Mahbub Alam M, Kobayashi N, Ishino M, Naik T N, Taniguchi K
Department of Veterinary Medicine, Faculty of Veterinary Science, Bangladesh Agricultural University, Mymensingh, Bangladesh.
Arch Virol. 2006 Nov;151(11):2149-59. doi: 10.1007/s00705-006-0795-y. Epub 2006 Jun 16.
Reassortment is one of the major evolutionary mechanisms of the rotavirus genome. Preferential selection (assortment) of the NSP1 gene segment from either of the parental viruses after coinfection of these viruses has been reported as a notable finding in reassortment. To analyze genetic factors which are associated with preferential selection of the rotavirus NSP1 gene segment into progeny viruses, mixed infection and multiple passages were performed using two panels of rotaviruses, i.e., bovine rotavirus A5 clones, and simian rotavirus SA11 and five strains of SA11-based single NSP1 gene-substitution reassortants. In the first experiment, three A5 clones (A5-10, A5-13, and A5-16) that had genetically distinct NSP1 genes in the same genetic background were used. In coinfection of these A5 clones, it was noted that the A5-10 NSP1 gene, which encodes an incomplete protein product due to presence of a nonsense codon at an unusual position, was selected more preferentially than the A5-13 NSP1 gene with intact length and structure. The A5-16 NSP1 gene, with a deletion of 500 bp, was least efficiently selected. In the second experiment, we prepared two reassortants, SOF and SRF, which have NSP1 genes from rotavirus strains OSU and RRV, respectively, in the genetic background of SA11, which were used together with previously prepared reassortants SKF, SDF, and SNF, which had NSP1 genes from strains KU, DS1, and K9, respectively. Among the 6 NSP1 genes analyzed, the NSP1 gene from SKF was most preferentially selected, followed by SNF, SOF, SDF, SA11, and SRF, in that order. Although SOF exhibited less growth efficacy than SA11, the growth rates of other reassortants were similar to that of SA11. These findings suggest that for the occurrence of preferential selection of the NSP1 gene, production of the intact NSP1 protein may not be involved, but the presence of intact length of the NSP1 gene may be required. Furthermore, it was also found that genetic similarity based on primary structure of this gene is not related to the selectivity of the NSP1 gene.
基因重配是轮状病毒基因组主要的进化机制之一。据报道，在这些病毒共同感染后，从亲代病毒中优先选择（重配）NSP1基因片段是基因重配中的一个显著发现。为了分析与轮状病毒NSP1基因片段优先选择进入子代病毒相关的遗传因素，使用两组轮状病毒进行了混合感染和多次传代实验，即牛轮状病毒A5克隆株，以及猴轮状病毒SA11和五株基于SA11的单NSP1基因替换重配株。在第一个实验中，使用了在相同遗传背景下具有基因不同的NSP1基因的三个A5克隆株（A5 - 10、A5 - 13和A5 - 16）。在这些A5克隆株的共同感染中，注意到A5 - 10的NSP1基因，由于在一个不寻常位置存在无义密码子而编码一种不完整的蛋白质产物，比具有完整长度和结构的A5 - 13 NSP1基因更优先被选择。缺失500 bp的A5 - 16 NSP1基因被选择的效率最低。在第二个实验中，我们制备了两个重配株，SOF和SRF，它们在SA11的遗传背景中分别具有来自轮状病毒株OSU和RRV的NSP1基因，将它们与先前制备的分别具有来自KU、DS1和K9株的NSP1基因的重配株SKF、SDF和SNF一起使用。在分析的6个NSP1基因中，来自SKF的NSP1基因被最优先选择，其次是SNF、SOF、SDF、SA11和SRF，顺序依次如此。尽管SOF的生长效率低于SA11，但其他重配株的生长速率与SA11相似。这些发现表明，对于NSP1基因优先选择的发生，可能不涉及完整NSP1蛋白的产生，但可能需要NSP1基因具有完整长度。此外，还发现基于该基因一级结构的遗传相似性与NSP1基因的选择性无关。
