IMMUNOLOGICAL ANALYSIS OF EXTRACELLULAR PRODUCTS AND CELL-SURFACE COMPONENTS OF MOTILE AEROMONAS ISOLATED FROM FISH

The present work describes the characterization of antigens present in the extracellular products (ECP) and cell wall of strains of motile A eromonas isolated from rainbow trout culture systems. The relationship s among virulence for fish, O-serogroup and profile of LPS were also e xamined. The slide agglutination test showed that most of the virulent strains of motile Aeromonas (72%) were included in the serotypes O3, O6, O11 and O19 (Guinee and Jansen System). However, there were also n on-pathogenic strains within these groups. Electrophoretic analysis of lipopolysaccharides (LPS) and proteins from cell envelope and ECP sho wed heterogeneity not only among the different serogroups but also wit hin the same serotype. Immunoblot assays of cell envelope components, and of LPS present in the ECP demonstrated a close relationship among Aeromonas strains from the same serotype, while strains from different serotypes were not immunologically related. Moreover, this assay show ed that motile Aeromonas belonging to distinct serotypes produced extr acellular proteins immunologically related. On the other hand, antigen ic cross reactivity was observed between the LPS obtained from cell en velope and those obtained from the ECP. The present results point out the need to include strains representative of each of the serotypes wh ich predominates in a particular area and their ECPs in the formation of vaccines against motile Aeromonas septicaemia.