Comparative genomic analysis of five pairs of virulent parental/attenuated vaccine strains of PRRSV.
Porcine reproductive and respiratory syndrome virus (PRRSV), the causative agent of porcine reproductive and respiratory syndrome, is responsible for serious disease in pigs resulting in substantial economic losses in the porcine industry. An attenuated vaccine strain, HuN4-F112, was obtained by passaging virulent PRRSV strain HuN4 on Marc-145 cells (for 112 passages), and the full-genomic sequence was determined. To understand the molecular basis of attenuation of PRRSV, we compared and analyzed the genomic sequences of HuN4/HuN4-F112, together with those of other four virulent parental/attenuated vaccine strains. Among the 19 PRRSV proteins, two (NSP6 and NSP8) were highly conserved, without any mutations and considered irrelative to attenuation. The mutation rates of envelope-associated structural proteins were obviously higher than those of most non-structural proteins. It is interesting that the gene of the smallest structural protein, E protein, had the highest mutation rate among all of the structural genes analyzed, and also harbored a highly variable region. Our results indicate that determinants of PRRSV attenuation are multigenic products of both non-structural and structural genes. To our knowledge, this is the first report showing that the envelope-associated structural proteins (including E and GP2-GP5 proteins) may play a significant role. These findings contribute towards our understanding of PRRSV attenuation and will provide an important clue for further study.
Division of Swine Infectious Diseases, National Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin 150001, China.
Tong-Qing
TQ
An
Zhi-Jun
ZJ
Tian
Yan-Jun
YJ
Zhou
Yan
Y
Xiao
Jin-Mei
JM
Peng
Jin
J
Chen
Yi-Feng
YF
Jiang
Xiao-Fang
XF
Hao
Guang-Zhi
GZ
Tong
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D055028:Comparative Genomic Hybridization; D016679:Genome, Viral; D006023:Glycoproteins / Q000235:genetics; D009154:Mutation; D019316:Porcine respiratory and reproductive syndrome virus / Q000235:genetics*; D012367:RNA, Viral; D016415:Sequence Alignment; D017423:Sequence Analysis, RNA; D012689:Sequence Homology, Nucleic Acid; D013552:Swine / Q000821:virology; D014613:Vaccines, Attenuated; D017361:Viral Nonstructural Proteins / Q000235:genetics*; D015678:Viral Structural Proteins / Q000235:genetics*
D006023:Glycoproteins; D012367:RNA, Viral; D014613:Vaccines, Attenuated; D017361:Viral Nonstructural Proteins; D015678:Viral Structural Proteins