A 28 KDA MAJOR IMMUNOGEN OF CHLAMYDIA-PSITTACI SHARES IDENTITY WITH MIP PROTEINS OF LEGIONELLA SPP AND CHLAMYDIA-TRACHOMATIS - CLONING AND CHARACTERIZATION OF THE CHLAMYDIA-PSITTACI MIP-LIKE GENE

Chlamydia psittaci strain guinea-pig inclusion conjunctivitis (GPIC) p roduces a self-limiting ocular infection of guinea-pigs, and this cond ition is a representative animal model of ocular chlamydial disease. C onvalescent guinea-pigs, which are resistant to reinfection, produce a ntibodies to several elementary-body proteins, including an uncharacte rized antigen of 28 kDa. Convalescent guinea-pig sera were used to ide ntify, from a lambda expression library, two overlapping GPIC genomic clones that produced the 28 kDa antigenic protein, Nucleotide sequence analysis revealed that the gene coding for the 28 kDa protein was sim ilar to the mip (macrophage infectivity potentiator) genes from Legion ella pneumophila and Chlamydia trachomatis, The GPIC gene and its prod uct were accordingly designated mip and Mip, respectively. Analysis of the regions flanking mip identified three tightly linked open reading frames coding for predicted products with sequence similarity to aspa ragine tRNA ligase (AspS), rRNA methylase (SpoU), and thioredoxin (Trx A), The arrangement of these genes in GPIC was aspS-mip-spoU-trxA, Seq uence analysis of PCR products produced using genomic DNA from an ovin e abortion strain of C. psittaci and from C. trachomatis strain LGV-43 4 demonstrated that the arrangement of mip, spoU and trxA is common am ong these chlamydiae.