Extracellular vesicles represent a new vaccination strategy against a porcine virus

A study led by Hernando A. del Portillo, ICREA researcher at ISGlobal and IGTP, performs the first molecular characterization of extracellular vesicles isolated from animals previously infected with the porcine respiratory and reproductive virus (PRRSV) and shows that such vesicles (exosomes) are free of viruses but contain viral proteins that can be recognized by the immune system. The results indicate that exosomes represent a new alternative vaccination strategy to control, and eventually eradicate, PRRSV.

Over the last years, Dr. del Portillo’s group has studied exosomes (cell-derived vesicles present in almost any bodily fluid) and their potential use as vaccines. Studies performed by his and other groups show that exosomes contain proteins from tumours or infectious agents, including the malaria parasite, and can induce strong immune responses. On the other hand, PRRSV causes one of the most important swine diseases, with a significant economic burden worldwide. In the USA alone, it is responsible for more than 500 million USD losses every year. Available vaccines against the virus have several limitations, such as the induction of a poor and short-lasting immune response and the lack of cross-protection against the different genotypes (European and American).

Therefore, the authors decided to characterize and compare the exosomes isolated from the sera of PRRSV-infected (viremic) animals, previously infected but no longer viremic animals, or non-infected animals. They found that exosomes obtained from the serum of previously infected animals are free of virus but contain viral proteins that are recognized by antibodies against the virus. In addition, the authors describe a process to scale-up the production of these vesicles, to facilitate future vaccination studies. “This is the first characterization of exosomes from pigs with active versus previous infection with PRRSV” comments Dr. del Portillo, “and the results suggest their use as a novel vaccine approach against the virus”.

This study is part of an Industrial PhD (Sergio Montaner-Tarbes) funded by AGAUR in a joint agreement between the University of Lleida (Lorenzo Fraile) and the INNOVEX THERAPEUTICS S.L. Spin-off, of which H. del Portillo is a founding member. Researchers (Maria Montoya) from the Pirbright Institute UK and Francesc E. Borrás from the Instituto German Trias i Pujol also participated in the study.