Infectious diseases have become the major problem with the development of large-scale pig industry in China.Multiple infections often occur on many pig farms.In the present study,185 samples collected from pigs of eight provinces in 2010 were tested in PCR or RT-PCR for porcine reproductive and respiratory syndrome virus（PRRSV）,classical swine fever virus（CSFV）,porcine circovirus type 2（PCV2）,porcine parvovirus（PPV）,pseudorabies virus（PRV） and Torque teno virus 2（TTV2）.The results showed that positive rates for PCV2,PRRSV and TTV2 were 49.2%,62.2% and 95.1%,respectively.In some swine herds,positive rate of TTV2 infection was 100%.In addition,mixed infections were found common with 27.6% for PRRSV/PCV2,45.4% for PRRSV/TTV2,58.4% for PCV2/TTV2 and even 24.9% for PCV2/TTV2/PRRSV.Furthermore,sequence analysis of GP5 and nsp2 genes from some of PRRSV positive samples revealed 98.2% or 96.2% identities with those of the highly pathogenic PRRSV（HP-PRRSV） HuN4 strain and a discontinued deletion of 30 amino acids in nsp2 region,indicating widespread of HP-PRRSV in pig herds.The information obtained from these investigations can be used to outline prevention and control of viral diseases.%随着规模化养猪业的发展,传染性疾病越来越多,混合感染或多重感染十分普遍,给疾病的诊断和预防带来很大困难。本文将我们实验室2010年分别采自福建、广西、河南、上海、内蒙、浙江、江苏和山西等地发病猪场的185份病料,通过RT-PCR和PCR方法对其进行猪繁殖与呼吸综合征病毒（Porcine reproductive and respiratory syndrome virus,PRRSV）、猪繁殖障碍的猪瘟病毒（Classical swine fever virus,CSFV）、猪圆环病毒2（Porcine circovirus type 2,PCV2）、猪细小病毒（Porcine parvovirus,PPV）、猪伪狂犬病毒（Pseudorabies virus,PRV）、细环病毒2（Torque teno virus 2,TTV2）等病毒检测。结果表明在所检的病料中PRRSV、PCV2和TTV2的阳性率比较高,分别为49.2%、62.2%和95.1%。有些地方TTV2的阳性率高达100%;同时,还存在很普遍的PRRSV与PCV2、PRRSV与TTV2、PCV2与TTV2等混合感染,混合感染率分别为27.6%、45.4%、58.4%;以及PRRSV、PCV2与TTV2的三重感染率为24.9%。同时对部分PRRSV阳性病料的PRRSV GP5和nsp2基因分别进行测序,分析测序结果表明病料中的PRRSV的GP5和nsp2序列与PRRSV HuN4株的相应序列的亲缘关系分别在98.2%和96.2%以上,且在nsp2区域都存在30个不连续氨基酸的缺失,说明现在临床中所流行的PRRSV可能仍是与高致病性PRRSV基因型相似的病毒。通过本文可以及时了解当前养猪场的病毒性疾病的流行情况,为猪场病毒性疾病的防控提供依据。
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