Entry of DNA viruses into cells and establishment of infection

动物DNA病毒感染细胞的早期阶段，即病毒粒子附着在细胞表面、病毒粒子进入细胞、病毒粒子向细胞核运输和病毒粒子进入细胞核等过程的机制仍不清楚，尽管这些过程对于病毒感染的建立是必不可少的。为了更好地了解病毒感染的这些方面，我们研究了影响建立猴病毒40(SV40)感染效率的因素。我们发现一些细胞成分在病毒感染的建立中起着至关重要的作用。病毒粒子纯化后，SV40粗品中的平面形成活性和T抗原合成活性明显降低。纯化的病毒粒子与猴子CV-1细胞的提取物孵育后，活性完全恢复。猴子CV-1细胞是生产感染SV40的宿主细胞。该活性来源于磷脂o…的功能。更多的CV-1细胞。构建的由磷脂组成的脂质体与病毒粒子并排结合。这种结合提高了病毒粒子对宿主细胞的吸附效率。电子显微镜显示，吸附在细胞上的病毒粒子通过内吞作用内化。然后，我们研究了细胞质结构和功能的抑制物对感染的建立的影响。结果表明，微管的功能是病毒粒子向细胞核运输所必需的，而微丝和溶酶体的功能不是建立感染所必需的。在本研究过程中，很快发现，由于无法获得用于检测病毒早期蛋白的抗体，对了解其他DNA病毒感染早期机制的研究受到阻碍。为了制备抗体，我们合成了两个来源于12型腺病毒(AD12)E1a基因DNA序列的多肽。我们正在用抗AD12多肽的抗血清和单抗研究AD12感染细胞的早期阶段。较少

The mechanism of the early phase of infection of a cell with animal DNA viruses, i.e., attachment of virions to cell surface, virion's penetration into the cell, transportation of virions towards the cell nucleus, and virion's entry into the nucleus, remains still unclear, although these events are indispensable for the establishment of viral infection. To better understand these aspects of viral infection, we examined factors affecting the efficiency of establishment of infection with simian virus 40 (SV40). We found that some cellular components play essential roles for the establishment of viral infection.Plaque-forming activity and T-antigen synthesizing activity in the crude preparation of SV40 markedly decreased after the purification of virions. A full restoration of the activity occurred after the incubation of the purified virions with the extract of monkey CV-1 cells, host cells for productive infection with sV40. this activity was derived from the function of phospholipids o … More f CV-1 cells. The constructed liposomes composed of the phospholipids became associated with virions on side-to-side. This association enhanced the efficiency of adsorption of the virions to host cells. Electron microscopy revealed that virions adsorbed to cells were internalized by endocytosis. We then examined the effects of inhibitors of the cytoplasmic structures and functions on the establishment of infection. Results indicate that the function of microtubules is required for the transportation of virions towards the cell nucleus, and that the function of microfilaments and lysosomes is not required for the establishment of infection.During the course of the present study, it soon became clear that studies to understand the mechanism of the early phase of infection with other DNA viruses are hindered by the unavailability of antibodies useful for detection of the immediate early proteins of the viruses. To prepare antibodies for this purpose, we synthesized two peptides derived from the DNA sequence of the E1A gene of adenovirus type 12 (Ad12). We are now investigating the early phase of infection of cells with Ad12 by using antisera and monoclonal antibodies against these peptides. Less