanism is also present in our strain LR189/5/83. Using bacteria PCR-based approach, we verified the presence of a genomic region encoding a T3SS. Specifically, a gene highly homologous to the energiser component of the prototypic T3SS of spp. was identified and termed . Two further open reading frames (ORFs) contiguous with were also identified: and which are also homologues of ORFs within the T3SS of spp. To establish whether this T3SS may be functional, expression was monitored directly by RT-PCR and indirectly by detection of serological responses in vaccinated and infected animals. Transcripts for and were detected and purified rLscQ was recognized by antiserum from infected pigs, indicating expression during infection. By analogy to other bacteria, this T3SS may be crucial for intracellular development and is likely to play a significant role in the virulence of this unusual pathogen.
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