Sequencing and rescuing a highly virulent classical swine fever virus: Chinese strain cF114 from a full-length cDNA clone

2003 ◽  
Vol 48 (11) ◽  
pp. 1124-1128 ◽  
Author(s):  
Yuchun Nie ◽  
Jianguo Chen ◽  
Mingxiao Ding
Keyword(s):  
Cdna Clone ◽  
Classical Swine Fever Virus ◽  
Classical Swine Fever ◽  
Fever Virus ◽  
Full Length ◽  
Chinese Strain ◽  
Full Length Cdna ◽  
Highly Virulent

scholarly journals Analysis of Virus Population Profiles within Pigs Infected with Virulent Classical Swine Fever Viruses: Evidence for Bottlenecks in Transmission but Absence of Tissue-Specific Virus Variants

2020 ◽  
Vol 94 (19) ◽  
Author(s):  
Camille Melissa Johnston ◽  
Ulrik Fahnøe ◽  
Louise Lohse ◽  
Jens Bukh ◽  
Graham J. Belsham ◽  
...  
Keyword(s):  
Classical Swine Fever Virus ◽  
Population Change ◽  
Virulent Strain ◽  
Severe Disease ◽  
Clinical Signs ◽  
Classical Swine Fever ◽  
Fever Virus ◽  
Host Cells ◽  
Virus Population ◽  
Highly Virulent

ABSTRACT Classical swine fever virus (CSFV) contains a specific motif within the E2 glycoprotein that differs between strains of different virulence. In the highly virulent CSFV strain Koslov, this motif comprises residues S763/L764 in the polyprotein. However, L763/P764 represent the predominant alleles in published CSFV genomes. In this study, changes were introduced into the CSFV strain Koslov (here called vKos_SL) to generate modified CSFVs with substitutions at residues 763 and/or 764 (vKos_LL, vKos_SP, and vKos_LP). The properties of these mutant viruses, in comparison to those of vKos_SL, were determined in pigs. Each of the viruses was virulent and induced typical clinical signs of CSF, but the vKos_LP strain produced them significantly earlier. Full-length CSFV cDNA amplicons (12.3 kb) derived from sera of infected pigs were deep sequenced and cloned to reveal the individual haplotypes that contributed to the single-nucleotide polymorphism (SNP) profiles observed in the virus population. The SNP profiles for vKos_SL and vKos_LL displayed low-level heterogeneity across the entire genome, whereas vKos_SP and vKos_LP displayed limited diversity with a few high-frequency SNPs. This indicated that vKos_SL and vKos_LL exhibited a higher level of fitness in the host and more stability at the consensus level, whereas several consensus changes were observed in the vKos_SP and vKos_LP sequences, pointing to adaptation. For each virus, only a subset of the variants present within the virus inoculums were maintained in the infected pigs. No clear tissue-dependent quasispecies differentiation occurred within inoculated pigs; however, clear evidence for transmission bottlenecks to contact animals was observed, with subsequent loss of sequence diversity. IMPORTANCE The surface-exposed E2 protein of classical swine fever virus is required for its interaction with host cells. A short motif within this protein varies between strains of different virulence. The importance of two particular amino acid residues in determining the properties of a highly virulent strain of the virus has been analyzed. Each of the different viruses tested proved highly virulent, but one of them produced earlier, but not more severe, disease. By analyzing the virus genomes present within infected pigs, it was found that the viruses which replicated within inoculated animals were only a subset of those within the virus inoculum. Furthermore, following contact transmission, it was shown that a very restricted set of viruses had transferred between animals. There were no significant differences in the virus populations present in various tissues of the infected animals. These results indicate mechanisms of virus population change during transmission between animals.

scholarly journals P108 and T109 on E2 Glycoprotein Domain I Are Critical for the Adaptation of Classical Swine Fever Virus to Rabbits but Not for Virulence in Pigs

2020 ◽  
Vol 94 (17) ◽  
Author(s):  
Libao Xie ◽  
Yuying Han ◽  
Yuteng Ma ◽  
Mengqi Yuan ◽  
Weike Li ◽  
...  
Keyword(s):  
Viral Entry ◽  
Classical Swine Fever Virus ◽  
Molecular Basis ◽  
Classical Swine Fever ◽  
Fever Virus ◽  
E2 Glycoprotein ◽  
Viral Adaptation ◽  
Glycoprotein E2 ◽  
Domain I ◽  
Highly Virulent

ABSTRACT The classical swine fever virus (CSFV) live attenuated vaccine C-strain is adaptive to rabbits and attenuated in pigs, in contrast with the highly virulent CSFV Shimen strain. Previously, we demonstrated that P108 and T109 on the E2 glycoprotein (E2P108-T109) in domain I (E2DomainI) rather than R132, S133, and D191 in domain II (E2DomainII) determine C-strain’s adaptation to rabbits (ATR) (Y. Li, L. Xie, L. Zhang, X. Wang, C. Li, et al., Virology 519:197–206, 2018). However, it remains elusive whether these critical amino acids affect the ATR of the Shimen strain and virulence in pigs. In this study, three chimeric viruses harboring E2P108-T109, E2DomainI, or E2DomainII of C-strain based on the non-rabbit-adaptive Shimen mutant vSM-HCLVErns carrying the Erns glycoprotein of C-strain were generated and evaluated. We found that E2P108-T109 or E2DomainI but not E2DomainII of C-strain renders vSM-HCLVErns adaptive to rabbits, suggesting that E2P108-T109 in combination with the Erns glycoprotein (E2P108-T109-Erns) confers ATR on the Shimen strain, creating new rabbit-adaptive CSFVs. Mechanistically, E2P108-T109-Erns of C-strain mediates viral entry during infection in rabbit spleen lymphocytes, which are target cells of C-strain. Notably, pig experiments showed that E2P108-T109-Erns of C-strain does not affect virulence compared with the Shimen strain. Conversely, the substitution of E2DomainII and Erns of C-strain attenuates the Shimen strain in pigs, indicating that the molecular basis of the CSFV ATR and that of virulence in pigs do not overlap. Our findings provide new insights into the mechanism of adaptation of CSFV to rabbits and the molecular basis of CSFV adaptation and attenuation. IMPORTANCE Historically, live attenuated vaccines produced by blind passage usually undergo adaptation in cell cultures or nonsusceptible hosts and attenuation in natural hosts, with a classical example being the classical swine fever virus (CSFV) lapinized vaccine C-strain, which was developed by hundreds of passages in rabbits. However, the mechanism of viral adaptation to nonsusceptible hosts and the molecular basis for viral adaptation and attenuation remain largely unknown. In this study, we demonstrated that P108 and T109 on the E2 glycoprotein together with the Erns glycoprotein of the rabbit-adaptive C-strain confer adaptation to rabbits on the highly virulent CSFV Shimen strain by affecting viral entry during infection but do not attenuate the Shimen strain in pigs. Our results provide vital information on the different molecular bases of CSFV adaptation to rabbits and attenuation in pigs.

scholarly journals Improved strategy for phylogenetic analysis of classical swine fever virus based on full-length E2 encoding sequences

2012 ◽  
Vol 43 (1) ◽  
pp. 50 ◽  
Author(s):  
Alexander Postel ◽  
Stefanie Schmeiser ◽  
Jennifer Bernau ◽  
Alexandra Meindl-Boehmer ◽  
Gediminas Pridotkas ◽  
...  
Keyword(s):  
Phylogenetic Analysis ◽  
Classical Swine Fever Virus ◽  
Classical Swine Fever ◽  
Fever Virus ◽  
Full Length

Analysis of classical swine fever virus replication kinetics allows differentiation of highly virulent from avirulent strains

2000 ◽  
Vol 74 (4) ◽  
pp. 293-308 ◽  
Author(s):  
Christian Mittelholzer ◽  
Christian Moser ◽  
Jon-Duri Tratschin ◽  
Martin A Hofmann
Keyword(s):  
Virus Replication ◽  
Classical Swine Fever Virus ◽  
Classical Swine Fever ◽  
Fever Virus ◽  
Highly Virulent
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