Prevalence of infectious hypodermal and hematopoietic necrosis virus (IHHNV) in wild adult blue shrimp Penaeus stylirostris from the Northern Gulf of California, Mexico

Conventional histopathology and molecular methods, including dot blot hybridization with a specific DNA probe and polymerase chain reaction (PCR), were used to assess the prevalence and degree of severity of infectious hypodermal and hematopoietic necrosis virus (IHHNV) infection in wild adult blue shrimp Penaeus stylirostris captured in the Northern Gulf of California. Through histopathological analysis, a presumptive diagnosis of IHHNV was initially determined by demonstrating the presence of Cowdry type A inclusion bodies. Prevalence rate ranged from 80% to 100% in females and was 60% in males. Using the dot blot technique, the results showed that the presence of IHHNV varied in females from 86% to 89% and in males from 56% to 57%. Results were further validated using PCR to assess the prevalence of IHHNV in eggs and sperm. The PCR results showed that IHHNV prevalence in unfertilized eggs was 100% and in sperm was 60%. We concluded that wild adults of P. stylirostris are infected with IHHNV but that they do not show clinical signs of disease. Our data suggest that in the 10th year of the IHHNV epizootic in the Gulf of California, a host-pathogen relationship might have reached a putative equilibrium.