[Membrane component of Shigella flexneri and their relationship to bacteria antigenicity and virulence]

Our previous works have shown that membrane proteins of S. flexneri can elicit protection against the bacteria in vivo. In this study, we further, using human convalescent sera (HCS) from adult patients infected with S. flexneri, investigated the relationship between membrane components of S. flexneri and their antigenicities and virulences. It was shown in immunoblotting that 5 virulent strains of S. flexneri and avirulent strain T32 derived from S. flexneri 2a by Istrati in Romania and used as a live vaccine, had three common proteins bands formed by the components of MW 67 kD, 63 kD and 60 kD with either HCS from patients infected with S. flexneri 2a and 3a or HCS absorbed by an avirulent variant strain 24570 of S. flexneri 2a, while virulent strains M90T and M25-8A (pWR110)minI shown another two bands of Mw 78 kD and 35 kD respectively. In contrast, no band was found with strain 24570. HCS from patients infected with S. flexneri 1a, 2a and 3a as well as those HCS absorbed by 24570 had blocking effect on the invasiveness of virulent strain of S. flexneri to the kerato conjunctiva of guinea pigs; nevertheless, HCS absorbed by T32 lost the blocking effect accompanied by disappearance of 67 kD, 63 kD and 60 kD components when T32 was used as antigen indicating that 67 kD, 63 kD and 60 kD membrane components of S. flexneri may account for the antigen of S. flexneri eliciting protection antibodies in vivo.(ABSTRACT TRUNCATED AT 250 WORDS)