Antityphoid Activity of Vi Antigen from Extra-Generic Sources

Abstract

When mice were immunized with serial dilutions of Eberthella lyphosa and Escherichia coli 5396/38 vaccines and then given 50-1000 MLD of typical Vi strains of E. typhosa, the E. coli vaccine provided a significantly greater immunity. Expts. indicate that this superiority is a manifestation of a greater amt. of Vi antigen on the V-form E. coli than on the V-form typhoid bacilli. The immunogen was easily removed from the organisms by soln. in dilute HC1. The V-form of E. coli 5396/38 is a good source of the antityphoid Vi extract.