Noma K, Kiyotani K, Kouchi H, Fujii Y, Egi Y, Tanaka K, Yoshida T
Department of Bacteriology, School of Medicine, Hiroshima University, Japan.
Arch Virol. 1998;143(10):1893-909. doi: 10.1007/s007050050428.
Multi-cycle replication and plaque formation of influenza A and B viruses and cleavage activation of their hemagglutinin (HA) by an endogenous protease(s) were examined in two MDCK cell lines, MDCK(-) and MDCK(+). No exogenous trypsin was required for multi-cycle replication and plaque formation of all the influenza A viruses tested in the MDCK(+) cell, while those of the viruses in the MDCK(-) cell were completely trypsin-dependent. In both cell lines, on the other hand, influenza B viruses grew well in the absence of trypsin. The capability of multiple replication and plaque formation of the influenza viruses correlated with cleavage of the HA precursor (HA0) to HA1 and HA2, indicating that both cell lines express an HA activating endoprotease(s); that of the MDCK(+) cell activates the HA of influenza A and B viruses, and that of the MDCK(-) cell does only the HA of influenza B virus. Furthermore, the protease of the MDCK(+) cell was strongly suggested to be present on the cell surface and a serine protease. The MDCK(+) cell would be useful for isolation of influenza viruses from clinical specimens and for screening of protease inhibitors for anti-influenza virus drugs.
在两种MDCK细胞系MDCK(-)和MDCK(+)中检测了甲型和乙型流感病毒的多轮复制和蚀斑形成，以及它们的血凝素(HA)被内源性蛋白酶切割激活的情况。在MDCK(+)细胞中，所检测的所有甲型流感病毒的多轮复制和蚀斑形成均不需要外源胰蛋白酶，而MDCK(-)细胞中的病毒复制和蚀斑形成则完全依赖胰蛋白酶。另一方面，在两种细胞系中，乙型流感病毒在无胰蛋白酶的情况下生长良好。流感病毒的多轮复制和蚀斑形成能力与HA前体(HA0)切割为HA1和HA2相关，这表明两种细胞系均表达一种HA激活内蛋白酶；MDCK(+)细胞的内蛋白酶可激活甲型和乙型流感病毒的HA，而MDCK(-)细胞的内蛋白酶仅激活乙型流感病毒的HA。此外，强烈提示MDCK(+)细胞的蛋白酶存在于细胞表面，且为丝氨酸蛋白酶。MDCK(+)细胞将有助于从临床标本中分离流感病毒，并用于筛选抗流感病毒药物的蛋白酶抑制剂。
