Marucci Gianluca, Zullino Ilaria, Bertuccini Lucia, Camerini Serena, Cecchetti Serena, Pietrantoni Agostina, Casella Marialuisa, Vatta Paolo, Greenwood Alex D, Fiorillo Annarita, Lalle Marco
Unit of Foodborne and Neglected Parasitic Disease, Department of Infectious Diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
Core Facilities, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
Biomedicines. 2021 Jun 8;9(6):654. doi: 10.3390/biomedicines9060654.
Giardiasis, caused by the protozoan parasite , is an intestinal diarrheal disease affecting almost one billion people worldwide. A small endosymbiotic dsRNA viruses, virus (GLV), genus , family , might inhabit human and animal isolates of . Three GLV genomes have been sequenced so far, and only one was intensively studied; moreover, a positive correlation between GLV and parasite virulence is yet to be proved. To understand the biological significance of GLV infection in , the characterization of several GLV strains from naturally infected isolates is necessary. Here we report high-throughput sequencing of four GLVs strains, from isolates of human and animal origin. We also report on a new, unclassified viral sequence (designed GdRV-2), unrelated to , encoding and expressing for a single large protein with an RdRp domain homologous to and . The result of our sequencing and proteomic analyses challenge the current knowledge on GLV and strongly suggest that viral capsid protein translation unusually starts with a proline and that translation of the RNA-dependent RNA polymerase (RdRp) occurs via a +1/-2 ribosomal frameshift mechanism. Nucleotide polymorphism, confirmed by mass-spectrometry analysis, was also observed among and between GLV strains. Phylogenetic analysis indicated the occurrence of at least two GLV subtypes which display different phenotypes and transmissibility in experimental infections of a GLV naïve isolate.
贾第虫病由原生动物寄生虫引起，是一种肠道腹泻疾病，全球近10亿人受其影响。一种小型内共生双链RNA病毒，即贾第虫病毒（GLV），属于小双节段RNA病毒属，双顺反子病毒科，可能存在于贾第虫的人类和动物分离株中。到目前为止，已对三个GLV基因组进行了测序，且仅对其中一个进行了深入研究；此外，GLV与寄生虫毒力之间的正相关关系尚待证实。为了解GLV感染在贾第虫中的生物学意义，有必要对来自自然感染的贾第虫分离株的几种GLV毒株进行特性分析。在此，我们报告了来自人类和动物源贾第虫分离株的四种GLV毒株的高通量测序结果。我们还报告了一种新的、未分类的病毒序列（命名为GdRV - 2），它与贾第虫病毒无关，编码并表达一种单一的大蛋白，该蛋白具有一个与丙型肝炎病毒和丁型肝炎病毒同源的RNA依赖RNA聚合酶（RdRp）结构域。我们的测序和蛋白质组学分析结果对目前关于GLV的认识提出了挑战，并强烈表明病毒衣壳蛋白的翻译异常地从脯氨酸开始，且RNA依赖RNA聚合酶（RdRp）的翻译通过 +1/-2核糖体移码机制发生。通过质谱分析证实，在GLV毒株之间以及毒株内部也观察到了核苷酸多态性。系统发育分析表明至少存在两种GLV亚型，它们在未感染GLV的贾第虫分离株的实验感染中表现出不同的表型和传播性。
