SPECIFICITY OF MONOCLONAL-ANTIBODIES ELICITED BY MUCOSAL INFECTION OFBALB C MICE WITH VIRULENT SHIGELLA-FLEXNERI 2A/

Protective immunity against shigellosis is thought to be determined by the O-antigen side chains of the lipopolysaccharide (LPS) molecule, T o study possible common protective epitopes, monoclonal antibodies rea cting with Shigella flexneri 2a LPS were generated from BALB/c mice in fected ocularly with the virulent serotype 2a strain S. flexneri 2457T and tested against a panel of S. flexneri LPSs by enzyme-linked immun osorbent and immunoblot assays, Four monoclonal antibodies were identi fied, all of which showed restricted specificity patterns. Three diffe rent patterns of reactivity to LPS possessing the 3,4 group antigen we re seen: (i) 2a only, (ii) 2a and 5a, and (iii) 2a, 4a, 5a, and Y. The se results have implications for designing a Shigella vaccine that wil l be protective against related serotypes. Electron microscopy studies showed that the monoclonal antibodies bind to the bacterial surface i n a patchy pattern, suggesting their potential use for examining the L PS distribution on the sun-face of the bacteria.