新型猪星状病毒鉴定与致病性研究

Diarrhea caused by virus is a serious disease that affect the outcome of the pig industry.Astrovirus(AstV) has been determined to be the second most common cause of gastroenteritis after rotavirus. Furthermore, it was reported that AstV can cause serious extraintestinal manifestations in mammalian and avian hosts,such as fatal hepatitis in ducks, interstitial nephritis and growth retardation in young chickens, and stunting and prehatching mortality in duck and goose embryos.Moreover, recently an AstV was demonstrated to be the causative agent of encephalitis in a 15-year-old boy with agammaglobulinaemia, and shaking mink syndrome has also been associated with an AstV. Traditional porcine astrovirus (PAstV1) has been determined to cause mild diarrhea in colostrum-deprived, 4-day-old pigs. However,several new PAstV(PAstV2-5)has been discovered in diseased and healthy pigs in some very recent reports, and among them, PAstV2 and PAstV4 were revealed to have the highest prevalence, showing possible association with diarrhea of swine, while PAstV3 has the highest homology with the AstV from human and other hosts which can cause extraintestinal disease. Hitherto, the pathogenicity of these new PAstV types in pig is still unknown. In China, there are few study on PAstV, especially about the novel PAstVs. In this project, based on the previous studies of the applicant, a systematic investigation of the PAstVs will be carried out from different locations of China to define the distribution and prevalence of PAstVs in China, and the predominant type of PAstV in circulation. Moreover, the association of PAstV with swine enteric or extraintestinal disease will also be analyized. The results will provide basic data for the further study of the pathogenicity and pathogenic mechanism of PAstVs.

幼龄猪病毒性腹泻是严重影响养猪业的重要疾病。星状病毒（AstV）是仅次于轮状病毒引起小孩胃肠炎的重要病毒。除引起肠道疾病外，最近发现AstV亦能导致严重的非肠道疾病，如可引起免疫缺陷小孩脑炎、水貂系统性震颤。传统猪星状病毒（PAstV1）可引起幼龄猪轻度腹泻。近年来在腹泻和健康猪中发现了多种新型猪星状病毒（PAstV2-5），其中PAstV2、PAstV4流行率最高且可能与腹泻相关，而PAstV3则与引起人和其它动物肠道外疾病AstV同源性最高。但目前关于这些新型PAstV确切致病性尚无报道。当前对我国PAstV的研究很少。本项目拟建立PAstV1-5型的定量PCR检测方法，检测PAstV各型在我国分布与流行情况，确定PAstV在我国的主要流行类型，并通过分子流行病学数据初步分析其与猪腹泻及腹泻外症状的相关性，为进一步研究PAstV各型的致病性及致病机制提供基础数据。

本课题由于变更为1年期的小额项目，原申报研究内容已修改。目前，在本项目的资助下，已建立了检测猪星状病毒（PAstV）各型的多重定量PCR方法，调查了来自湖南、浙江和重庆三个省市共28个猪场的264份粪便、肛拭子和肠道组织样品，已在这些样品检测出PAstV1、PAstV2、PAstV4 和PAstV5，其中PAstV4的检出率最高(34.1%)，其次为PAstV1型和2型，阳性率均为3.4%。同时测定了各型部分代表株的序列。这些结果表明我国除传统的PAstV1, 新型星状病毒PAstV2,4和5型在我国均有分布。结果为进一步研究新型星状病毒的致病性和致病机制提供基本数据。