title: Competitive replication kinetics and pathogenicity in pigs co-infected with historical and newly invading classical swine fever viruses.
abstract: Classical swine fever (CSF), an economically important and highly contagious disease of pigs, is caused by classical swine fever virus (CSFV). In Taiwan, CSFVs from field outbreaks belong to two distinct genotypes. The historical genotype 3.4 dominated from the 1920s to 1996, and since 1996, the newly invading genotype 2.1 has dominated. To explain the phenomenon of this virus shift in the field, representative viruses belonging to genotypes 2.1 and 3.4 were either inoculated alone (single infection) or co-inoculated (co-infection), both in vivo and in vitro, to compare the virus replication and pathogenesis. In pigs co-infected with the genotype 2.1 TD/96/TWN strain and the genotype 3.4 94.4/IL/94/TWN strain, the newly invading genotype 2.1 was detected earlier in the blood, oral fluid, and feces, and the viral loads were consistently and significantly higher than that of the historical genotype 3.4. In cell cultures, the ratio of secreted virus to cell-associated virus of the genotype 2.1 strain was higher than that of the genotype 3.4 strain. This study is the first to demonstrate a possible explanation of virus shift in the field, wherein the newly invading genotype 2.1 replicates more efficiently than did genotype 3.4 and outcompetes the replication and pathogenicity of genotype 3.4 in pigs in the field.
authors.affiliation: Animal Health Research Institute, Council of Agriculture, Executive Yuan, 376 Chung-Cheng Road, Tansui, New Taipei City, 25158, Taiwan. Electronic address: ylhuang@mail.nvri.gov.tw.
authors.forename: Yu-Liang
authors.initials: YL
authors.lastname: Huang
authors.affiliation: Animal Health Research Institute, Council of Agriculture, Executive Yuan, 376 Chung-Cheng Road, Tansui, New Taipei City, 25158, Taiwan. Electronic address: mcdeng@mail.nvri.gov.tw.
authors.forename: Ming-Chung
authors.initials: MC
authors.lastname: Deng
authors.affiliation: Animal Health Research Institute, Council of Agriculture, Executive Yuan, 376 Chung-Cheng Road, Tansui, New Taipei City, 25158, Taiwan. Electronic address: krtsai@mail.nvri.gov.tw.
authors.forename: Kuo-Jung
authors.initials: KJ
authors.lastname: Tsai
authors.affiliation: Animal Health Research Institute, Council of Agriculture, Executive Yuan, 376 Chung-Cheng Road, Tansui, New Taipei City, 25158, Taiwan. Electronic address: casiopea963@yahoo.com.tw.
authors.forename: Hsin-Meng
authors.initials: HM
authors.lastname: Liu
authors.affiliation: Council of Agriculture, Executive Yuan, No. 37 Nanhai Road, Taipei, 10014, Taiwan. Electronic address: cch@mail.coa.gov.tw.
authors.forename: Chin-Cheng
authors.initials: CC
authors.lastname: Huang
authors.affiliation: School of Veterinary Medicine, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei, 10617, Taiwan. Electronic address: fiwangvm@ntu.edu.tw.
authors.forename: Fun-In
authors.initials: FI
authors.lastname: Wang
authors.affiliation: Animal Health Research Institute, Council of Agriculture, Executive Yuan, 376 Chung-Cheng Road, Tansui, New Taipei City, 25158, Taiwan. Electronic address: cychang@mail.nvri.gov.tw.
authors.forename: Chia-Yi
authors.initials: CY
authors.lastname: Chang
mesh_terms: D000818:Animals; D002460:Cell Line; D006691:Classical Swine Fever / Q000175:diagnosis / Q000821:virology*; D006692:Classical Swine Fever Virus / Q000472:pathogenicity / Q000502:physiology*; D014644:Genetic Variation; D005838:Genotype; D007700:Kinetics; D013552:Swine; D063189:Symptom Assessment; D019562:Viral Load; D053585:Virus Attachment; D014779:Virus Replication
keywords: Classical swine fever virus; Genotype; Pathogenesis; Viral replication; Virus shift