Bartusch Christina, Prange Reinhild
Department of Medical Microbiology and Hygiene, University Medical Center of the Johannes Gutenberg University Mainz, Augustusplatz, Mainz D-55131, Germany.
Viruses. 2016 Apr 18;8(4):103. doi: 10.3390/v8040103.
The Murine Leukemia Virus (MLV) is a gammaretrovirus that hijack host components of the endosomal sorting complex required for transport (ESCRT) for budding. To determine the minimal requirements for ESCRT factors in MLV viral and viral-like particles (VLP) release, an siRNA knockdown screen of ESCRT(-associated) proteins was performed in MLV-producing human cells. We found that MLV VLPs and virions primarily engage the ESCRT-I factor Tsg101 and marginally the ESCRT-associated adaptors Nedd4-1 and Alix to enter the ESCRT pathway. Conversely, the inactivation of ESCRT-II had no impact on VLP and virion egress. By analyzing the effects of individual ESCRT-III knockdowns, VLP and virion release was profoundly inhibited in CHMP2A- and CHMP4B-knockdown cells. In contrast, neither the CHMP2B and CHMP4A isoforms nor CHMP3, CHMP5, and CHMP6 were found to be essential. In case of CHMP1, we unexpectedly observed that the CHMP1A isoform was specifically required for virus budding, but dispensable for VLP release. Hence, MLV utilizes only a subset of ESCRT factors, and viral and viral-like particles differ in ESCRT-III factor requirements.
小鼠白血病病毒（MLV）是一种γ逆转录病毒，它在出芽过程中劫持转运所需的内体分选复合物（ESCRT）的宿主成分。为了确定ESCRT因子在MLV病毒颗粒和病毒样颗粒（VLP）释放中的最低要求，我们在产生MLV的人类细胞中对ESCRT（相关）蛋白进行了小干扰RNA（siRNA）敲低筛选。我们发现，MLV病毒样颗粒和病毒体主要与ESCRT-I因子Tsg101相互作用，与ESCRT相关衔接蛋白Nedd4-1和Alix的相互作用较弱，从而进入ESCRT途径。相反，ESCRT-II的失活对病毒样颗粒和病毒体的释放没有影响。通过分析单个ESCRT-III敲低的影响，我们发现CHMP2A和CHMP4B敲低的细胞中，病毒样颗粒和病毒体的释放受到显著抑制。相比之下，未发现CHMP2B和CHMP4A异构体以及CHMP3、CHMP5和CHMP6是必需的。对于CHMP1，我们意外地观察到，CHMP1A异构体是病毒出芽所特需的，但对于病毒样颗粒的释放则不是必需的。因此，MLV仅利用一部分ESCRT因子，并且病毒颗粒和病毒样颗粒在ESCRT-III因子需求方面存在差异。
