Molecular characterization of a Chinese vaccine strain of transmissible gastroenteritis virus: mutations that may contribute to attenuation.
Transmissible gastroenteritis virus (TGEV), the etiological agent of transmissible gastroenteritis (TGE), is the major cause of viral enteritis and fetal diarrhea in swine neonates, resulting in significant economic losses to the swine industry. The Chinese vaccine strain H165 of TGEV was derived from a virulent field strain H16 by serial passage in vitro. Strain H165 has been proven to be safe in piglets and pregnant sows and displays efficacy against TGEV infection. In this study, we report the complete genome sequences of strains H165 and H16, obtained by sequencing several overlapping fragments amplified from viral RNA and our findings from sequence and phylogenetic analyses. The genomes were 28,569 nucleotides in length, including the poly (A) tail. No deletions or insertions were detected in the H16 genome sequence after continuous passage in vitro; however, we found 27 nucleotide mutations in strain H165 compared with strain H16, resulting in 16 amino acid changes distributed among the genes 1, S, 3, and sM. An A to G nucleotide mutation was found in the intergenic region between the 3a and 3b genes. Furthermore, six unique nucleotides identified in the genome sequence of H165 could be used as makers to differentiate the H165 vaccine strain from wild-type TGEV strains. Our findings from phylogenetic analysis may enhance our understanding of the evolution of TGEV, as well as the other coronaviruses.
Division of Swine Infectious Diseases, National Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of the Chinese Academy of Agricultural Sciences, Nangang District, Harbin 150001, People's Republic of China.
Chengbao
C
Wang
Jianfei
J
Chen
Hongyan
H
Shi
Huaji
H
Qiu
Fei
F
Xue
Changming
C
Liu
Yuanmao
Y
Zhu
Shengwang
S
Liu
Fernando
F
Almazán
Luis
L
Enjuanes
Li
L
Feng
D019943:Amino Acid Substitution / Q000235:genetics; D000818:Animals; D002681:China; D016000:Cluster Analysis; D005761:Gastroenteritis, Transmissible, of Swine / Q000517:prevention & control*; D016679:Genome, Viral; D008969:Molecular Sequence Data; D010802:Phylogeny; D017354:Point Mutation; D012333:RNA, Messenger; D012367:RNA, Viral / Q000235:genetics*; D017422:Sequence Analysis, DNA; D017385:Sequence Homology; D012692:Serial Passage; D013552:Swine; D005760:Transmissible gastroenteritis virus / Q000235:genetics*; D014613:Vaccines, Attenuated / Q000235:genetics; D014765:Viral Vaccines / Q000235:genetics*
D012333:RNA, Messenger; D012367:RNA, Viral; D014613:Vaccines, Attenuated; D014765:Viral Vaccines