Abstract
BackgroundAvian hepatitis E virus (HEV) infection is common in chicken flocks in China, as currently no measures exist to prevent the spread of the disease. In this study, we analyzed the effect of caged versus cage-free housing arrangements on avian HEV transmission. First, 127 serum and 110 clinical fecal samples were collected from 4 chicken flocks including the two arrangements in Shaanxi Province, China and tested for HEV antibodies and/or virus. Concurrently, 36 specific-pathogen-free chickens were divided equally into four experimental living arrangement groups, designated cage-free (Inoculated), caged (Inoculated), cage-free (Negative) and caged (Negative) groups. In caged groups, three cages contained 3 chickens each. Three chickens each from cage-free (Inoculated) and caged (Inoculated) groups (one chicken of each cage) were inoculated by cutaneous ulnar vein with the same dose of avian HEV, respectively. The cage-free (Negative) and caged (Negative) groups served as negative control. Serum and fecal samples were collected at 1 to 7 weeks post-inoculation (wpi) and liver lesions were scored at 7 wpi.ResultsThe results of serology showed that the avian HEV infection rate (54.10%) of the cage-free chickens was significantly higher than the one (12.12%) for caged chickens (P < 0.05). Also, the rate of detection of avian HEV RNA in the clinical fecal samples was significantly higher in the cage-free (22.80%, 13/57) than caged birds (5.66%, 3/53). Moreover, under experimental conditions, the infected number of uninoculated cage-free chickens (6) was significantly higher than the one for the uninoculated caged birds (2), as evidenced by seroconversion, fecal virus shedding, viremia and gross and microscopic liver lesions.ConclusionsThese results suggest that reduction of contact with feces as seen in the caged arrangement of housing chickens can reduce avian HEV transmission. This study provides insights for prevention and control of avian HEV infection in chicken flocks.
Highlights
Avian hepatitis E virus (HEV) infection is common in chicken flocks in China, as currently no measures exist to prevent the spread of the disease
The results showed that the 16 sequences shared high identity (82%–99%) with other known avian HEV strains from GenBank, indicating the 16 fecal samples contained avian HEV RNA
The positive rates for antibodies (32.28%) and viral RNA (14.55%) suggest that avian HEV infection is common in these 4 flocks from Shaanxi Province, which aligns with HEV detection rates in other provinces in China [16]
Summary
Avian hepatitis E virus (HEV) infection is common in chicken flocks in China, as currently no measures exist to prevent the spread of the disease. 127 serum and 110 clinical fecal samples were collected from 4 chicken flocks including the two arrangements in Shaanxi Province, China and tested for HEV antibodies and/or virus. The cage-free (Negative) and caged (Negative) groups served as negative control. In China in 2010, an avian HEV strain infecting a broiler breeder chicken flock exhibiting hepatitis-splenomegaly syndrome was isolated and characterized [11]. Blocking fecal-oral transmission should prevent the spread of virus infection [22], especially since this route has been shown to be the main avian HEV transmission route in chicken flocks [1, 7, 8]. We evaluated the efficacy of disease control through inhibition of chicken contact with feces
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