Immunoelectron Microscopy of Chlamydia psittaci with Monoclonal Antibodies

Abstract

An immunoelectron microscopic study was performed to determine the distribution of antigenic components on particles of Chlamydia psittaci and infected. cells using a number of monoclonal antibodies (MAbs). Of three anti-lipopolysaccharide (LPS) antibodies (4D5, A2 and 4G5), two antibodies (4D5 and A2) reacted with the surface of reticulate bodies (RBs) but not with that of elementary bodies (EBs). The other antibody (4G5) reacted with both EBs and RBs. Examination of infected cells in thin sections revealed that 4D5 and A2 combined with the membranes of both EBs and RBs. These results indicate that each LPS epitope localized at a different position in the chlamydial membrane. Most MAbs directed to protein antigens reacted on the surface of both EBs and RBs though 3E9 specific for the 90 kDa and 50 kDa protein components combined with RBs only.

Neutralization of Chlamydia psittaci with Monoclonal Antibodies

“…The properties of MAbs used are described in Table 1 and in our previous studies (2,19,21,22 contrast, one strain-specific MAb against 90 kDa protein (2B5) showed a different pattern of complement requirement and almost 80% of the IFU was reduced with the MAb alone at a higher concentration (1:160), although neutralization was much more efficient with complement (Fig. lb).…”

“…In fact, all of the MAbs to MOMP reacted with the epitopes on the surface of P-1041 EBs as revealed by immunoelectron microscopy regardless of their neutralizing activity. Of 2 anti-LPS MAbs, 4G5 showed neutralizing characteristics and also recognized surface-exposed epitopes (2). The other neutralizing MAbs (3B5 and 2B5 directed at 90/50 kDa and 90 kDa proteins) also reacted on the surface of the chlamydial particle.…”

“…In this study, we examined the neutralization of C. psittaci avian strain in vitro using MAbs of which the characteristics were well documented in our previous studies (2,19,21,22).…”