RESUMO
The duck hepatitis B surface antigen(DHBsAg)particles were purified from the s-era of ducks by sucrose rate zonal and KBr isopycnic centrifugation.Analysis of DH-BsAg by SDS-PAGE revealed the major polypeptide to be 18Kd.The anti-DHBsAg-serum was made by immunizing cavy or rabbit and the anti-DHBsA-IgG was purifiedby DEAE-Sephadex A50.A simple,specific and sensitive Reverse Passive Hemgglutin-ation Assay for DHBsAg have been established with the method of Glutaraldehyde T-wo-step Procedure.The sera of ducks from three districts determined by RPHA andelectromicroscopy showed that the geographic distribution of DHBV is uneven and thearea of higher incidence of hepatitis B is also that of duck DHBV infection.So.therewould be other environmental facts influencing the uneven distribution of DHBV,andprobably that of HBV.