泰国猪繁殖与呼吸综合征病毒（PRRSV）的遗传学与地理变异
Genetics and geographical variation of porcine reproductive and respiratory syndrome virus (PRRSV) in Thailand.
作者信息
Thanawongnuwech R, Amonsin A, Tatsanakit A, Damrongwatanapokin S
机构信息
Department of Veterinary Pathology, Faculty of Veterinary Science, Chulalongkorn University, Henri Dunant Road, Pathumwan, Bangkok 10330, Thailand.
出版信息
Vet Microbiol. 2004 Jun 10;101(1):9-21. doi: 10.1016/j.vetmic.2004.03.005.
The Thai isolates of porcine reproductive and respiratory syndrome virus (PRRSV) were obtained from the Chulalongkorn University-Veterinary Diagnostic Laboratory (CU-VDL). Virus isolation was confirmed by immunoperoxidase monolayer assay (IPMA) using SDOW-17. The virus genotype was determined using nested multiplex RT-PCR (nm RT-PCR) of ORF 1b. The nm RT-PCR was able to detect at least 10TCID50/ml of PRRSV. Of 137 Thai isolates, 66.42% belonged to the European (EU) genotype and 33.58% to the North American (US) genotype. ORF5 products of the eight US strains (00CS1, 01NP1, 01UD6, 02CB13, 02KK1, 02PB1, 02SP2 and 02SP3) and the six EU strains (01CB1, 01RB1, 02BR1, 02CB12, 02SB2 and 03RB1) were sequenced for genetic variation analysis. The US strains of the Thai isolates are clustered within the same group and are more closely related to the IAF-EXP91 from Canada (89-90% nucleotide identity), whereas the EU strains were very similar to the EU prototype, Lelystad virus (87-97.5% nucleotide identity). The ORF5 nucleotide identities within the US genotype tested in this study compared to the US prototype, VR-2332 varied from 83.7 to 85.2%, whereas 83.5-85.5% amino acid identities were found. Based on the phylogenetic tree, each pair of the Thai isolates (01NP1 and 02KK1, 00CS1 and 01UD6, and 01CB1 and 01RB1) was identical despite they were collected from different provinces. Therefore, there was no geographic influence on the spreading of PRRSV in Thailand. Interestingly, 02CB12 (EU genotype) shared over 99% similarity of the ORF5 nucleotide sequence and 98.6% of amino acid identity with the European vaccine, Porcillis (AF378819). However, modified live virus vaccines for PRRSV have not yet been used in the swine population in Thailand. The results suggested that both US and EU genotypes exist in Thailand, genetic variation does occur in both genotypes, and the sources of the viruses appear to be from Canada and Northern Europe, respectively. In addition, the spreading of PRRSV in Thailand might be due to introducing infected replacement pigs or infected semen into the farm.
泰国猪繁殖与呼吸综合征病毒（PRRSV）分离株取自朱拉隆功大学兽医诊断实验室（CU - VDL）。通过使用SDOW - 17的免疫过氧化物酶单层试验（IPMA）确认病毒分离。使用ORF 1b的巢式多重RT - PCR（nm RT - PCR）确定病毒基因型。nm RT - PCR能够检测到至少10TCID50/ml的PRRSV。在137株泰国分离株中，66.42%属于欧洲（EU）基因型，33.58%属于北美（US）基因型。对8株美国毒株（00CS1、01NP1、01UD6、02CB13、02KK1、02PB1、02SP2和02SP3）和6株欧洲毒株（01CB1、01RB1、02BR1、02CB12、02SB2和03RB1）的ORF5产物进行测序以进行遗传变异分析。泰国分离株中的美国毒株聚集在同一组内，并且与来自加拿大的IAF - EXP91关系更密切（核苷酸同一性为89 - 90%），而欧洲毒株与欧洲原型莱利斯塔德病毒非常相似（核苷酸同一性为87 - 97.5%）。本研究中测试的美国基因型内的ORF5核苷酸同一性与美国原型VR - 2332相比，在83.7%至85.2%之间，而氨基酸同一性为83.5 - 85.5%。基于系统发育树，尽管泰国分离株（01NP1和02KK1、00CS1和01UD6以及01CB1和01RB1）分别来自不同省份，但每对分离株的序列相同。因此，PRRSV在泰国的传播没有受到地理因素的影响。有趣的是，02CB12（欧洲基因型）与欧洲疫苗Porcillis（AF378819）的ORF5核苷酸序列相似度超过99%，氨基酸同一性为98.6%。然而，PRRSV的改良活病毒疫苗尚未在泰国猪群中使用。结果表明，美国和欧洲基因型在泰国均存在，两种基因型均发生了遗传变异，并且病毒来源似乎分别来自加拿大和北欧。此外，PRRSV在泰国的传播可能是由于将感染的后备猪或感染的精液引入农场所致。
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