Lack of allelic polymorphism for the major outer membrane protein gene of the agent of guinea pig inclusion conjunctivitis (Chlamydia psittaci).

The major outer membrane protein gene (omp1) was sequenced for each of six Chlamydia psittaci (guinea pig inclusion conjunctivitis GPIC]) strains isolated from guinea pigs. Five of the isolates were obtained in the United States during the 1960s and 1970s, including the prototype strain isolated by Murray in 1962. The other isolate was obtained from a guinea pig in England. The nucleotide sequence of the omp1 gene for each strain was identical. The lack of omp1 allelic polymorphism among GPIC isolates suggests that, unlike C. trachomatis, the GPIC agent lacks antigenic variation in the major outer membrane protein.