A collection of swine, fish, and cetacean Erysipelothrix rhusiopathiae strains representing 16 serotypes was analyzed for possession of the three currently recognized surface protective antigen (spa)-types: spaA, spaB, and spaC. Polymerase chain reaction (PCR) assays and Western blotting with a SpaA-specific monoclonal antibody demonstrated that spa-type is not confined to specific serotype groups. In particular, the spa-type of strains of aquatic origin was more variable than those of terrestrial origin, and possessed the distinct ability to express more than one spa. In a cross-protection study, mice immunized with an E. rhusiopathiae serotype 2 SpaA-type strain and challenged with various E. rhusiopathiae isolates were completely protected against strains exhibiting a single homologous spa, but variably protected against strains possessing a heterologous spa or those harboring more than one spa-type. RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted. Keywords: Erysipelothrix rhusiopathiae Surface protective antigen Erysipelas a b s t r a c t A collection of swine, fish, and cetacean Erysipelothrix rhusiopathiae strains representing 16 serotypes was analyzed for possession of the three currently recognized surface protective antigen (spa)-types: spaA, spaB, and spaC. Polymerase chain reaction (PCR) assays and Western blotting with a SpaA-specific monoclonal antibody demonstrated that spa-type is not confined to specific serotype groups. In particular, the spa-type of strains of aquatic origin was more variable than those of terrestrial origin, and possessed the distinct ability to express more than one spa. In a cross-protection study, mice immunized with an E. rhusiopathiae serotype 2 SpaA-type strain and challenged with various E. rhusiopathiae isolates were completely protected against strains exhibiting a single homologous spa, but variably protected against strains possessing a heterologous spa or those harboring more than one spa-type.Published by Elsevier Ltd.

A rapid test method was developed for detecting mycoplasma contamination in veterinary biological products. The method reduces testing time by 2 weeks and shows comparable sensitivity to the current agar-based detection model. The primary goals for the development of the test were to reduce the testing time, incorporate a method that was easily adaptable across the veterinary biologics industry and reduce the subjective interpretation of results. We found that biological enrichment is necessary to maintain sensitivity of the detection method when compared to the standard culture-based test and that periodic sampling of enrichment cultures is essential to detect a wide variety of mycoplasma species that may be present as contaminants. The PCR detection method is comparable to the agar-based model and can reduce the overall testing time by up to 14 days.

A collection of Erysipelothrix rhusiopathiae swine, fish, and cetacean strains representing nearly all 16 serotypes was analyzed for possession of the surface protective antigen (spa) family of genes and their expression products. Polymerase chain reaction (PCR) assays utilizing primers specific for spaA, spaB and spaC revealed that spa-type is not absolutely associated with serotype when two strains of serotypes previously reported to possess spaB produced amplicons with spaA-specific primers. These results were supported when a monoclonal antibody, specific for the protective domain of SpaA, reacted strongly in Western blotting with a 65 kilodalton (kDa) protein from both strains. Vaccination challenge studies were conducted in mice to evaluate an E. rhusiopathiae bacterin composed of a serotype 2 SpaA-type swine strain in its ability to protect mice against challenge with virulent fish and cetacean strains of various spa-types. Vaccinated mice were completely protected against challenge strains possessing spaA but variably protected against challenge strains possessing heterologous spa or more than one spatype.