Cold Spring Harbor Lab
p204, 1989.Department of Microbiology, Shanghai Medical University, Shanghai, 20032, China
A system for assaying interferon (IFN) production in ducks was established. Peripheral blood leukocytes and spleen cells were isolated from ducks and induced with either NDV or a synthetic double stranded RNA (dsRNA). INF was assayed by CPE inhibition test on primary duck embryo fibroblasts. No IFN was detected in serum of DHBV DNA positive ducks. Leukocytes of DHBV infected ducks showed decreased production of IFN when induced with dsRNA (IFN titer: log2 CPEI50 5.80 in DHBV infected ducks: 7.81 in controls, p<0.05). Hepatocytes were isolated from one-week-old ducklings by liver perfusion. When stained with antiserum against duck albumin, more than 95% cells were positive. DHBV (3 x 106 in 30 microliters) and NDV (100HAU in 0.2ml) were used as inducers. Hepatocytes produced IFN induced by NDV at a titer of 5.92+-0.61, while no IFN induced by DHBV. When DHBV and NDV were simultaneously used as inducers, the titer of IFN dropped to 3.95+-0.57 (p<0.001). This study indicates that DHBV can neither induce leukocytes, nor hepatocytes to produce IFN. Furthermore, the inhibitory role of DHBV on IFN production may be important in DHBV persistence in hepatocytes