Hans Nauwynck
Ghent University
Merelbeke, Belgium


``Driving biological forces behind the evolution of PCV2 in swine``

FRIDAY, JUNE 2, 2023


Hans Nauwynck is a DVM, who did his PhD and directly became nominated as professor at Ghent University in 1993. In 2004, he took the lead of the Laboratory of Virology, Faculty of Veterinary Medicine, Ghent University and became Diplomate at the European College of Pig Health Management. At present, he lectures several courses on viral diseases in mammals, fish and shellfish. His research focuses on the cellular and molecular pathogenesis of viral diseases in humans and animals, with special emphasis on (i) the entry of the virus in its host cell, (ii) the invasion of the virus in its host through barriers, via leukocytes and along neurons and (iii) the escape of the virus from immunity. Better insights led to the development of new diagnostics, better viral disease control measures and tailor-made vaccines. He is (co-)author of 423 peer reviewed papers, past promoter of 75 PhDs, owner of 12 patents and founder of two spin-offs (Imaqua & Pathosense). He is a regular invited speaker at international congresses.


Porcine circovirus type 2 is a very small DNA virus that is already circulating in pigs for a very long time. As the virus does not have its own DNA dependent DNA polymerase, it hijacks it from mitotic target cells, such as lymphoblasts and fetal cells. During the last decades, the intensification of pig husbandry is facilitating circulation of a lot of pathogens in swine herds, which in turn strongly stimulates the blastogenesis. The continuous presence of a huge number of lymphoblasts boosts the replication of PCV2 (and also other small DNA viruses that are host DNA polymerase-dependent) in its host, leading to PCV2-associated diseases. In addition, genetic selection in the direction of fast growing and highly productive pigs led to a better growth of PCV2 in lymphoblasts and to a lower elimination by monocytes. A logical consequence of this increased PCV2 replication is an augmented mutation rate and an accelerated evolution. Following the law of the fittest, the virus is adapting to a better replication in lymphoblasts. One beautiful example is the improvement of its binding to the cellular receptor. Next to this, the population immunity may drive the virus in the direction of immune-escaping variants. In conclusion, modern husbandry and animal breeding has given PCV2 the opportunity to become an important pathogen in swine and adaptation for a better replication in lymphoblasts and escape from immunity is shaping the PCV2 variants of the future.