Unusual antigenic composition of an Arizona strain.

: The immunochemical analysis of Arizona strain 23:23:30:42 displayed a peculiar antigenic composition. Hyperimmune sera prepared in rabbits with formaldehyde-treated bacteria precipitated, in agar-gel, the proteins from numerous Salmonellae and E. coli by homogenous lines of apparent serological identity with the Arizona proteins. The reactions were unilateral. The proteins from Arizona did not react against the heterologous antibacterial sera tested; they precipitated, however against sera, rich in common antibodies, that were prepared with proteins from Salmonellae and E. coli. The genetic architecture of this Arizona's chromosome is, apparently, responsible for the unusual antigenic composition of the strain as exhibited by the immunochemical analysis of its hyperimmune serum.