Ohtsuka N, Yamada Y K, Taguchi F
National Institute of Neuroscience, NCNP, Tokyo, Japan.
J Gen Virol. 1996 Aug;77 ( Pt 8):1683-92. doi: 10.1099/0022-1317-77-8-1683.
The receptor proteins, MHVR1 (Bgp C or splice variant of mmCGM1 containing two ectodomains) and MHVR2 (mmCGM2) have been reported to be functional receptors for MHV, although there was a significant difference in their virus-binding activity as determined by virus overlay protein blot assay (VOPBA). To compare the receptor function of these proteins, their virus-binding capacities were tested by using soluble forms of the proteins which lacked the transmembrane and intracytoplasmic domains. To estimate the amounts of these proteins expressed, an epitope of influenza HA protein, for which specific monoclonal antibody was available, was used as a tag. Recombinant soluble MHVR1 and MHVR2, expressed in RK 13 cells using recombinant vaccinia virus were secreted into the culture fluids of infected cells expressing these proteins. The inhibitory effect on virus infectivity of MHVR1 was shown to be about 500-fold higher than that of MHVR2. A similar disparity was observed in virus binding by VOPBA. These two proteins worked as functional receptors when they were expressed on resistant BHK-21 cells. However, the efficiency of MHV infection in BHK-21 cells expressing MHVR1 was about 30-fold higher, as compared with those expressing MHVR2. These data show that the receptor function of MHVR1 was significantly higher than that of MHVR2 and suggests that the difference in susceptibility between SJL and BALB/c mice might be due to the specific receptor protein expressed in those animals.
据报道，受体蛋白MHVR1（Bgp C或包含两个胞外结构域的mmCGM1的剪接变体）和MHVR2（mmCGM2）是小鼠肝炎病毒（MHV）的功能性受体，尽管通过病毒覆盖蛋白印迹分析（VOPBA）测定，它们的病毒结合活性存在显著差异。为了比较这些蛋白的受体功能，使用缺乏跨膜和胞质结构域的可溶性蛋白形式来测试它们的病毒结合能力。为了估计这些蛋白的表达量，使用流感血凝素（HA）蛋白的一个表位作为标签，针对该表位有特异性单克隆抗体。利用重组痘苗病毒在RK 13细胞中表达的重组可溶性MHVR1和MHVR2被分泌到表达这些蛋白的感染细胞的培养液中。结果显示，MHVR1对病毒感染性的抑制作用比MHVR2高约500倍。通过VOPBA在病毒结合方面也观察到了类似的差异。当这两种蛋白在抗性BHK - 21细胞上表达时，它们都起到了功能性受体的作用。然而，与表达MHVR2的细胞相比，在表达MHVR1的BHK - 21细胞中，MHV感染效率高约30倍。这些数据表明，MHVR1的受体功能显著高于MHVR2，并提示SJL和BALB/c小鼠之间易感性的差异可能是由于这些动物中表达的特异性受体蛋白所致。
