Studies on Erysipelothrix insidiosa S. rhusiopathiae. 2. Serological study.

Sixty-two strains of E. insidiosa isolated from joints or regional lymph nodes of pigs with arthritis were examined for their antigenic characteristics. HCl and CHCOOH extracts were made from all strains and precipitation tests performed with these extracts and rabbit anti-sera for types A, A, B, B, C, D, E, and G. The type distribution of the strains was as follows: 1 belonged in type A, 46 in type B, while 15, which did not contain demonstrable acid-soluble antigen, were designated N strains. The 46 type B strains could be divided into 4 subtypes on the basis of the patterns of reaction between, on the one hand HCl and CHCOOH extracts, and, on the other hand, B and B sera. Thirty-two strains reacted with both B and B sera in CHCOOH extracts, but not in HCl extracts; these strains were referred to a new subtype, B. Nine strains, which reacted with B serum in HCl and CHCOOH extracts and with B serum in CHCOOH extracts only, were referred to subtype B. Four strains that reacted with B and B sera in both extracts were referred to subtype B. The only representative of the 4th subtype was an interesting strain which in previous studies had been shown to differ from the rest of the strains in other ways, too. This strain reacted with both B and B sera, but only in HCl extract.