A Comparative Study On The Effects Of Various Protease Treatments Upon The Structure, Immunogenicity, And Infectivity Of The Elementary Bodies OF Chlamydia Trachomatis (Strains L2 And D) And Chlamydia Psittaci (Strain MN)

Abstract

The effects of several proteases upon the structure, immunogenicity, and infectivity of the elementary bodies (EBs) of Chlamydia trachomatis (strains L2 and D) and ot C. psittaci (strain MN) was studied. Four major proteases were studied and ot these, thermolysin and proteinase K were extremely etticient in cleaving the chlamydial major outer membrane protein (MOMP) while trypsin and chymotrypsin demonstrated cleavage abilities to a more limited extent in all strains. Proteinase K had the added ettect ot cleaving the surtace-exposed proteins on the chlamydial outer wall to the extent that monomeric MOMP was no longer detectable by immunoblot procedures with specitic antisera and even antigenic tragments were absent. The most interesting result noted was that while the MN strain was most resistant to cleavage by proteases in terms o-f structure, its infectivity was most drastically reduced by the treatment. The L2 strain, on the other hand, showed a subsequent increase in infectivity while the structure of its surface-exposed proteins was most drastically altered. It was also observed that trypsinized MN EBs had an increased ability to bind to eucaryotic cells while similarily treated L2 EBs had a decreased ability. These results together indicated that protease treatment of chlamydial elementary bodies tended to alter infectivity by mainly affecting rates of internalization into human epithelial cells rather than the extent to which these same EBs could bind to and associate with the epithelial cells. This work helps to support previous results indicating that surface-exposed protease sensitive domains of chlamydial proteins may play a role in the initial interacton chlamydiae with eucaryotic cells.