HIGH-LEVEL EXPRESSION OF CHLAMYDIA-PSITTACI MAJOR OUTER-MEMBRANE PROTEIN IN COS CELLS AND IN SKELETAL-MUSCLES OF TURKEYS

The omp1 genes encoding the major outer membrane proteins (MOMPs) of a vian Chlamydia psittaci serovar A and D strains were cloned and sequen ced, The nucleotide sequences of the avian C. psittaci serovar A and D MOMP genes were found to be 98.9 and 87.8% identical, respectively, t o that of the avian C. psittaci serovar A strain 6BC, 84.6 and 99.8% i dentical to that of the avian C. psittaci serovar D strain NJ1, 79.1 a nd 81.1% identical to that of the C. psittaci guinea pig inclusion con junctivitis strain, 60.9 and 62.5% identical to that of the Chlamydia trachomatis L2 strain, and 57.5 and 60.4% identical to that of the Chl amydia pneumoniae IOL-207 strain, The serovar A or D MOMPs were cloned in the mammalian expression plasmid pcDNA1. When pcDNA1/MOMP A or pcD NA1/MOMP D was introduced into COS7 cells, a 40-kDa protein that was i dentical in size, antigenicity, and electrophoretic mobility to native MOMP was produced. Recombinant MOMP (rMOMP) was located in the cytopl asm of transfected COS7 cells as well as in the plasma membrane and wa s immunoaccessible. Intramuscular administration of pcDNA1/MOMP in spe cific-pathogen-free turkeys resulted in local expression of rMOMP in i ts native conformation, after which anti-MOMP antibodies appeared in t he serum.