title: In vitro adaptation and genome analysis of a sub-subgenotype 2.1c isolate of classical swine fever virus.
abstract: Classical swine fever (CSF) still causes substantial economic losses in the pig industry in China. This study reports the isolation and characterization of a field CSF virus named GD53/2011 from pig kidney tissue collected during a CSF outbreak in Guangdong province, China. Phylogenetic analysis based on the full-length E2 gene sequence revealed that this isolate belongs to CSFV sub-subgenotype 2.1c. To further understand the replication characteristics, GD53/2011 was subsequently adapted in PK-15 cells, and its full-length genome was sequenced. After adaptation in PK-15 cells, the titer of GD53/2011 was significantly increased from 10(3.39) TCID50/ml at passage 6 (F6) to 10(8.50) TCID50/ml at passage 46 (F46) with the peak titer obtained at 48 h post-inoculation. Sequence comparison revealed that the E(rns) gene at passages 6, 15, and 25 of GD53/2011 was identical to that in the original tissue, but one amino acid substitution (S476R) was detected at passages 35 and 46. Furthermore, E2 gene sequences at passages 6, 15, 25, 35, and 46 was found identical to that in the original tissue, indicating that the E2 gene was stable during CSF virus adaptation in PK-15 cells. Full-length protein sequence comparison of GD53/2011 with other 2.1 sub-subgenotype isolates showed that Core and NS5A, rather than E2, are more genetically variable. Taken together, a field CSFV strain GD53/2011 was isolated, fully sequenced, and adapted to high growth titer in PK-15 cells, which might be suitable for future studies on CSFV infection, replication, and vaccine development.
authors.affiliation: Institute of Military Veterinary, Academy of Military Medical Sciences, Changchun, 130122, China.|Department of Anatomy and Physiology, College of Veterinary Medicine, Kansas State University, Manhattan, 66506, USA.
authors.forename: Wenjie
authors.initials: W
authors.lastname: Gong
authors.affiliation: College of Life Science, Foshan University, Foshan, Guangdong, 528231, China.
authors.forename: Zongji
authors.initials: Z
authors.lastname: Lu
authors.affiliation: Institute of Military Veterinary, Academy of Military Medical Sciences, Changchun, 130122, China.|College of Animal Science and Technology, Jilin Agricultural University, Changchun, 130122, China.
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.affiliation: Institute of Military Veterinary, Academy of Military Medical Sciences, Changchun, 130122, China.|College of Animal Science and Technology, Jilin Agricultural University, Changchun, 130122, China.
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Xie
authors.affiliation: Institute of Military Veterinary, Academy of Military Medical Sciences, Changchun, 130122, China.
authors.forename: Daliang
authors.initials: D
authors.lastname: Jiang
authors.affiliation: Institute of Military Veterinary, Academy of Military Medical Sciences, Changchun, 130122, China.
authors.forename: Junjie
authors.initials: J
authors.lastname: Jia
authors.affiliation: Institute of Military Veterinary, Academy of Military Medical Sciences, Changchun, 130122, China.
authors.forename: Huancheng
authors.initials: H
authors.lastname: Guo
authors.affiliation: Department of Anatomy and Physiology, College of Veterinary Medicine, Kansas State University, Manhattan, 66506, USA. jshi@ksu.edu.
authors.forename: Jishu
authors.initials: J
authors.lastname: Shi
authors.affiliation: Institute of Military Veterinary, Academy of Military Medical Sciences, Changchun, 130122, China. changchun_tu@hotmail.com.|Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China. changchun_tu@hotmail.com.
authors.forename: Changchun
authors.initials: C
authors.lastname: Tu
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution / Q000235:genetics; D000818:Animals; D002681:China; D006691:Classical Swine Fever / Q000821:virology*; D006692:Classical Swine Fever Virus / Q000235:genetics*; D016679:Genome, Viral / Q000235:genetics*; D005838:Genotype; D010802:Phylogeny; D016415:Sequence Alignment / Q000379:methods; D013552:Swine; D014759:Viral Envelope Proteins / Q000235:genetics
chemical_list: D014759:Viral Envelope Proteins
keywords: CSFV; Cellular adaptation; Field virus; Sub-subgenotype 2.1c