SY18ΔL60L: a new recombinant live attenuated African swine fever virus with protection against homologous challenge

Jinjin Yang; Rongnian Zhu; Yanyan Zhang; Jiaqi Fan; Xintao Zhou; Huixian Yue; Qixuan Li; Faming Miao; Teng Chen; Lijuan Mi; Fei Zhang; Shoufeng Zhang; Aidong Qian; Rongliang Hu

doi:10.3389/fmicb.2023.1225469

SY18ΔL60L: a new recombinant live attenuated African swine fever virus with protection against homologous challenge

Front Microbiol. 2023 Aug 9:14:1225469. doi: 10.3389/fmicb.2023.1225469. eCollection 2023.

Authors

Jinjin Yang^{1

2

3}, Rongnian Zhu^{2

3}, Yanyan Zhang^{2

3}, Jiaqi Fan⁴, Xintao Zhou⁴, Huixian Yue^{2

3}, Qixuan Li¹, Faming Miao^{2

3}, Teng Chen^{2

3}, Lijuan Mi^{2

3}, Fei Zhang^{2

3}, Shoufeng Zhang^{2

3}, Aidong Qian¹, Rongliang Hu^{2

3}

Affiliations

¹ College of Veterinary Medicine, Jilin Agricultural University, Changchun, China.
² Changchun Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Changchun, China.
³ Key Laboratory of Prevention & Control for African Swine Fever and Other Major Pig Diseases, Ministry of Agriculture and Rural Affairs, Changchun, China.
⁴ Life Science College, Ningxia University, Yinchuan, China.

Abstract

Introduction: African swine fever (ASF) is an acute and highly contagious disease and its pathogen, the African swine fever virus (ASFV), threatens the global pig industry. At present, management of ASF epidemic mainly relies on biological prevention and control methods. Moreover, due to the large genome of ASFV, only half of its genes have been characterized in terms of function.

Methods: Here, we evaluated a previously uncharacterized viral gene, L60L. To assess the function of this gene, we constructed a deletion strain (SY18ΔL60L) by knocking out the L60L gene of the SY18 strain. To evaluate the growth characteristics and safety of the SY18ΔL60L, experiments were conducted on primary macrophages and pigs, respectively.

Results: The results revealed that the growth trend of the recombinant strain was slower than that of the parent strain in vitro. Additionally, 3/5 (60%) pigs intramuscularly immunized with a 105 50% tissue culture infectious dose (TCID50) of SY18ΔL60L survived the 21-day observation period. The surviving pigs were able to protect against the homologous lethal strain SY18 and survive. Importantly, there were no obvious clinical symptoms or viremia.

Discussion: These results suggest that L60L could serve as a virulence- and replication-related gene. Moreover, the SY18ΔL60L strain represents a new recombinant live-attenuated ASFV that can be employed in the development of additional candidate vaccine strains and in the elucidation of the mechanisms associated with ASF infection.

Keywords: African swine fever virus; L60L; attenuated virus; deleted; recombinant virus.