Tolle T K, Glebe D, Linder M, Linder D, Schmitt S, Geyer R, Gerlich W H
Institute of Medical Virology, Clinicum and Medical School of Justus-Liebig-University, Giessen, Germany.
J Virol. 1998 Dec;72(12):9978-85. doi: 10.1128/JVI.72.12.9978-9985.1998.
Woodchucks chronically infected with woodchuck hepatitis virus (WHV) are a valuable model for human hepatitis B virus (HBV) in studies of pathogenesis, immunity, and antiviral therapy. For this reason, substantial efforts to characterize both the similarities and the differences between HBV and WHV are being made. The structure of the WHV surface proteins (WHs proteins) has not yet been adequately elucidated. The bands that would be expected for glycosylated and nonglycosylated small (S) WHs protein are found by sodium dodecyl sulfate gel electrophoresis of purified WHs protein, but the bands corresponding to the middle (M) and large (L) WHs proteins of HBV are not seen at the expected sizes, even though the sequences of the WHV and HBV surface protein genes are 60% homologous. By amino-terminal sequencing we have identified two bands at 41 and 45 kDa as the MWHs proteins, 8 kDa larger than expected. We have also confirmed that two bands at 24 and 27 kDa are SWHs proteins. A protein of 49 kDa was blocked at the N terminus, which using immunoblotting with an antiserum against WHV pre-S1 (positions 126 to 146) was identified, together with a part of the 45-kDa protein, as glycosylated and nonglycosylated LWHs protein of the expected size. Sialidase and O-glycosidase digestion showed that the larger size of MWHs protein results from the presence of O glycoside groups which are probably in the pre-S2 domain of MWHs protein. Since the pre-S2 domains of HBV and WHV have similar numbers of potential O glycosylation sites, it appears to be likely that the glycosyltransferases act differently on the viral proteins in woodchucks and humans.
慢性感染土拨鼠肝炎病毒（WHV）的土拨鼠是研究人类乙型肝炎病毒（HBV）发病机制、免疫和抗病毒治疗的宝贵模型。因此，人们正在做出大量努力来表征HBV和WHV之间的异同。WHV表面蛋白（WHs蛋白）的结构尚未得到充分阐明。通过对纯化的WHs蛋白进行十二烷基硫酸钠凝胶电泳，可发现糖基化和非糖基化的小（S）WHs蛋白预期出现的条带，但即使WHV和HBV表面蛋白基因序列有60%的同源性，对应于HBV中（M）和大（L）WHs蛋白的条带也未在预期大小出现。通过氨基末端测序，我们已确定41 kDa和45 kDa处的两条带为MWHs蛋白，比预期大8 kDa。我们还证实24 kDa和27 kDa处的两条带为SWHs蛋白。一个49 kDa的蛋白在N端被封闭，使用抗WHV前S1（第126至146位）抗血清进行免疫印迹分析，该蛋白与45 kDa蛋白的一部分一起被鉴定为预期大小的糖基化和非糖基化LWHs蛋白。唾液酸酶和O-糖苷酶消化表明，MWHs蛋白较大的尺寸是由O糖苷基团的存在导致的，这些基团可能位于MWHs蛋白的前S2结构域。由于HBV和WHV的前S2结构域具有相似数量的潜在O糖基化位点，看来糖基转移酶对土拨鼠和人类的病毒蛋白作用方式不同。
