Thermostability and Alcohol Solubility of Vi Antigen

Abstract

Saline supernatants, saline heated extracts and alcoholic extracts of Vi Typhoid strains (Bhatnagar, Watson, Ty 2) and Salmonella ballerup were prepd. and tested for the presence of Vi antigen. The 3 prepns. of any one strain varied greatly in their properties particularly in the concn. of Vi antigen. Saline supernatants showed complete inhibition of Vi agglutination in dilutions of 4 to 8, heating from 60C to 100C markedly reduced the Vi content and filtering through a Seitz or Berkefeld completely removed it. Saline heated extracts gave complete inhibition in dilutions of 32 to 64, resisted 100C for 3 hrs. and produced Vi antiserums with titers as high as 2,560. They could be filtered though some loss in Vi content usually occurred. Alcoholic extracts showed complete inhibition in dilutions as high as 512, were thermostable, filtered without loss and have produced pure Vi antiserum with titers as high as 20,480. The apparent destruction of the Vi antigen at 60C is considered to be rather a release of the antigen from the cell into the menstruum.