AUTHOR=Fan Jiaqi , Zhang Jingyuan , Wang Fengjie , Miao Faming , Zhang Han , Jiang Yiqian , Qi Yu , Zhang Yanyan , Hui Lili , Zhang Dan , Yue Huixian , Zhou Xintao , Li Qixuan , Wang Yu , Chen Teng , Hu Rongliang 

TITLE=Identification of L11L and L7L as virulence-related genes in the African swine fever virus genome

JOURNAL=Frontiers in Microbiology

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2024.1345236

DOI=10.3389/fmicb.2024.1345236

ISSN=1664-302X

ABSTRACT=<sec><title>Introduction</title><p>African swine fever (ASF) is an infectious disease that causes considerable economic losses in pig farming. The agent of this disease, African swine fever virus (ASFV), is a double-stranded DNA virus with a capsid membrane and a genome that is 170-194 kb in length encoding over 150 proteins. In recent years, several live attenuated strains of ASFV have been studied as vaccine candidates, including the SY18ΔL7-11. This strain features deletion of <italic>L7L</italic>, <italic>L8L</italic>, <italic>L9R</italic>, <italic>L10L</italic> and <italic>L11L</italic> genes and was found to exhibit significantly reduced pathogenicity in pigs, suggesting that these five genes play key roles in virulence.</p></sec><sec><title>Methods</title><p>Here, we constructed and evaluated the virulence of ASFV mutations with SY18ΔL7, SY18ΔL8, SY18ΔL9, SY18ΔL10, and SY18ΔL11L.</p></sec><sec><title>Results</title><p>Our findings did not reveal any significant differences in replication efficiency between the single-gene deletion strains and the parental strains. Pigs inoculated with SY18ΔL8L, SY18ΔL9R and SY18ΔL10L exhibited clinical signs similar to those inoculated with the parental strains. Survival rate of pigs inoculated with 10<sup>3.0</sup>TCID<sub>50</sub> of SY18ΔL7L was 25%, while all pigs inoculated with 10<sup>3.0</sup>TCID<sub>50</sub> of SY18ΔL11L survived, and 50% inoculated with 10<sup>6.0</sup>TCID<sup>50</sup> SY18ΔL11L survived.</p></sec><sec><title>Discussion</title><p>The results indicate that <italic>L8L</italic>, <italic>L9R</italic> and <italic>L10L</italic> do not affect ASFV SY18 virulence, while the <italic>L7L</italic> and <italic>L11L</italic> are associated with virulence.</p></sec>