Kooi C, Mizzen L, Alderson C, Daya M, Anderson R
Department of Microbiology and Infectious Diseases, University of Calgary Health Sciences Centre, Alberta, Canada.
J Gen Virol. 1988 Jun;69 ( Pt 6):1125-35. doi: 10.1099/0022-1317-69-6-1125.
Three categories of cell lines are described which differ with respect to their permissiveness to mouse hepatitis virus (MHV), strain A59. Fully permissive L-2 cells gave rise to 100- to 1000-fold higher numbers of infectious centres than did semi-permissive LM, LM-K or C-1300 cells, whereas non-permissive Vero or C-6 cells were refractory to MHV infection. On an infected cell basis, semi-permissive cells (LM, LM-K or C-1300) were as efficient in replicating viral RNA, protein and progeny virions as fully permissive L-2 cells. This result suggested that LM, LM-K and C-1300 cells were deficient in their ability to permit full expression (as compared to L-2 cells) of an early event in MHV infection. Assays of radiolabelled MHV binding to cells of all three categories (L-2, LM, LM-K and C-6) and of infectious MHV binding to L-2 and LM-K cells showed no correlation between virion binding and degree of permissiveness to MHV infection. Internalization of MHV virions into L-2 and LM-K cells, as assayed by proteinase K-resistant infectious centres, showed that, in both cases, maximum virion uptake was complete by approximately 40 min post-inoculation. Direct assays of infectious virion uptake showed similar numbers of internalized viruses (only a threefold difference between L-2 and LM-K cells, as compared to a 500-fold difference in infectious centres). Attempts to enhance MHV uptake into LM-K cells relative to L-2 cells, with DEAE-dextran or the cytoskeleton-disrupting drugs colchicine and cytochalasin B, were unsuccessful, further suggesting that the ability of LM-K cells to internalize the virus was not lacking. The results suggest that MHV infection of at least some semi-permissive cells, such as the LM-K line, is limited by a process which chronologically correlates with virion uncoating. Since LM-K cells have been shown previously to be resistant to membrane fusion in MHV infection, it is postulated that they may also restrict uncoating of MHV by limiting the degree of normal endosomal membrane fusion with the viral envelope.
本文描述了三类细胞系，它们对A59株小鼠肝炎病毒（MHV）的易感性有所不同。完全易感的L - 2细胞产生的感染中心数量比半易感的LM、LM - K或C - 1300细胞高出100至1000倍，而非易感的Vero或C - 6细胞对MHV感染具有抗性。以感染细胞为基础，半易感细胞（LM、LM - K或C - 1300）在复制病毒RNA、蛋白质和子代病毒体方面与完全易感的L - 2细胞效率相同。这一结果表明，与L - 2细胞相比，LM、LM - K和C - 1300细胞在允许MHV感染早期事件充分表达的能力上存在缺陷。对放射性标记的MHV与所有三类细胞（L - 2、LM、LM - K和C - 6）的结合以及感染性MHV与L - 2和LM - K细胞的结合进行检测，结果显示病毒体结合与对MHV感染的易感性程度之间没有相关性。通过蛋白酶K抗性感染中心检测MHV病毒体进入L - 2和LM - K细胞的情况，结果表明，在两种情况下，接种后约40分钟病毒体摄取量达到最大。对感染性病毒体摄取的直接检测显示内化病毒数量相似（L - 2和LM - K细胞之间仅相差三倍，而感染中心相差500倍）。尝试用DEAE - 葡聚糖或破坏细胞骨架的药物秋水仙碱和细胞松弛素B增强LM - K细胞相对于L - 2细胞对MHV的摄取，但未成功，这进一步表明LM - K细胞内化病毒的能力并不缺乏。结果表明，至少一些半易感细胞（如LM - K系）的MHV感染受到一个与病毒体脱壳在时间上相关的过程的限制。由于先前已证明LM - K细胞在MHV感染中对膜融合具有抗性，因此推测它们也可能通过限制正常内体膜与病毒包膜的融合程度来限制MHV的脱壳。
