Identification and characterization of a porcine parvovirus nonstructural polypeptide
Identification and characterization of a porcine parvovirus nonstructural polypeptide
复制标题
猪细小病毒非结构多肽的鉴定和表征
作者：
T. Molitor;H. Joo;M. Collett
猪细小病毒(PPV)感染的猪胎儿的血清除了A和B病毒结构蛋白外，还免疫沉淀和84-86千道尔顿的多肽。这种多肽命名为NS-1，存在于PPV感染的细胞裂解物中，但不存在于纯化的病毒粒子中。部分蛋白水解图显示，NS-1与A、B病毒结构蛋白无关。感染细胞中的三种蛋白均在丝氨酸残基上被磷酸化，NS-1还含有磷酸苏氨酸。从32PI或[35S]蛋氨酸的脉冲标记实验中发现，NS-1在感染后5~7h首次出现，而病毒结构多肽则在感染后9~11h首次合成。脉冲追逐实验表明，NS-1最初以84千道尔顿蛋白质的形式出现，随后被结构修饰为较慢的电泳迁移率形式。病毒感染后NS-1出现的时间与病毒DNA合成的起始时间一致，提示该多肽(及其修饰形式)可能参与了PPV的复制。
Sera from porcine parvovirus (PPV)-infected swine fetuses immunoprecipitated and 84- to 86-kilodalton polypeptide in addition to the A and B virion structural proteins. This polypeptide, designated NS-1, was present in PPV-infected cell lysates but not in purified virions. Partial proteolysis mapping revealed that NS-1 was not related to the A and B viral structural proteins. All three proteins in infected cells were phosphorylated at serine residues, and NS-1 also contained phosphothreonine. From pulse-labeling experiments with either 32Pi or [35S]methionine, NS-1 was found to first appear 5 to 7 h postinfection, whereas the viral structural polypeptides were first synthesized 9 to 11 h postinfection. Pulse-chase experiments revealed that NS-1 initially appeared as an 84-kilodalton protein and was subsequently structurally modified to forms of slower electrophoretic mobilities. The time of appearance of NS-1 after virus infection coincided with the initiation of viral DNA synthesis, suggesting that this polypeptide (and the modified forms thereof) may be involved in PPV replication.