Characteristics of vhvp-2 gene distribution and diversity within the Vibrio causing translucent post-larvae disease (TPD).

Translucent post-larva vibriosis (V) in Penaeus vannamei, caused by the virulence factor Vibrio high virulent protein 2 (vhvp-2) gene, poses a significant threat to the shrimp aquaculture industry in China. This study conducted a comprehensive analysis of the vhvp-2 gene distribution and genetic diversity among Vibrio, which play a key role in the pathogenesis of translucent post-larvae disease (TPD). A total of 6281 Vibrio genomes from the NCBI database were screened, revealing the presence of the vhvp-2 gene in 26 strains, predominantly in V. parahaemolyticus, with diverse locations on both plasmids and chromosomes. Comparative analysis of the genomes, plasmids, and the vhvp-2 gene successfully differentiated three distinct clusters of Vibrio species and identified at least two major plasmid groups. However, these plasmid groups did not exhibit the same evolutionary relationships as the host bacteria themselves. The analysis also revealed the conserved presence of the vhvp-2 gene along with genetic variations. Moreover, the widespread presence of antimicrobial resistance genes (ARGs) and virulence factors in Vibrio strains enhances their pathogenicity and poses increased public health risks. The findings underscore the importance of understanding the adaptability, evolution, and ecological characteristics of Vibrio strains harboring vhvp-2 gene. This research provides a scientific foundation for the development of effective disease prevention and control strategies, contributing to the mitigation of TPD's impact on the shrimp aquaculture industry and supporting its sustainable and healthy growth.