Cowley J A, Gorman B M
Queensland Institute of Medical Research, Bramston Terrace, Herston, Qld, Australia.
Vet Microbiol. 1990 Apr;22(2-3):137-52. doi: 10.1016/0378-1135(90)90101-z.
The effects on virus infectivity, haemagglutinating (HA) activity and polypeptide composition of bluetongue virus type 20 (BTV 20) were determined after digestion with the proteolytic enzymes, chymotrypsin, thermolysin and trypsin. Virus infectivity increased eight to 50-fold after exposure periods which reflected the activity of the proteases. Identical maximum increases in HA activity (i.e. 4096, 1024 and 128 HAU per 0.05 ml with sheep, bovine and human erythrocytes, respectively) occurred with each of the three proteases. Peak increases in virus infectivities and HA activities occurred after similar exposure periods. Outer capsid protein VP2 was the most sensitive virus protein to proteolytic digestion, being cleaved into a number of smaller polypeptides that remained attached to the virus particle. Digestion with chymotrypsin and thermolysin yielded four common cleavage products, designated P93, P76, P54 and P25 according to their estimated molecular weight, which suggested that they shared at least three cleavage sites. VP2 cleavage products resulting from digestion with trypsin differed somewhat from those of chymotrypsin and thermolysin, although the generation of polypeptides P93, P54 and P25.5 suggested the existence of common cleavage sites for the three proteases. Possible mechanisms whereby proteolytic cleavage of VP2 may enhance the infectivity and HA activity of BTV 20 are discussed.
在用蛋白水解酶胰凝乳蛋白酶、嗜热菌蛋白酶和胰蛋白酶消化后，测定了20型蓝舌病病毒（BTV 20）对病毒感染性、血凝（HA）活性和多肽组成的影响。在反映蛋白酶活性的暴露期后，病毒感染性增加了8至50倍。三种蛋白酶中的每一种都使HA活性出现相同的最大增加（即分别用绵羊、牛和人红细胞时，每0.05 ml为4096、1024和128个血凝单位）。病毒感染性和HA活性的峰值增加发生在相似的暴露期后。外衣壳蛋白VP2是对蛋白水解消化最敏感的病毒蛋白，被切割成许多仍附着在病毒颗粒上的较小多肽。用胰凝乳蛋白酶和嗜热菌蛋白酶消化产生了四种常见的切割产物，根据其估计分子量分别命名为P93、P76、P54和P25，这表明它们至少共享三个切割位点。胰蛋白酶消化产生的VP2切割产物与胰凝乳蛋白酶和嗜热菌蛋白酶的产物略有不同，尽管多肽P93、P54和P25.5的产生表明三种蛋白酶存在共同的切割位点。讨论了VP2的蛋白水解切割可能增强BTV 20感染性和HA活性的可能机制。
