ABSTRACT African swine fever virus (ASFV) causes a lethal hemorrhagic disease in domestic pigs, wild boar, and other members of the genus Sus . Since the introduction of the virus into Georgia in 2007, the disease has spread across Eurasia causing the deaths of millions of animals and the production loss of more than 100 million with a significant socioeconomic impact. Modified live virus vaccines have been licensed and tested in several countries, but there are some residual safety concerns and the efficacy in the field is yet to be established. A subunit vaccine would provide a significant biosafety advantage and avoid the use of live African swine fever virus and would enable deployment of a simple distinguish infected from vaccinated animals (DIVA) strategy. However, the development of effective subunit vaccines has been slow due in part to the complexity of the virus and a poor understanding of the protective immune response. A pool of six viral genes vectored using replication-deficient adenoviruses could protect pigs against genotype I challenge; however, a combination of vectors partially tailored to genotype II ASFV was not successful after a genotype II challenge. Here, we provide immunogenicity and challenge data from a study using genotype II ASFV genes vectored using replication-deficient simian adenoviruses. The six antigens previously shown to protect against severe disease caused by genotype I challenge were supplemented with additional antigens, but these were not sufficient to prevent clinical disease after challenge with genotype II ASFV. IMPORTANCE African swine fever is a viral hemorrhagic disease of domestic and wild pigs that poses a significant threat to farmers and global food security. Millions of animals have been lost due to the disease itself, control measures, and the knock-on effect on the pig production chain. African swine fever is also a conservation risk as it infects and kills endangered indigenous pigs in southern and eastern Asia and Oceania. Disease control efforts are in part frustrated by the lack of a safe and effective vaccine. Modified live virus vaccines are being deployed in select countries; however, a subunit vaccine like those developed for COVID would alleviate safety concerns with using live viruses in the field. We tested a combination of eight different virus genes delivered using replication-deficient adenoviruses and showed that they induced immune responses in pigs but did not lead to protection against disease.
Tng et al. (Fri,) studied this question.