Emergence of fatal PRRSV variants: unparalleled outbreaks of atypical PRRS in China and molecular dissection of the unique hallmark.
Porcine reproductive and respiratory syndrome (PRRS) is a severe viral disease in pigs, causing great economic losses worldwide each year. The causative agent of the disease, PRRS virus (PRRSV), is a member of the family Arteriviridae. Here we report our investigation of the unparalleled large-scale outbreaks of an originally unknown, but so-called "high fever" disease in China in 2006 with the essence of PRRS, which spread to more than 10 provinces (autonomous cities or regions) and affected over 2,000,000 pigs with about 400,000 fatal cases. Different from the typical PRRS, numerous adult sows were also infected by the "high fever" disease. This atypical PRRS pandemic was initially identified as a hog cholera-like disease manifesting neurological symptoms (e.g., shivering), high fever (40-42 degrees C), erythematous blanching rash, etc. Autopsies combined with immunological analyses clearly showed that multiple organs were infected by highly pathogenic PRRSVs with severe pathological changes observed. Whole-genome analysis of the isolated viruses revealed that these PRRSV isolates are grouped into Type II and are highly homologous to HB-1, a Chinese strain of PRRSV (96.5% nucleotide identity). More importantly, we observed a unique molecular hallmark in these viral isolates, namely a discontinuous deletion of 30 amino acids in nonstructural protein 2 (NSP2). Taken together, this is the first comprehensive report documenting the 2006 epidemic of atypical PRRS outbreak in China and identifying the 30 amino-acid deletion in NSP2, a novel determining factor for virulence which may be implicated in the high pathogenicity of PRRSV, and will stimulate further study by using the infectious cDNA clone technique.
Tian
Kegong
K
China Animal Disease Control Center, Beijing, China. tiankg@263.net
Yu
Xiuling
X
Zhao
Tiezhu
T
Feng
Youjun
Y
Cao
Zhen
Z
Wang
Chuanbin
C
Hu
Yan
Y
Chen
Xizhao
X
Hu
Dongmei
D
Tian
Xinsheng
X
Liu
Di
D
Zhang
Shuo
S
Deng
Xiaoyu
X
Ding
Yinqiao
Y
Yang
Lu
L
Zhang
Yunxia
Y
Xiao
Haixia
H
Qiao
Mingming
M
Wang
Bin
B
Hou
Lili
L
Wang
Xiaoying
X
Yang
Xinyan
X
Kang
Liping
L
Sun
Ming
M
Jin
Ping
P
Wang
Shujuan
S
Kitamura
Yoshihiro
Y
Yan
Jinghua
J
Gao
George F
GF
D000595:Amino Acid Sequence; D000818:Animals; D000831:Animals, Newborn / Q000235:genetics / Q000821:virology; D002681:China / Q000453:epidemiology; D004196:Disease Outbreaks; D005814:Genes, Viral; D014644:Genetic Variation; D016679:Genome, Viral; D007124:Immunoenzyme Techniques; D008969:Molecular Sequence Data; D019318:Porcine Reproductive and Respiratory Syndrome / Q000453:epidemiology* / Q000235:genetics; D019316:Porcine respiratory and reproductive syndrome virus / Q000235:genetics* / Q000472:pathogenicity*; D017386:Sequence Homology, Amino Acid; D013552:Swine / Q000235:genetics / Q000821:virology