福建省新发猪圆环病毒3型流行病学调查及遗传变异分析

Epidemiological investigation and genetic diversity analysis of novel porcine circovirus type 3 in Fujian province

猪圆环病毒3型(PCV3)是新发现的一种猪圆环病毒,该病毒可以引起猪皮炎与肾病综合征(PDNS)、母猪繁殖障碍和全身多器官的炎症反应。为了解福建省PCV3流行株的现状、分子生物学特征和遗传演化规律,本研究采集福建地区规模化猪场120份临床表现繁殖障碍和呼吸道疾病的组织样品,采用PCR方法对其进行PCV3检测。结果显示福建省猪场PCV3的感染率为12.5%。对福建省5株PCV3全基因组进行序列分析,结果显示,5株PCV3间核苷酸同源性为98.2%~99.6%,与国内PCV3分离株的核苷酸同源性为97.6%~100%,与美国分离株(PCV3-US/MO2015、PCV3-US/MN2016、PCV3-US/SD2016、PCV3 2164和PCV3 29160)的核苷酸同源性为97.8%~99.3%,而与PCV2的核苷酸同源性为43.8%~44.1%,与我国蝙蝠圆环病毒的核苷酸同源性为49.2%~51.1%。PCV3系统进化树结果显示,福建省5株PCV3处于3大亚群,1株属于3a亚群,1株属于3b亚群,3株属于3c亚群。其氨基酸序列分析显示PCV3 Cap蛋白比较保守,仅存在个别位点的氨基酸突变。本研究为福建省PCV3的分子流行病学、疫苗研究和有效防控提供实验依据。

Porcine circovirus type 3 （PCV3） is a novel circovirus and is associated with porcine dermatitis and ncphropathy syndrome （PDNS）, failure and multi-organ inflammation. To understand the epidemic status, molecular epidemiology and phylogenetic relationship of PCV3, a total of 120 clinical samples （kidneys, livers, and lymph nodes） from pigs with reproductive failure and respiratory disease were collected from pigs farms in Fujian province from 2016 to 2017 and these samples were used to detect PCV3 by PCR. The results showed that PCV3 existed in swine herds and PCV3 positve rate was 12.5% in Fujian province. Sequencing of the complete genomes of 5 selected PCV3 strains showed they had nucleotide homologies of 98.2%-99.6% with each other, 97.6%-100% with domestic PCV3 isolates and 97.8%-99.3% with American PCV3 （PCV3-US/MO2015,PCV3-US/MN2016, PCV3-US/SD2016, PCV3 2164 and PCV3 29160）, but only 43.8%-44.1% with PCV2, 49.2%-51.1% with Chinese bat circovirus. The phylogenetic tree analysis showed that the PCV3 of Fujian was divided into three groups, PCV3a （1 isolate）, PCV3b （1 isolate） and PCV3c （3 isolates）. Meanwhile, the amino acid sequence analysis showed that PCV3 Cap protein was conserved and only few amino acid mutations were observed. Our data would help in understanding the evolutionary characteristics of PCV3, providing experimental basis for the vaccine development, prevention and control of PCV3 in Fujian province.