Calvert J G, Ogawa R, Yanagida N, Nazerian K
USDA Agricultural Research Service, Avian Disease and Oncology Laboratory, East Lansing, Michigan 48823.
Virology. 1992 Dec;191(2):783-92. doi: 10.1016/0042-6822(92)90254-m.
A fowlpox virus (FPV) gene with homology to the vaccinia virus p37K major envelope antigen gene was identified and sequenced. The predicted product has a molecular weight of 43,018 Da (p43K). The FPV p43K gene has 37.5% identity with its vaccinia counterpart and higher homology with a molluscum contagiosum virus gene (42.6% identity). Based on upstream sequences, p43K appears to be regulated as a late gene. Recombinant FPV were generated in which a large portion of p43K was replaced by the Escherichia coli lacZ gene. These recombinants failed to produce visible plaques under standard conditions. After prolonged incubation the microplaques developed into small macroscopic plaques. Plaques were purified on the basis of lacZ expression. Single-cycle growth curves comparing the p43K-deleted recombinant (designated fJd43Z) with parental FPV showed that the two viruses produce identical amounts of intracellular virions, but that fJd43Z released 20-fold fewer infectious particles into the medium. CsCl gradient centrifugation of [3H]thymidine-labeled virus was employed to examine differences in the production of physical particles. The two viruses produced equivalent levels of intracellular virions, but fJd43Z failed to produce detectable levels of released particles. FPV p43K is therefore involved in the release of virions from infected cells.
鉴定并测序了一种与痘苗病毒p37K主要包膜抗原基因具有同源性的禽痘病毒（FPV）基因。预测产物的分子量为43,018道尔顿（p43K）。FPV p43K基因与其痘苗病毒对应基因具有37.5%的同一性，与传染性软疣病毒基因具有更高的同源性（42.6%同一性）。根据上游序列，p43K似乎作为晚期基因受到调控。构建了重组FPV，其中p43K的大部分被大肠杆菌lacZ基因取代。这些重组体在标准条件下未能产生可见噬斑。长时间孵育后，微噬斑发展成小的宏观噬斑。根据lacZ表达对噬斑进行纯化。将缺失p43K的重组体（命名为fJd43Z）与亲本FPV的单循环生长曲线比较表明，两种病毒产生的细胞内病毒粒子数量相同，但fJd43Z释放到培养基中的感染性粒子减少了20倍。采用[3H]胸腺嘧啶核苷标记病毒的CsCl梯度离心法来检测物理粒子产生的差异。两种病毒产生的细胞内病毒粒子水平相当，但fJd43Z未能产生可检测水平的释放粒子。因此，FPV p43K参与了病毒粒子从感染细胞中的释放。
