Morozov I, Meng X J, Paul P S
Veterinary Medical Research Institute, College of Veterinary Medicine, Iowa State University, Ames, USA.
Arch Virol. 1995;140(7):1313-9. doi: 10.1007/BF01322758.
The sequence of ORFs 2 to 4 of a U.S. isolate of porcine reproductive and respiratory syndrome virus (PRRSV), ATCC VR2385, was determined by analysis of a cDNA lambda library. The cDNA clones containing PRRSV specific sequences were selected using a VR2385 ORF 4 specific PCR probe and sequenced. The ORFs 2, 3 and 4 overlapped each other and encoded polypeptides with predicted M(r) of 29.5 kDa (ORF 2), 28.7 kDa (ORF 3) and 19.5 kDa (ORF 4), respectively. No overlap was found between ORFs 4 and 5, and instead there was a 10 bp sequence which separated these two ORFs. The nucleic acid homology with corresponding ORFs of the European PRRSV isolate Lelystad virus (LV) was 65% for ORF 2, 64% for ORF 3 and 66% for ORF 4. Comparison of the ORF 4 sequences of VR2385 with that of another U.S. isolate MN-1b revealed only 86% amino acid sequence homology and the presence of deletions in the ORF 4 of MN-1b. Our results further strengthen the observation that there is sequence variation between US and European PRRSV isolates.
通过对一个cDNA λ文库进行分析，确定了美国猪繁殖与呼吸综合征病毒（PRRSV）毒株ATCC VR2385的开放阅读框（ORF）2至4的序列。使用VR2385 ORF 4特异性PCR探针筛选出含有PRRSV特异性序列的cDNA克隆并进行测序。ORF 2、3和4相互重叠，分别编码预测分子量为29.5 kDa（ORF 2）、28.7 kDa（ORF 3）和19.5 kDa（ORF 4）的多肽。在ORF 4和5之间未发现重叠，相反，有一个10 bp的序列将这两个ORF分隔开。与欧洲PRRSV毒株莱利斯塔德病毒（LV）的相应ORF相比，ORF 2的核酸同源性为65%，ORF 3为64%，ORF 4为66%。将VR2385的ORF 4序列与另一个美国毒株MN-1b的序列进行比较，发现氨基酸序列同源性仅为86%，且MN-1b的ORF 4存在缺失。我们的结果进一步证实了美国和欧洲PRRSV毒株之间存在序列变异这一观察结果。
