广东某规模化猪场PCV2d感染的诊断与遗传进化分析

doi:10.16431/j.cnki.1671-7236.2025.06.030

摘要/Abstract

摘要： 【目的】确定广东某规模化猪场发病猪是否为猪圆环病毒2型(Porcine circovirus type 2，PCV2)感染，并评估病毒的遗传特性及其在猪群中的流行情况，为疫病的防控提供科学数据支持。【方法】采用实时荧光定量PCR和ELISA方法对猪场病猪的肾脏、淋巴结、脾脏等内脏组织及血清样本进行检测分析，并通过PCR扩增PCV2阳性样本的ORF2基因。利用DNAStar软件包中的MegAlign模块对所得ORF2基因序列与GenBank数据库中23株PCV2参考毒株进行相似性比对。运用Mega 7.0软件构建基于ORF2基因序列的遗传进化树，以明确鉴定毒株与参考毒株之间的遗传关系。【结果】流行病学调查、临床症状及病理解剖结果显示，该猪场病猪符合PCV2感染的特征。实时荧光定量PCR检测发现3份样本的Ct值分别为14.42、15.13和16.08，表明病毒载量较高，且PCV2检测结果为阳性。ELISA检测结果显示，不同日龄段猪群中Cap蛋白抗体阳性率介于60%～100%之间，而Rep蛋白抗体阳性率则在0～100%之间，特别是150日龄猪群的2种蛋白抗体阳性率均达到100%，表明PCV2感染强度较高。ORF2基因测序获得了3条序列，分别命名为LZC-2305-1、LZC-2305-2和LZC-2305-3。相似性分析结果显示，这3条序列间具有99.9%～100%的相似性，且与GenBank中的23株PCV2参考毒株序列的相似性为82.3%～99.7%，其中与CZ246序列相似性最高，为99.6%～99.7%。遗传进化树分析进一步证实，本研究获得的3条序列与CZ246序列具有最近的亲缘关系，归属于PCV2的2d分支。【结论】本研究确诊该猪场猪群发生了PCV2d分支的感染。本研究结果不仅为该猪场的PCV2防控提供了科学依据，也为其他规模化猪场的疫病监测与防控提供了参考。

关键词: 猪圆环病毒2型(PCV2); 诊断; 实时荧光定量PCR; ELISA; 遗传进化分析

Abstract: 【Objective】 This study was conducted to determine whether the morbid pigs in a pig farm in Guangdong were infected with Porcine circovirus type 2 (PCV2).It also evaluated the genetic characteristics of the virus and its prevalence in swine herds,so as to provide scientific data to support the prevention and control of epidemics.【Method】 Real-time quantitative PCR and ELISA were used to detect and analyze the visceral tissues such as kidneys,lymph nodes and spleens,as well as serum samples of sick pigs in the farm.This study further amplified and sequenced the ORF2 gene of PCV2-positive samples by PCR.Using the MegAlign module in the DNAStar software package,the resulting ORF2 gene sequences were comparatively analyzed for similarity with the 23 PCV2 reference strains in GenBank database.In addition,a genetic evolution tree based on the ORF2 gene sequences was constructed using Mega 7.0 software to clarify the genetic relationship between the identified and reference strains.【Result】 According to the epidemiological investigation,clinical symptoms and pathological autopsy results,the sick pigs in this farm were consistent with the characteristics of PCV2 infection.Real-time quantitative PCR test revealed that the Ct values of three samples were 14.42,15.13 and 16.08,respectively,indicating a high viral load and a positive PCV2 test result.ELISA results showed that the Cap protein antibody positivity rate ranged from 60% to 100% and that of Rep protein ranged from 0 to 100% in different age groups of pigs,especially in 150-day-old pigs,the antibody positivity rate of both proteins reached 100%,indicating a high intensity of PCV2 infection.Sequencing of the ORF2 gene yielded three sequences named LZC-2305-1,LZC-2305-2 and LZC-2305-3,respectively.Similarity analysis showed that these three sequences shared 99.9% to 100% similarity with each other and ranged from 82.3% to 99.7% similarity to the sequences of the 23 PCV2 reference strains in GenBank,with the highest similarity of 99.6% to 99.7% to CZ246 sequence.Genetic evolutionary tree analysis further confirmed that these sequences had the closest affinity to CZ246 sequences attributed to the 2d branch of PCV2.【Conclusion】 This study confirmed that the infection of PCV2d branch occurred in pigs of this farm.This study not only provided a scientific basis for the prevention and control of PCV2 in this farm,but also provided a reference for disease monitoring and control in other large-scale pig farms.

Key words: Porcine circovirus type 2 (PCV2); diagnosis; Real-time quantitative PCR; ELISA; genetic evolutionary analysis

中图分类号:

S852.65⁺1

钟玮霖, 尧建辉, 魏晓琪, 颜广智, 陈盛楠, 刘明杰, 黄良宗. 广东某规模化猪场PCV2d感染的诊断与遗传进化分析[J]. 中国畜牧兽医, 2025, 52(6): 2781-2789.

ZHONG Weilin, YAO Jianhui, WEI Xiaoqi, YAN Guangzhi, CHEN Shengnan, LIU Mingjie, HUANG Liangzong. Diagnosis and Genetic Evolution Analysis of PCV2d Infection in a Pig Farm in Guangdong[J]. China Animal Husbandry & Veterinary Medicine, 2025, 52(6): 2781-2789.

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