Researchers from Spain's Centre for animal health research, CReSA, in Barcelona have demonstrated that protecting pigs against African swine fever is not science fiction. This conclusion follows a study recently published in the journal, PLoS One. African swine fever virus (ASFV) is in continuous expansion since its appearance in Europe through Georgia in 2007.

African Swine Fever (ASF) is a disease of domestic pigs caused by African Swine Fever Virus (ASFV). The fact that the disease is endemic in Sardinia and overall, in many Sub-Saharan African countries, where it causes important loses, provoked the return of the virus to Europe through Republic of Georgia in 2007. Since then, the virus has continued its expansion through adjacent countries, including Russia, where the situation remains uncontrolled nowadays.

The lack of available vaccines against ASFV complicates even more the control of the disease. Therefore, developing an efficient and safe vaccine against ASF is a must.

The latest results obtained by the research group from CReSA clearly demonstrate the possibility of protecting pigs against a lethal ASFV challenge by using DNA vaccines encoding three of the viral antigens (ASFV encodes more than 150 different proteins). Moreover, the relevance of the CD8+ T-cells - a lymphocyte subset capable to recognise infected cells and specifically destroy them - in protection, has been definitively confirmed.

Dr Fernando Rodríguez, principal investigator of this research line explained the results: "Our initial work was based on preliminary studies performed in the mid-90s, demonstrating the immunogenic properties of three ASFV proteins: p54, p30 and haemagglutinin (HA).

"In our study, we have been able to demonstrate that DNA vaccines (in the form of innocuous DNA plasmid molecules) encoding these three viral antigens, are capable to provoke a significant delay on the death of the animals after ASFV lethal challenge and more importantly, that 33 per cent of the immunised pigs survive and totally recovered from the infection.

"To achieve this protection, optimising the presentation of the vaccine encoded antigens to the specific CD8+ T-cells by ubiquitination (i.e. a label that marks proteins for intracellular degradation), was mandatory. In fact, the protection conferred totally correlated with the presence of large number of specific CD8+ T-cells in the blood of surviving pigs with no need of antibodies-help."

This research group is currently in the process of characterising new viral antigens (within the rest of the ASFV 150 proteins) with potential to provoke protective CD8+ T-cell responses.

Dr Rodríguez continued: "The final objective of our work is finding an optimal vaccine formulation capable to protect the haplotype-diversity found in our conventional pig farms. It will not be an easy task but certainly we believe that it could be feasible."

The results of this study were published in 2012.

Reference

Argilaguet J.M., Pérez-Martín E., Nofrarías M., Gallardo C., Accensi F., Lacasta A., Mora M., Ballester M., Galindo-Cardiel I., López-Soria S., Escribano J.M., Reche P.A. and Rodríguez F. 2012. DNA vaccination partially protects against African Swine Fever virus lethal challenge in the absence of nntibodies. PLoS One. 2012;7(9):e40942. doi: 10.1371/journal.pone.0040942.

Further Reading You can view the full research paper by clicking here. For more information on African Swine Fever, click here.