Pugh J C, Sninsky J J, Summers J W, Schaeffer E
J Virol. 1987 May;61(5):1384-90. doi: 10.1128/JVI.61.5.1384-1390.1987.
DNA from the pre-S region of the duck hepatitis B virus (DHBV) genome was inserted into an open reading frame vector designed to give high-level expression in Escherichia coli. The resulting fusion protein contained the first 8 amino acids of beta-galactosidase, 86 amino acids of the DHBV pre-S region, and 219 amino acids of chloramphenicol acetyltransferase at the C terminus (beta-gal:pre-S:CAT). Rabbit antiserum against purified beta-gal:pre-S:CAT was used to identify pre-S-containing polypeptides in DHBV particles by Western blotting. A dominant species of 36 kilodaltons (kDa) was identified. Antiserum against the major 17-kDa DHBsAg polypeptide also reacted with the 36-kDa protein. This suggests that the DHBV envelope gene polypeptides share the same carboxyl terminus, but differ in the sites from which translation is initiated. N-linked carbohydrate was not detected on either the 17- or 36-kDa envelope proteins. Anti-beta-gal:pre-S:CAT abolished infectivity of the virus in an in vitro assay. Thus, the pre-S region is exposed on the surfaces of infectious virions and may be directly involved in binding of virus to host-cell receptors.
将鸭乙型肝炎病毒（DHBV）基因组前S区的DNA插入一个开放阅读框载体，该载体设计用于在大肠杆菌中实现高水平表达。所得融合蛋白包含β-半乳糖苷酶的前8个氨基酸、DHBV前S区的86个氨基酸以及位于C端的219个氯霉素乙酰转移酶氨基酸（β-半乳糖苷酶：前S区：氯霉素乙酰转移酶）。用针对纯化的β-半乳糖苷酶：前S区：氯霉素乙酰转移酶的兔抗血清通过蛋白质印迹法鉴定DHBV颗粒中含前S区的多肽。鉴定出一种主要的36千道尔顿（kDa）蛋白。针对主要的17-kDa DHBsAg多肽的抗血清也与36-kDa蛋白发生反应。这表明DHBV包膜基因多肽具有相同的羧基末端，但翻译起始位点不同。在17-kDa或36-kDa包膜蛋白上均未检测到N-连接的碳水化合物。在体外试验中，抗β-半乳糖苷酶：前S区：氯霉素乙酰转移酶抗体消除了病毒的感染性。因此，前S区暴露于感染性病毒粒子的表面，可能直接参与病毒与宿主细胞受体的结合。
