Serum-derived extracellular vesicles from African swine fever virus-infected pigs selectively recruit viral and porcine proteins

African swine fever is a devastating hemorrhagic infectious disease, which a ects domestic and wild swines (Sus scrofa) of all breeds and ages, with a high lethality of up to 90–100% in naïve animals. The causative agent, African swine fever virus (ASFV), is a large and complex double-strandedDNA arbovirus which is currently spreading worldwide, with serious socioeconomic consequences. There is no treatment or e ective vaccine commercially available, and most of the current research is focused on attenuated viralmodels, with limited success so far. Thus, new strategies are under investigation. Extracellular vesicles (EVs) have proven to be a promising new vaccination platform for veterinary diseases in situations in which conventional approaches have not been completely successful. Here, serum extracellular vesicles from infected pigs using two di erent ASFV viruses (OURT 88/3 and Benin DMGF), corresponding to a naturally attenuated virus and a deletion mutant, respectively, were characterized in order to determine possible di erences in the content of swine and viral proteins in EV-enriched fractions. Firstly, EVs were characterized by their CD5, CD63, CD81 and CD163 surface expression. Secondly, ASFV proteins were detected on the surface of EVs from ASFV-infected pig serum. Finally, proteomic analysis revealed few specific proteins from ASFV in the EVs, but 942 swine proteins were detected in all EV preparations (negative controls, and OURT 88/3 and Benin DMGF-infected preparations). However, in samples from OURT 88/3-infected animals, only a small number of proteins were di erentially identified compared to control uninfected animals. Fifty-six swine proteins (Group Benin) and seven proteins (Group OURT 88/3) were di erentially detected on EVs when compared to the EV control group. Most of these were related to coagulation cascades. The results presented here could contribute to a better understanding of ASFV pathogenesis and immune/protective responses in the host.

Sergio Montaner Tarbes was funded by an Industrial PhD Fellowship by Doctorats Industrials de Catalonia (Agència de Gestió d’Ajuts Universitaris i de Recerca). This article is based upon work from COST Action CA15116 ASF-STOP, supported by COST (European Cooperation in Science and Technology) and the UK’s BBSRC grants BBS/E/I/00002014 and BB/L004267/1.