Pérez L, Carrasco L
Centro de Biología Molecular Severo Ochoa (CSIC-AUM), Universidad Autónoma de Madrid, Canto Blanco, Spain.
J Gen Virol. 1994 Oct;75 ( Pt 10):2595-606. doi: 10.1099/0022-1317-75-10-2595.
Semliki Forest virus (SFV) enters cells by receptor-mediated endocytosis, followed by acidification of endosomes by the action of the vacuolar H(+)-ATPase. Fusion of the viral and the endosomal membrane delivers the viral genome to the cytoplasm. Direct blockade of the vacuolar H(+)-ATPase by the selective inhibitor bafilomycin A1 (BFLA1) prevented the infection of cells by SFV, if the compound was present during the first minutes of infection. Attachment and penetration of virus particles were not the targets of the antibiotic. BFLA1 and the ionophore monensin potently blocked SFV infection even at low pH, indicating that acidic pH is not sufficient for SFV to deliver its genome to the cytoplasm, but the proper functioning of the H(+)-ATPase pump is necessary. Other enveloped RNA-containing viruses, such as vesicular stomatitis virus or influenza virus were also blocked by BFLA1, whereas no effect was observed with Sendai virus, which enters into cells by direct fusion with the plasma membrane. Enveloped DNA-containing viruses, such as herpes-viruses and vaccinia virus, infected the cells even when the vacuolar H(+)-ATPase was inhibited by BFLA1; similar behaviour was observed with poliovirus and adenovirus. Animal virus particles promote the internalization of proteins and other macromolecules during entry. BFLA1 blocked co-entry of the toxin alpha-sarcin when induced by SFV, but not when induced by Sendai virus. The inhibition of the enzyme responsible for acidification of endosomes by means of the potent inhibitor BFLA1 constitutes a selective and powerful tool to analyse the low-pH dependent mechanism(s) during virus entry and will aid in understanding the mechanisms and routes of entry of animal viruses into cells.
塞姆利基森林病毒（SFV）通过受体介导的内吞作用进入细胞，随后液泡H(+)-ATP酶作用使内体酸化。病毒膜与内体膜融合将病毒基因组递送至细胞质。如果在感染的最初几分钟内存在选择性抑制剂巴弗洛霉素A1（BFLA1），它对液泡H(+)-ATP酶的直接阻断可防止SFV感染细胞。病毒颗粒的附着和穿透不是该抗生素的作用靶点。即使在低pH值下，BFLA1和离子载体莫能菌素也能有效阻断SFV感染，这表明酸性pH值不足以使SFV将其基因组递送至细胞质，但H(+)-ATP酶泵的正常功能是必需的。其他含包膜的RNA病毒，如水泡性口炎病毒或流感病毒，也被BFLA1阻断，而通过与质膜直接融合进入细胞的仙台病毒则未受影响。含包膜的DNA病毒，如疱疹病毒和痘苗病毒，即使液泡H(+)-ATP酶被BFLA1抑制仍能感染细胞；脊髓灰质炎病毒和腺病毒也表现出类似行为。动物病毒颗粒在进入过程中促进蛋白质和其他大分子的内化。BFLA1可阻断SFV诱导的毒素α-肌动蛋白共内化，但不能阻断仙台病毒诱导的共内化。通过强效抑制剂BFLA1抑制负责内体酸化的酶，构成了一种分析病毒进入过程中低pH依赖性机制的选择性且强大的工具，将有助于理解动物病毒进入细胞的机制和途径。
