Abstract
BackgroundFrom 2014 to 2015 in China, many broiler breeder and layer hen flocks exhibited a decrease in egg production and some chickens developed hepatitis syndrome including hepatomegaly, hepatic necrosis and hemorrhage. Avian hepatitis E virus (HEV) and avian leucosis virus subgroup J (ALV-J) both cause decreasing in egg production, hepatomegaly and hepatic hemorrhage in broiler breeder and layer hens. In the study, the seroprevalence of avian HEV and ALV-J in these flocks emerging the disease from Shandong and Shaanxi provinces were investigated.ResultsA total of 1995 serum samples were collected from 14 flocks with hepatitis syndrome in Shandong and Shaanxi provinces, China. Antibodies against avian HEV and ALV-J in these serum samples were detected using iELISAs. The seroprevalence of anti-avian HEV antibodies (35.09%) was significantly higher than that of anti-ALV-J antibodies (2.16%) (p = 0.00). Moreover, the 43 serum samples positive for anti-ALV-J antibodies were all also positive for anti-avian HEV antibodies. In a comparison of both provinces, Shandong chickens exhibited a significantly higher seroprevalence of anti-avian HEV antibodies (42.16%) than Shaanxi chickens (26%) (p = 0.00). In addition, the detection of avian HEV RNA and ALV-J cDNA in the liver samples from the flocks of two provinces also showed the same results of the seroprevalence.ConclusionsIn the present study, the results showed that avian HEV infection is widely prevalent and ALV-J infection is endemic in the flocks with hepatitis syndrome from Shandong and Shaanxi provinces of China. These results suggested that avian HEV infection may be the major cause of increased egg drop and hepatitis syndrome observed during the last 2 years in China. These results should be useful to guide development of prevention and control measures to control the diseases within chicken flocks in China.Electronic supplementary materialThe online version of this article (doi:10.1186/s12917-016-0892-4) contains supplementary material, which is available to authorized users.
Highlights
From 2014 to 2015 in China, many broiler breeder and layer hen flocks exhibited a decrease in egg production and some chickens developed hepatitis syndrome including hepatomegaly, hepatic necrosis and hemorrhage
Seroprevalence tests showed that avian hepatitis E virus (HEV) and avian leucosis virus subgroup J (ALV-J) infections have emerged among broiler and layer flocks in Shandong and Shaanxi provinces, explaining increased egg drop and hepatitis syndrome observed during the last 2 years
Because some flocks were almost free of ALV-J infection in the sampled areas, we could conclude that avian HEV infection was likely the major cause of the diseases observed among the flocks of broiler breeder and layer hens in China over the last 2 years
Summary
From 2014 to 2015 in China, many broiler breeder and layer hen flocks exhibited a decrease in egg production and some chickens developed hepatitis syndrome including hepatomegaly, hepatic necrosis and hemorrhage. Avian hepatitis E virus (HEV) and avian leucosis virus subgroup J (ALV-J) both cause decreasing in egg production, hepatomegaly and hepatic hemorrhage in broiler breeder and layer hens. From 2014 to 2015, many broiler breeder and layer hen flocks exhibited a decreasing in egg production in some areas of China. The disease mainly causes an increase in mortality, a decrease in egg production and hepatitis syndrome in broiler breeders and laying hens aged from 30 to 72 weeks [1]. When accompanied by a change in environment and feed or co-infection with other pathogens, subclinically infected flocks may develop big liver and spleen disease and manifest a decrease in egg production. Avian HEV was first characterized in China in 2010 in a report [7]
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