<prompt> Agglutination with O antigen of S. typhi is inhibited by :-Vi AgFlagellerF antigenAll the above  <response>: Agglutination with O antigen of S. typhi is inhibited by Vi antigen. Vi antigen: Surface polysaccharide envelope or capsular antigen covering the O antigen. Prevents its agglutination with O antiserum. Phage typing of S. typhi can be done by using Vi specific bacteriophages. Used for vaccination. 