Antibody-neutralizing activity against all urogenital Chlamydia trachomatis serovars in Chlamydia suis-infected pigs

Abstract

It is known that neutralizing species-specific or serovar-specific antibodies are produced in response to chlamydial infection in humans and in some animal species. In a previous study, a strong in vitro neutralizing activity to Chlamydia suis in 80% of sera from C. suis-infected pigs had been observed. In view of the close relationship between C. suis and Chlamydia trachomatis, in the present study, the neutralizing activity against D-K C. trachomatis and C. suis purified elementary bodies (EBs) in sera collected from C. trachomatis-infected patients and C. suis-infected pigs was evaluated. A neutralizing activity of 50-70% was observed in the human sera against the homologous serovar and one to five heterologous C. trachomatis serovars. These sera were also able to neutralize C. suis EBs. The pig sera showed a strong neutralizing activity (70-100%) against C. suis EBs and all eight urogenital C. trachomatis serovars. These results suggested the presence of common immunogenic antigens in C. trachomatis and C. suis. Immunoblot analysis, performed to elucidate the target of this neutralizing activity, showed a clear reactivity in human and pig sera against two proteins of 150 and 40 kDa MW, when tested either with C. trachomatis or with C. suis EBs.

Rare Events of Intragenus and Intraspecies Horizontal Transfer of the 16S rRNA Gene

“…There was a 40-kb fragment present in the genome of C. trachomatis RC Fs 342 that was absent in the genome of C. trachomatis RC J 943 (close relative containing two identical ribosomal RNA gene operons). The inserted DNA fragment included an foreign rRNA gene operon (97.3% 16S rRNA gene identity to other copies) with a flanking fragment that was homologous to C. suis (in this comparison: Strain MD56, which is the only strain of C. suis with genome sequence available, 98.8% 16S rRNA gene identity to C. trachomatis RC Fs 342) and a genomic island with high GC content (56.1% in comparison to the average whole-genome GC content of 41.5%) from C. suis strain R19 ( Donati et al 2011 ) (AY428550, 99.9% identity over 13 kb). The genomic island contained a terminal transposase (the only transposase gene found throughout the genome), which may facilitate HGT of the genomic island containing tetracycline resistance genes enhancing the virulence of C. suis R19 ( Donati et al 2011 ).…”

“…The inserted DNA fragment included an foreign rRNA gene operon (97.3% 16S rRNA gene identity to other copies) with a flanking fragment that was homologous to C. suis (in this comparison: Strain MD56, which is the only strain of C. suis with genome sequence available, 98.8% 16S rRNA gene identity to C. trachomatis RC Fs 342) and a genomic island with high GC content (56.1% in comparison to the average whole-genome GC content of 41.5%) from C. suis strain R19 ( Donati et al 2011 ) (AY428550, 99.9% identity over 13 kb). The genomic island contained a terminal transposase (the only transposase gene found throughout the genome), which may facilitate HGT of the genomic island containing tetracycline resistance genes enhancing the virulence of C. suis R19 ( Donati et al 2011 ). The four strains of C. trachomatis (J 6276tet1, RC Fs 342, RC Fs 852, and RC Js 122) were found to possess the same transferred rRNA operon and shared the same genomic organization in the region of the transferred rRNA operon ( supplementary fig.…”

Evidence for Chlamydia in Crohns Disease

“…suis is closely related to Chlamydia trachomatis [7,8]. The thought that the latter might be responsible for Crohn's disease had been examined earlier.…”