Unveiling the virulence, genetic links, and enzyme profiles of bivalve-associated Vibrio parahaemolyticus from the southwest coast of India.

The study investigated the virulence, enzymatic activity, and genetic variants of Vibrio parahaemolyticus isolates from bivalves. Isolates were screened for the tdh, trh, T3SS1, T3SS2 (α and β), and T6SS1 genes associated with human infections. The tdh was found in 2.6% of isolates and trh in 3.5%. None carried both tdh and trh, and no isolates harbored T3SS2α or T3SS2β genes. All isolates contained T3SS1 genes, and 64% expressed T6SS1. Enzyme profiling revealed significant lipase, gelatinase, amylase, cellulase, lecithinase, DNase, and caseinase production, implying their ability to function as virulence factors by helping pathogens invade tissues, damage cells, and evade the host's immune defenses, thereby promoting disease development. Additionally, pulsed field gel electrophoresis and ERIC-PCR analyses examined genetic variability and linkages among the isolates. These findings demonstrate the genetic and enzymatic heterogeneity of V. parahaemolyticus in bivalves, underscoring potential risks to human health.