Recombinant CSFV E2 Protein [His]

In this short report, the genome-wide homologous recombination events were re-evaluated for classical swine fever virus (CSFV) strain AF407339. We challenged a previous study which suggested only one recombination event in AF407339 based on 25 CSFV genomes. Through our re-analysis on the 25 genomes in the previous study and the 41 genomes used in the present study, we argued that there should be possibly at least two clear recombination events happening in AF407339 through genome-wide scanning. The reasons for identifying only one recombination event in the previous study might be due to the limited number of available CSFV genome sequences at that time and the limited usage of detection methods. In contrast, as identified by most detection methods using all available CSFV genome sequences, two major recombination events were found at the starting and ending zones of the genome AF407339, respectively. The first one has two parents AF333000 (minor) and AY554397 (major) with beginning and ending breakpoints located at 19 and 607 nt of the genome respectively. The second one has two parents AF531433 (minor) and GQ902941 (major) with beginning and ending breakpoints at 8397 and 11,078 nt of the genome respectively. Phylogenetic incongruence analysis using neighbor-joining algorithm with 1000 bootstrapping replicates further supported the existence of these two recombination events. In addition, we also identified additional 18 recombination events on the available CSFV strains. Some of them may be trivial and can be ignored. In conclusion, CSFV might have relatively high frequency of homologous recombination events. Genome-wide scanning of identifying recombination events should utilize multiple detection methods so as to reduce the risk of misidentification. (C) 2014 Production and hosting by Elsevier B.V. on behalf of King Saud University.

Here, we examined the pathogenicity and genetic differences between classical swine fever viruses (CSFV) isolated on pig farms in North Vietnam from 2014-2018. Twenty CSFV strains from 16 pig farms were classified as genotype 2 (sub-genotypes 2.1b, 2.1c, and 2.2). The main sub-genotype, 2.1c, was classified phylogenetically as belonging to the same cluster as viruses isolated from the Guangdong region in South China. Strain HY58 (sub-genotype 2.1c), isolated from pigs in Vietnam, caused higher mortality (60%) than the Vietnamese ND20 strain (sub-genotype 2.2). The Vietnamese strain of sub-genotype 2.1b was estimated to have moderate virulence; indeed, genetic analysis revealed that it belongs to the same cluster as Korean CSFV sub-genotype 2.1b. Most CSFVs circulating in North Vietnam belong to sub-genotype 2.1c. Geographical proximity means that this genotype might continue to circulate in both North Vietnam and Southern China (Guangdong, Guangxi, and Hunan).