Immunological Response of the Rabbit to Vi Antigen

Abstract

Vi antibody response of rabbits varied depending on whether Vi antigen was administered in particulate or soluble state. Vi antigen in particulate form induced hemagglutinins, bacterial agglutinins, and passive cutaneous anaphylaxis (PCA) antibodies, whereas soluble Vi antigen induced only hemagglutinins. Guinea pigs passively sensitized with antisera against particulate Vi antigen gave PCA reactions when challenged with either soluble or cellular Vi antigen; antisera against soluble Vi antigen were negative for PCA. The specificity of PCA was demonstrated by its dependence on the Vi concentration and by absorption of PCA activity from antisera with V-form cells of Salmonella typhosa .

Vaccines and cell-mediated immunity

“…In the peritoneal cavity of the vaccinated mouse, anti-Vi antibodies do play an important protective role (128,263). However, the validity of the intraperitoneally infected mouse as a model of human typhoid fever has been disputed by a number of workers (88,193) and at present, evidence for a protective role for Vi antigen in human typhoid fever vaccines is not strong (43). However, despite this caveat, claims for increased protection following the use of acetone-killed vaccines continue to appear in the literature (15,126), although a careful examination also reveals a number of reports that heated phenol-killed suspensions can be just as protective (61,69,82,113).…”

Comparative immunogenicities of Vi polysaccharide-protein conjugates composed of cholera toxin or its B subunit as a carrier bound to high- or lower-molecular-weight Vi

“…The Vi, a linear homopolymer of -4-D-cL-NAcGalpA-(1--*, has T-independent properties similar to those of other capsular polysaccharides; i.e., reinjection did not elicit a booster response in animals or in humans (9,10,19,21,28,31,34,38).…”

Agar Plaque Formation by Mouse Spleen Cells in Response to Vaccination with Vi Antigen and Typhoid Vaccines

“…earlier study, by production of Vi-hemagglutinins in NIH mice after immunization with vaccine 6A or Vi antigen (1,2). Vi-containing S. typhosa organisms were resistant to killing by immune spleen cells in the presence of complement even when the cells were producing Vi antibody.…”