Prevalence of different outer membrane proteins in isolates of Aeromonas species

Outer membrane proteins (Omps) are located at host-bacterial interface and are important for host immune responses and as targets for drug therapy. In the present study, outer membrane protein profiling of 40 isolates of Aeromonas spp. (A. hydrophila, A. trota, A. caviae, A. veronii biovar sobria, A. jandaei and A. schubertii) obtained from different sources was done using SDS-PAGE, PCR and Western blotting techniques. The 3-4 high intensity bands at the region of 25-45 kDa were obtained in all the isolates with minor differences. Twenty Omp patterns (M1-M20) were obtained. The isolates were further tested for omp specific PCR and Omp specific antibody based Western blot. Positive reaction was obtained in 35 isolates of Aeromonas using ompTS-PCR and anti-OmpTS antibodies based Western blot. Primers specific for omp48 and antibodies to Omp48 reacted with 32 isolates. One mutant of A. hydrophila (AB-3-5-2 mutant) and 4 clinical isolates (one A. jandaei and three A. schubertii) were negative for both the genes. When both the assay systems were tested with bacterial cultures other than Aeromonas spp., anti-OmpTS antibodies were specific for Aeromonas spp. whereas, the anti-omp48 antibodies gave reaction with Escherichia coli and other Gram negative non-aeromonads. From the results we conclude the usefulness of OmpTS for identification of virulent Aeromonas spp. and Omp48 as a potential recombinant vaccine candidate for Gram negative opportunistic infection of fish. Omp profiling can be a useful molecular marker for characterizing Aeromonas isolates.