Expression of two novel proteins in Chlamydia trachomatis during natural infection.

Genes for a putative membrane associated protein (mvi -homologue) and a 48 kDa protein (ctr48) in Chlamydia trachomatis were characterized. The mvi -homologue has 12 transmembrane domains and shows considerable homology to the members of this gene family in various organisms. The ctr48 has a leader sequence and the C-proximal half is tryptophan-rich. The latter region shares 65% identity with the N-proxima third of C. pneumoniae 76 kDa protein over an overlap of 231 amino acid residues. The genes for the mvi -homologue and the ctr48 are present in the B, Ba, D, E, J and L2 serotypes of C. trachomatis. Immediately downstream from the ctr48 gene are multiple stop codons which are followed by a functional rho-independent terminator. The mvi -homologue and ctr48 genes are independently transcribed, albeit poorly in serotype B. However, protein products corresponding to these genes could not be detected by western blotting in HEp2 cells infected with C. trachomatis. Nevertheless, antibodies to peptides corresponding to these proteins were detected in sera with high micro-immunofluorescence titre against C. trachoImatic, collected from a Chlamydia -endemic population. These results suggest that the mvi -homologue and ctr48 are expressed by C. trachomatis during natural infection.

Serological evidence of the three chlamydial species in an aboriginal community in the Northern Territory.

OBJECTIVE: To determine the pattern of seropositivity to the three species of Chlamydia in women and children from a single community. DESIGN: Testing of blood samples obtained during a prospective study of mothers and infants. For each individual, the sample giving the highest titre of antichlamydial antibody was included in the analysis. SETTING: The only health centre for a small rural community in the Top End of the Northern Territory. This served all 1200 or so residents, almost 95% of whom were Aboriginal. PARTICIPANTS: Sixty-one pregnant Aboriginal women at routine antenatal clinic visits, and 114 of their children aged between one and six years at the time of sampling. MAIN OUTCOME MEASURE: Specific IgG or IgM antibody to any of the three species of Chlamydia at titres > or = 32, as determined by micro-immunofluorescence. RESULTS: IgG antibody to one or more chlamydial species was found in 83.6% of mothers and 42.1% of their children. IgM antibody was found in five mothers and four children, in each case against only one chlamydial species. IgG antibody to C. trachomatis was found in 55.7% of mothers and 28.9% of children, to C. pneumoniae in 59.0% of mothers and 19.3% of children, and to C. psittaci in 29.5% of mothers and 17.5% of children. Log linear modelling gave positive correlations between seropositivity for C. trachomatis and C. pneumoniae (chi 2 = 9, P < 0.01), and for C. trachomatis and C. psittaci (chi 2 = 15, P < 0.001). Cross-reactivity was more evident in children than in mothers. CONCLUSIONS: This is the first Australian report providing serological evidence of exposure to the three chlamydial species in one community. The seropositivity patterns suggest complex interactions when all species are present.