Evaluation of an I177L gene-based five-gene-deleted African swine fever virus as a live attenuated vaccine in pigs

Abstract

African swine fever (ASF) is a highly contagious disease of domestic and wild pigs caused by the African swine fever virus (ASFV). The current research on ASF vaccines focuses on the development of naturally attenuated, isolated, or genetically engineered live viruses that have been demonstrated to produce reliable immunity. As a result, a genetically engineered virus containing five genes deletion was synthesized based on ASFV Chinese strain GZ201801, named ASFV-GZΔI177LΔCD2vΔMGF. The five-gene-deleted ASFV was safe and fully attenuated in pigs and provides reliable protection against the parental ASFV strain challenge. This indicates that the five-gene-deleted ASFV is a potential candidate for a live attenuated vaccine that could control the spread of ASFV.

Combinational Deletions of MGF110-9L and MGF505-7R Genes from the African Swine Fever Virus Inhibit TBK1 Degradation by an Autophagy Activator PIK3C2B To Promote Type I Interferon Production

“…Of these, LAVs (ASFV-GZ-ΔI177L, HLJ/18-7GD, SY18ΔI226R, and ASFV-G-ΔA137R, etc.) ( 25 , 29 , 41 – 43 ) are the only vaccines that induce 100% immune protection against parental ASFV challenge. However, LAVs carry the risk of virus shedding and field virus recombination ( 29 ), which is a huge biosecurity challenge and threat for long-term ASF prevention and control.…”

“…Some other ASFV genes also play pivotal roles in regulating host antiviral response and viral replication and are considered effective live attenuated vaccine (LAV) candidate targets, such as I177L ( 21 ), B119L ( 22 ), DP96R ( 23 ), EP402R ( 24 ), I226R ( 25 ), A137R ( 26 ), and E184L ( 27 ). Of these, ASFV-G-ΔI177L offers 100% protection of pigs against the epidemiologically lethal ASFV Georgia isolate challenge ( 21 , 28 ), but the biosecurity risks of ASFV-G-ΔI177L in domestic pigs, especially in intensive pig farms, cannot be completely excluded ( 29 ).…”

“…According to the experience and understanding of previous studies, gene-deleted live attenuated vaccines of ASFV are still the most effective vaccine candidates to prevent ASF. However, stacks of research papers have suggested that deletion of a single gene is insufficient to attenuate the virulence of virus and against challenge of parental ASFV ( 29 ). Recently, our laboratory has reported that the live attenuated ASFV-Δ110-9L/505-7R provided complete protection against parental ASFV challenge.…”

Saccharomyces cerevisiae oral immunization in mice using multi-antigen of the African swine fever virus elicits a robust immune response

“…Additionally, the use of adjuvants did not improve the efficiency of ASFV-inactivated vaccines ( 13 ). ASFV vaccines are typically produced from live attenuated viruses, protein subunits, or recombinant vectors ( 14 , 15 ). Live attenuated ASFV vaccines require robust safety testing, before being considered safe for widespread use ( 16 – 19 ).…”

Evaluation of humoral and cellular immune responses induced by a cocktail of recombinant African swine fever virus antigens fused with OprI in domestic pigs

“…Vaccines containing inactivated viruses have not conferred protection so far [ 10 ]. Attenuated or low virulent ASFV strains have been demonstrated to elicit protective immune responses against virulent ASFV strains in swine [ 11 – 14 ] but, the vaccinated pigs usually experience adverse side effects, such as chronic viremia [ 15 ]. Furthermore, the application of live attenuated ASFV raises serious concerns of safety.…”