Enhancing DNA immunization by targeting ASFV antigens to SLA-II bearing cells.

Area of Science:

• Veterinary Immunology
• Molecular Biology
• Vaccinology

Background:

• DNA vaccines often show poor immunogenicity in large animals, including pigs.
• A plasmid DNA vaccine (pCMV-PQ) encoding African swine fever virus (ASFV) genes failed to elicit immune responses in pigs, unlike in mice.

Purpose of the Study:

• To enhance immune responses in pigs against ASFV using DNA vaccination.
• To investigate the efficacy of targeting antigens to antigen-presenting cells (APCs) in swine.

Main Methods:

• Construction of a novel DNA vaccine (pCMV-APCH1PQ) encoding ASFV genes fused to a single-chain variable fragment targeting swine leukocyte antigen II (SLA II).
• Immunization of pigs with pCMV-APCH1PQ and assessment of immune responses.
• Evaluation of vaccine efficacy through lethal ASFV challenge.

Main Results:

• Targeting antigens to APCs significantly enhanced immune responses in pigs compared to the non-targeted vaccine.
• Despite enhanced immune responses, the vaccine did not confer protection against lethal ASFV challenge.
• Viremia exacerbation was observed in vaccinated pigs, correlated with non-neutralizing antibodies and SLA II-restricted T-cell responses.

Conclusions:

• Targeting antigens to APCs is a viable strategy to boost DNA vaccine immunogenicity in pigs.
• Further research is needed to develop protective vaccines against ASFV, potentially by improving antigen presentation or inducing neutralizing antibodies.
• These findings have implications for developing vaccines against ASFV and other swine pathogens.