The pathogenicity of duck hepatitis A virus types 1 and 3 on ducklings

Duck hepatitis A virus (DHAV) is one of the pathogens that cause fatal duck viral hepatitis (DVH) in ducklings, which is an acute and contagious disease with a high mortality rate. Despite a continuing official duck vaccination program, DHAV infection remains a major threat to the duck industry. Considerable changes were observed in the epidemiology of DHAV-1/-3 in China over time. Therefore, comparing the pathogenicity of different DHAV serotypes can provide a theoretical basis for the diagnosis and prevention of DVH. In this study, we systematically investigated the effects of infection with DHAV-1/-3 field strains on clinical signs, gross lesions, histopathological changes, viral RNA detection, enzymatic systems, and metabolite concentrations. The results demonstrated that the major macroscopic and microscopic lesions in ducks infected with DHAV-1/-3 in the liver, brain, spleen, pancreas, and kidneys exhibited no significant differences. After 24 h of infection, DHAV quickly appeared in blood and major organs. Significant changes in clinical chemical markers together with histopathological lesions and viral RNA detection indicated that the liver is the major target organ for both viruses, resulting in impaired of liver integrity and function. In addition, we found that both viruses were able to invade both central and peripheral immune organs. Also lipase plasma activity was substantially affected by DHAV-1/-3, indicating that the integrity and function of the pancreas was compromised. However, there was no significant difference in pathogenicity between DHAV-1 and -3. The results of this study provide new insights into the pathogenesis of DHAV-1/3, two viruses that cause serious depression, metabolic disorders, and immunosuppression.