Yamamoto-Goshima F, Maeno K, Morishita T, Ueda M, Fujita Y, Nakajima K, Yoshii S
Laboratory of Virology, Research Institute for Disease Mechanism and Control, Nagoya University School of Medicine, Japan.
J Virol. 1994 Feb;68(2):1250-4. doi: 10.1128/JVI.68.2.1250-1254.1994.
When ts7, a temperature-sensitive (ts) mutant of influenza B/Kanagawa/73 virus, infected MDCK cells at the nonpermissive temperature (37.5 degrees C), infectious virus was produced at very low levels compared with the yield at the permissive temperature (32 degrees C) and hemagglutinating activity and enzymatic activity of neuraminidase (NA) were negligible. However, viral protein synthesis and transport of hemadsorption-active hemagglutinin to the cell surface were not affected. When the cell lysate was treated with bacterial NA, hemagglutinating activity was recovered but infectivity was not, even after further treatment with trypsin. It was found that ts7 was defective in transport of NA to the cell surface and formation of virus particles. Analysis of the genomes of non-ts recombinants obtained by crossing ts7 and UV-inactivated B/Lee showed that ts7 had the ts mutation only in RNA segment 6 coding for NA and the glycoprotein NB. Nucleotide sequence analysis of the RNA segment revealed that ts7 had four amino acid changes in the NA molecule but not in NB. We suggest that assembly or budding of influenza B virus requires the presence of NA at the plasma membrane, unlike influenza A virus.
当乙型流感病毒/神奈川/73株的温度敏感（ts）突变体ts7在非允许温度（37.5℃）下感染MDCK细胞时，与在允许温度（32℃）下的产量相比，产生的感染性病毒水平极低，神经氨酸酶（NA）的血凝活性和酶活性可忽略不计。然而，病毒蛋白合成以及具有血细胞吸附活性的血凝素向细胞表面的转运并未受到影响。当细胞裂解物用细菌NA处理时，即使在用胰蛋白酶进一步处理后，血凝活性得以恢复，但感染性并未恢复。发现ts7在将NA转运至细胞表面以及病毒粒子形成方面存在缺陷。通过ts7与紫外线灭活的B/Lee株杂交获得的非ts重组体的基因组分析表明，ts7仅在编码NA和糖蛋白NB的RNA片段6中存在ts突变。对该RNA片段的核苷酸序列分析显示，ts7在NA分子中有四个氨基酸变化，而在NB中没有。我们认为，与甲型流感病毒不同，乙型流感病毒的组装或出芽需要质膜上存在NA。
