Porcine reproductive and respiratory syndrome virus (PRRSV) and porcine circovirus 2 (PCV2) have found a new sticky protector: the bacterial biofilm, and thus penetrate into farms.
CRIPA members and researchers Mario Jacques (Université de Montréal) and Daniel Grenier (Université Laval) are experts in the sticky and gelatinous secretions produced by most bacterial species, including the pig nemeses Actinobacillus pleuropneumoniae, Escherichia coli and Streptococcus suis that cause serious infections. These bacteria use polysaccharides (sugar), protein and DNA to build a sticky substance that both protects them and glues them to an animal, like a pig, or to a surface.
Bacteria cover themselves in this glue to firmly stick themselves to a surface and reproduce. The end result is the development of an organized structure called a biofilm that acts like a coat of armour to shield bacteria from antibiotics and disinfectants. Recent studies suggest that viruses also take shelter within bacterial biofilms.
In collaboration with Carl A. Gagnon, a virologist in the Faculty of Veterinary medicine (UMontréal), and the technical assistance from research assistants Chantale Provost and Josée Labrie, researchers Jacques/Grenier demonstrated that PRRSV and PCV2 can take shelter within biofilms produced by several disease-causing bacteria allowing these viruses to survive several days. Amazingly, PCV2 even maintained its ability to cause infections.
The fight against biofilms
Luckily, trials with disinfectants commonly used on farms eliminated 90-100% of the bacteria as well as most of the viruses lurking within biofilms, even if the sticky substrate remained intact. These results shed light on a strategy used by viruses to persist on farms. Ongoing research efforts are focused on developing ways to prevent biofilm formation or to strip bacteria of their sticky armour.
Source : Jacques M, Grenier D, Labrie J, et al. Persistence of porcine reproductive and respiratory syndrome virus and porcine circovirus type 2 in bacterial biofilms. J Swine Health Prod. 2015;23(3):132–136.