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Sixty five isolates of Vibrio harveyi were subjected to random amplified polymorphic DNA (RAPD)-PCR analysis and protein profiling to investigate the genetic variability among V. harveyi prevalent along the coast and also assess the discriminating ability of these two molecular methods. A total of 10 RAPD primers were assayed for their specificity in detecting V. harveyi, of which only two primers: PM3 and CRA25 were highly reproducible and found suitable for use in RAPD-PCR. The genetic diversity among V. harveyi isolates assessed by RAPD-PCR using PM3 primer yielded 35 different RAPD patterns which clustered the isolates into 15 groups at 72% similarity level. Similarly, RAPD-PCR with CRA25 clustered the 38 patterns into 10 groups at 74% similarity. The discriminatory index (D) value calculated for RAPD fingerprints generated with PM3 and CRA25 were 0.90 and 0.85, respectively. On the other hand, molecular typing of V. harveyi using whole cell proteins generated profiles that showed no major difference indicating the technique to be not useful in typing strains of this bacterium. However, a few of the isolates showed the presence of unique band of 28 kDa that needs to be further investigated to understand the role of the protein in disease process if any.

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The levels of haemagglutinins in Penaeus monodon, following administration of immunostimulants, β‐glucans and/or vibrio bacterin either orally or by immersion, were studied. The freshly drawn haemolymph was incubated with microbial materials like β‐glucans/vibrio bacterin and serum obtained after coagulation was administered to naïve animals. The immunostimulant treatments either via immersion, feeding or injection were found to cause an increase (P<0.006) in haemagglutination activity (HA) of the haemolymph against mouse erythrocytes. Injection of saline or heterologous haemolymph caused an increase in the HA, but injection of haemolymph serum obtained by clotting haemolymph in the presence of vibrio bacterin or glucan did not bring about an increase in HA. There was no change in the haemolymph protein profile of the groups receiving immunostimulants through immersion or feed. Two protein bands (27 and 30 kDa), which were present in the uninjected group, were found to be overexpressed in the haemolymph‐injected groups. Three bands of 17, 21 and 23 kDa, which were absent in control or saline‐injected groups, were present in all the haemolymph serum‐injected groups. The study indicates that modulation of HA may partly account for the immunomodulatory activity of immunostimulants like β‐glucan or vibrio bacterins.

Aims:  Evaluation of protein profiling for typing Vibrio parahaemolyticus using 71 strains isolated from different seafood and comparison with other molecular typing techniques such as random amplified polymorphic DNA analysis (RAPD) and enterobacterial repetitive intergenic consensus sequence (ERIC)‐PCR. Methods and Results:  Three molecular typing methods were used for the typing of 71 V. parahaemolyticus isolates from seafood. RAPD had a discriminatory index (DI) of 0·95, while ERIC‐PCR showed a DI of 0·94. Though protein profiling had less discriminatory power, use of this method can be helpful in identifying new proteins which might have a role in establishment in the host or virulence of the organism. Conclusions:  The use of protein profiling in combination with other established typing methods such as RAPD and ERIC‐PCR generates useful information in the case of V. parahaemolyticus associated with seafood. Significance and Impact of the Study:  The study demonstrates the usefulness of nucleic acid and protein‐based studies in understanding the relationship between various isolates from seafood.