The high-quality draft genomes of two Vibrio parahaemolyticus strains, one that causes the acute hepatopancreatic necrosis disease (AHPND) in cultured shrimps (FIM-S1708 ⁺ ), and another that does not (FIM-S1392 ⁻ ) are reported. A chromosome-scale assembly for the FIM-S1392 ⁻ genome is reported here. The analysis of the two genomes gives some clues regarding the genomic differences between the strains.

High evaporation rates due to solar intensity and low precipitation could represent a challenging culture environment in northwestern Mexico, generating osmotic stress in shrimp due to high salinity. Bacterial infections by pathogenic Vibrio strains are highly virulent in shrimp culture. This study evaluated betaine aldehyde dehydrogenase (BADH) activity and glycine betaine (GB) levels in Litopenaeus vannamei under high salinity levels plus experimental infection with virulent Vibrio parahaemolyticus. At 35 ppt (control group) and 40 ppt after infection, GB levels increased two-fold in the gills except at 45 ppt and were significantly higher at 50 ppt. The highest GB levels were in the hepatopancreas of the uninfected group at 45 ppt. In the gills, BADH activity decreased after 2 h of exposure at 40 and 45 ppt; at 50 ppt, there was a significant increase in the uninfected groups. However, upon infection, activity increased at all salinities except 50 ppt. In the hepatopancreas of the uninfected groups, the highest activity was at 40 ppt and this was lowest at 50 ppt after 8 h. In the muscles, BADH was detectable at all salinities; infection caused an increase in its activity at 45 and 50 ppt. Despite sudden exposure to high salinity plus experimental infection, our results show that Litopenaeus vannamei does not inhibit BADH activity, allowing GB synthesis, which may play a role in shrimp survival under these conditions.