NEUTRALIZATION OF CHLAMYDIA-PSITTACI WITH MONOCLONAL-ANTIBODIES

Neutralization of Chlamydia (C.) psittaci avian strain P-1041 was exam ined in vitro using monoclonal antibodies (MAbs). Of the 10 MAbs used, 6 were found to exhibit neutralizing capability. These include 3 agai nst major outer membrane protein (MOMP), 1 against lipopolysaccharide (LPS) and 2 against other protein molecules [90 kilodalton (kDa) and 9 0/50 kDa]. Most neutralizing MAbs were dependent on complement for eff icient neutralization, while a strain-specific MAb (2B5) against the 9 0 kDa protein displayed a different requirement for complement and neu tralized the infectivity of the P-1041 at high concentrations without complement. By competitive inhibition enzyme-linked immunosorbent assa y (competitive inhibition ELISA), all 3 neutralizing anti-MOMP MAbs we re demonstrated to recognize different epitopes found in very close pr oximity to each other on the outer membrane.