<prompt> Proteus antigen cross react with:KlebsiellaChlamydiaeRickettsiaeE. coli  <response>: Ans. c i.e., RickettsiaeRef: Ananthanarayan, 9the, p. 410Proteus antigens OX19, OX2, OXK Strains cross reacts with group specific alkali stable lipopolysaccharide rickettsial antigens. The application of this property is done in the Weil Felix heterophile agglutination test. 