Characterization of a human foamy virus 170-kilodalton Env-Bet fusion protein generated by alternative splicing
Characterization of a human foamy virus 170-kilodalton Env-Bet fusion protein generated by alternative splicing
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DOI：
10.1128/jvi.72.5.4088-4094.1998
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发表时间：
1998-05-01
影响因子：
5.4
通讯作者：
Rethwilm, A
中科院分区：
文献类型：
--
作者：
Lindemann, D;Rethwilm, A
灵长类泡沫病毒（FVs）除了表达130 kda的包膜蛋白外，还表达170 kda的糖蛋白，该糖蛋白可与包膜蛋白和Bel蛋白特异性抗血清反应。我们利用分子克隆的人流感病毒（HFV）确定了这个170 kda糖蛋白的确切性质。使用HFV Env、Bel1和Bel2蛋白特异性抗血清对转染适当表达构建的293T细胞进行放射免疫沉淀分析，以及HFV感染细胞的逆转录- pcr分析表明，该蛋白是一种Env- bet融合蛋白，分泌到上清液中，然而，它仅与病毒颗粒松散相关，或不相关。gp170是由位于环境开放阅读框（ORF）内的剪接供体和剪接受体对交替剪接的Env mRNA产生的，通常用于产生来自环境开放阅读框内部启动子的Bel1和Bet转录本，gp170的表达水平为环境前体gp130的30 - 50%。然而，仅表达gp170的原病毒衍生的衣壳不会被释放到上清液中，因此，仅表达gp170的原病毒克隆衍生的病毒在体外感染性和复制动力学上与野生型病毒相似。此外，两种病毒通过中和血清灭活的程度相似，这表明gp170的脱落可能不会影响受感染宿主的体液免疫反应。
Primate foamy viruses (FVs) express, in addition to the 130-kDa envelope protein, a 170-kDa glycoprotein, which reacts with antisera specific for the envelope and Bel proteins. We determined the exact nature of this 170-kDa glycoprotein by using the molecularly cloned human FV (HFV). Radioimmunoprecipitation analysis of 293T cells transfected with appropriate expression constructs by using antisera specific for the HFV Env, Bel1, and Bel2 proteins, as well as reverse transcription-PCR analysis of HFV-infected cells, demonstrated that this protein is an Env-Bet fusion protein that is secreted into the supernatant, However, it is only loosely associated, or not associated, with viral particles, gp170 is generated by an alternatively spliced Env mRNA using a splice donor and splice acceptor pair localized within the env open reading frame (ORF), which is normally used to generate Bel1 and Bet transcripts derived from the internal promoter within the env ORF, gp170 is expressed at a level 30 to 50% of the Env precursor gp130. However, it alone does not confer infectivity to HFV particles, because capsids derived from proviruses expressing only the gp170 were not released into the supernatant, In contrast, viruses derived from proviral clones deficient in gp170 expression showed similar in vitro infectivity and replication kinetics to wild-type virus. Furthermore, both types of viruses were inactivated to a similar extent by neutralizing sera, indicating that shedding of gp170 probably does not affect the humoral immune response in the infected host.