Shioda T, Wakao S, Suzu S, Shibuta H
Department of Viral Infection, University of Tokyo, Japan.
Virology. 1988 Feb;162(2):388-96. doi: 10.1016/0042-6822(88)90479-5.
By determining gene nucleotide sequences we compared the primary structures of the membrane (M), fusion (F), and hemagglutinin-neuraminidase (HN) proteins of bovine parainfluenza 3 virus strains, M, SC, and MR which are substrains derived from a wild strain YN. The M and SC viruses are indistinguishable in having very weak hemagglutination (HA) and neuraminidase (NA) activities, but M virus' syncytium-inducing (SI) activity is considerably higher than that of the SC virus. However, the results showed that the amino acid sequence of the F protein was identical in M and SC viruses, demonstrating that M virus' high SI activity was not due to alteration of its F protein. Two differences in M and SC viruses' other proteins then seemed to be important, although their significance in the SI activity is not clear at present; the first being the 70th amino acid residue of the M protein, which was Asp in the M virus and Gly in the SC virus, and the other being the 539th residue of the HN protein, which was Tyr in the M virus and His in the SC virus. The nucleocapsid proteins of both M and SC viruses were identical. The MR virus, which is a variant derived from the M virus and has high HA and NA activities but very weak SI activity, was different from the M virus at only one site throughout the M, F, and HN proteins; the 193rd amino acid residue of the HN protein was Leu in the MR virus and Phe in the M virus. This result strongly suggested that the substitution of Leu with Phe at this particular site was closely linked to the drastic reduction in both HA and NA activities.
通过测定基因核苷酸序列，我们比较了牛副流感3病毒株M、SC和MR的膜（M）蛋白、融合（F）蛋白和血凝素神经氨酸酶（HN）蛋白的一级结构，M、SC和MR是源自野生株YN的亚株。M病毒和SC病毒在血凝（HA）和神经氨酸酶（NA）活性非常弱这一点上难以区分，但M病毒的合胞体诱导（SI）活性明显高于SC病毒。然而，结果表明，M病毒和SC病毒的F蛋白氨基酸序列相同，这表明M病毒的高SI活性并非由于其F蛋白的改变。那么，M病毒和SC病毒其他蛋白中的两个差异似乎很重要，尽管它们在SI活性中的意义目前尚不清楚；第一个差异是M蛋白的第70个氨基酸残基，在M病毒中是天冬氨酸（Asp），在SC病毒中是甘氨酸（Gly），另一个差异是HN蛋白的第539个残基，在M病毒中是酪氨酸（Tyr），在SC病毒中是组氨酸（His）。M病毒和SC病毒的核衣壳蛋白是相同的。MR病毒是源自M病毒的一个变种，具有高HA和NA活性，但SI活性非常弱，在整个M、F和HN蛋白中，MR病毒与M病毒仅在一个位点不同；HN蛋白的第193个氨基酸残基在MR病毒中是亮氨酸（Leu），在M病毒中是苯丙氨酸（Phe）。这一结果有力地表明，在这个特定位点亮氨酸被苯丙氨酸取代与HA和NA活性的急剧降低密切相关。
