Table_3_Molecular Characterization of a Debilitation-Associated Partitivirus Infecting the Pathogenic Fungus Aspergillus flavus.DOCX

The opportunistic human pathogenic fungus Aspergillus flavus is known to be infected with mycoviruses. In this study, we report a novel mycovirus A. flavus partitivirus 1 (AfPV1) that was originally isolated from the abnormal colonial morphology isolate LD-3-8 of A. flavus. AfPV1 has spherical virus-like particles about 40 nm in diameter, and three double-stranded RNA (dsRNA) segments (dsRNA1, 2, and 3 with lengths of 1.7, 1.4, and 1.1 kbp, respectively) were packaged in the virions. dsRNA1, dsRNA2, and dsRNA3 each contained a single open reading frame and potentially encoded 62, 42, and 32 kDa proteins, respectively. The dsRNA1 encoded protein shows similarity to the RNA-dependent RNA polymerase (RdRp) of partitiviruses, and the dsRNA2 product has no significant similarity to any other capsid protein (CP) in the GenBank databases, beside some homology with the hypothetical “capsid” protein of a few partitiviruses. The dsRNA3 encodes a protein with no similarity to any protein in the GenBank database. SDS-PAGE and polypeptide mass fingerprint-mass spectrum (PMF-MS) analyses indicated that the CP of the AfPV1 was encoded by dsRNA2. Phylogenetic analysis showed that the AfPV1 and relative viruses were found in an unclassified group inside the Partitiviridae family. AfPV1 seems to result in debilitation symptoms, but had no significant effects to murine pathogenicity. These findings provide new insights into the partitiviruses taxonomy and the interactions between viruses and A. flavus.

机会性的人类致病真菌黄曲霉（Aspergillus flavus）已知感染有霉毒。在本研究中，我们报道了一种新型的霉毒黄曲霉分割病毒1（A. flavus partitivirus 1，简称AfPV1），该霉毒最初从黄曲霉异常菌落形态分离株LD-3-8中分离得到。AfPV1具有约40纳米直径的球形病毒样颗粒，并包含三个双链RNA（dsRNA）片段（dsRNA1、2、和3，分别长度为1.7、1.4和1.1千碱基对），这些片段被封装在病毒颗粒中。dsRNA1、dsRNA2和dsRNA3各自含有一个开放阅读框，并可能编码62、42和32千道尔顿的蛋白质。dsRNA1编码的蛋白与分割病毒的RNA依赖性RNA聚合酶（RdRp）相似，而dsRNA2产物与GenBank数据库中的任何其他衣壳蛋白（CP）无显著相似性，除了与少数分割病毒的假设“衣壳”蛋白存在一定同源性。dsRNA3编码的蛋白与GenBank数据库中的任何蛋白均无相似性。SDS-PAGE和肽链质量指纹-质谱（PMF-MS）分析表明，AfPV1的CP由dsRNA2编码。系统发育分析显示，AfPV1及其相关病毒被发现在分割病毒科中的一个未分类的组内。AfPV1似乎会导致衰弱症状，但对小鼠致病性没有显著影响。这些发现为分割病毒分类学和病毒与黄曲霉之间的相互作用提供了新的见解。