Live-vectored antigen cocktail confers protection against African swine fever virus (ASFV) Georgia 2007/1 challenge.

African swine fever (ASF) is a lethal disease of swine caused by the ASF virus (ASFV), for which no licensed vaccine is currently available in non-endemic countries. Here, replication-competent adenovirus-vectored ASFV multi-antigen constructs were shown to express ASFV antigens in primary swine cells. Pigs immunized with a cocktail of these constructs, with or without Quil-A adjuvant, tolerated the formulation well. The constructs elicited robust ASFV-specific IgG responses (p < 0.0001), which were boosted upon reimmunization (p < 0.05). Following challenge with the virulent ASFV Georgia 2007/1 strain using a natural transmission model, five of six pigs vaccinated without Quil-A survived, while all pigs receiving adjuvanted constructs succumbed to ASF. Survivors cleared the virus, exhibited only mild clinical signs, gained weight, and remained healthy for the remainder of the study. Histopathological analysis revealed an absence of ASFV-associated lesions in survivors, whereas severe lesions were observed in pigs vaccinated with adjuvanted constructs and in negative controls. Although neutralizing antibodies were undetectable, granzyme B-producing CD8α⁺ T cell responses were observed in survivors, indicating a likely correlation for cellular immunity in protection. These findings highlight the protective potential of ASFV antigen expression constructs and inform subunit vaccine design.

Kansas State University