In his comprehensive review published in Veterinary Pathology, Professor John Ellis of the Western College of Veterinary Medicine at the University of Saskatchewan, Canada, explains that porcine circoviruses (PCVs) belong to the genus Circovirus and the family Circoviridae, and they are the smallest known viruses that replicate autonomously in mammalian cells.

They are non-enveloped, and they have characteristic single-stranded, negative-sense, circular DNA.

Two types of divergent PCVs are recognised: PCV1 and PCV2. About 20 years ago, PCV2 began to emerge as a major pathogen of swine around the world, leading to burgeoning knowledge about the virus and porcine circovirus–associated diseases (PCVAD). However, much of the history of its discovery, including the controversy related to its importance, is not recorded.

Dr Ellis's review examines current issues related to the biology of PCV2 in the context of the original studies related to determining its causal association with disease and to the evolving understanding of the complex pathogenesis of PCV2 infections.

The author's closing remarks are as follows:

From an investigator’s standpoint, the circovirus story is really one of rare privilege and good fortune and, thus, a truly humbling experience: a privilege to see the biology of a new infectious disease and the investigation thereof play out on a world stage and, at the end of the day, a privilege to be left in a state of wonderment.

Then there is the best of fortune – or, rather, in many ways, just plain dumb luck – manifested as rare instances of stellar alignment: a convergence of astute clinicians, a persistent diagnostic pathologist, dedicated technicians, and a major biologics firm that took a big risk on a small group of unruly, less-than-conventional investigators with no real presence in one of its major product areas – and, of course, the bug, the host, and the environment in just the right state of flux for something really big to happen.

Together, this sort of gestalt just does not happen that often. We were also lucky to have detractors, powerful and entrenched ones, who provided not only the inspiration to stay the course, but a real-time insight into the way that “science” really works, as well as a lot of entertainment.

All told, it just does not get any better; Hollywood could not have written a better script.

Reference

Ellis J. 2014. Porcine circovirus: a historical perspective. Veterinary Pathology. 51:315-327.

May 2014