Expression of two novel proteins in Chlamydia trachomatis during natural infection

Genes for a putative membrane associated protein (mvi-homologue) and a 48 k Da protein (ctr48) in Chlamydia trachomatis were characterized. The mvi-hom ologue has 12 transmembrane domains and shows considerable homology to the members of this gene family in various organisms. The ctr48 has a leader se quence 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. trachom atis. Immediately downstream from the ctr48 gene are multiple stop codons w hich are followed by a functional rho-independent terminator. The mvi-homol ogue and ctr48 genes are independently transcribed, albeit poorly in seroty pe B. However, protein products corresponding to these genes could not be d etected by western blotting in HEp2 cells infected with C. trachomatis. Nev ertheless, antibodies to peptides corresponding to these proteins were dete cted in sera with high micro-immunofluorescence titre against C. trachomati c, collected from a Chlamydia-endemic population. These results suggest tha t the mvi-homologue and ctr48 are expressed by C. trachomatis during natura l infection. (C) 2000 Academic Press.