African swine fever virus I196L is a virulence determinant and its deletant induces robust protection in Domestic pig

Abstract

The worldwide pandemic of African swine fever virus (ASFV) has a profound impact on the global pig industry. ASFV is a complex multilayered structure and the functions of unknown genes are being revealed. Here we deleted I196L from virulent ASFV SY18 with different length and obtained two recombinant viruses. The replication efficiency of the two recombinant viruses were similar but significantly lower than parental SY18. The pigs all survived the two recombinant viruses with 106.0TCID50except one pig occurred sudden death and the suvived pigs all resisted the challenge without fever after intramuscularly injecting a lethal dose (102.0TCID50) of ASFV SY18. The recombinant viruses induced a strong anti-p54 humoral immune response. Meanwhile, the pigs also inevitably appeared moderate to high viremia throughout the observation period and presented a gradually downward trend. The results show that deleting I196L gene is a potential and effective vaccine that protects pigs from ASFV.

A Whole-Genome Analysis of the African Swine Fever Virus That Circulated during the First Outbreak in Vietnam in 2019 and Subsequently in 2022

“…In the present study, the results of the multiple sequence alignment analysis for 28 ORFs, particularly EP153R, I196L, KP177R, and MGFs of VN/HY/2019-ASFV1 and VN/QP/2019-ASFV1, showed distinct deletion regions compared to Estonia 2014 and the p72 genotype I strains. Mutations observed in EP153R, I196L, and KP177R are associated with increased virulence and transmissivity, potentially rendering the ASFV less susceptible to vaccines [ 37 , 38 , 39 ]. Moreover, three MGFs (MGF110, MGF360, and MGF505) of VN/HY/2019-ASFV1 and VN/QP/2019-ASFV1 displayed the most similarity at the 5′ and 3′ ends of the variable region with the p72 genotype II strains and showed more modifications and gene deletions than p72 genotype I strains.…”

“…Compared to a highly pathogenic ASFV strain, the non-pathogenic isolate lacked eight MGF genes (MGF505-1R and MGF360-9L, 10L, 11L, 12L, 13L, 14L, and 2R), suggesting that MGF505 and MGF360 may play important roles in virulence and immune evasion [ 42 ]. The recent VN/HY2022-ASFV2 strain had a 99.98% ANI compared to VN/HY/2019-ASFV1 and VN/QP/2019-ASFV1 and showed variations in 16 ORFs, particularly with numerous mutations in MGF360-21R, I196L, and H233R ORFs, which are involved in virulence and transmission [ 38 , 43 ]. However, it remains unclear whether the diversity observed in EP153R, I196L, KP177R, I996L, H233R, and MGF in Vietnamese strains affects the virulence, viral transmissibility, and susceptibility to vaccines of the currently circulating Vietnamese ASFV, warranting further investigations.…”