February 28, 2011
US researchers discover UV light inactivates PRRS virus
US researchers have tested ultraviolet (UV) light as a method to inactivate the PRRS virus, and found that it works at the Swine Disease Eradication Center, University of Minnesota College of Veterinary Medicine.
It is known that ultraviolet light neutralizes viruses, bacteria and parasites by disrupting the nucleic acid and preventing further replication. In this respect, UV light is considered quite advantageous over other virus inactivating procedures such as solvent detergent and pasteurization which have limited efficacy against, non-enveloped or heat stable viruses.
A study was conducted to assess the effect of UV (254) on the concentration and viability of Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) on surfaces and materials commonly encountered on swine farms. A standard quantity (5×10(6) TCID(50), total dose) of a PRRSV modified live vaccine virus was inoculated onto two matched sets of surfaces/materials including wood, plastic, latex, rubber, Styrofoam, metal, leather, cloth, concrete, cardboard, glass and paper. One set was exposed to UV (254) radiation (treatments) and the other to incandescent light (controls) for a 24 hour period. During this time, treatments and controls were swabbed at 10 minute intervals from 0-60 minute post-inoculation (PI) and again at 24 hour PI.
The quantity of PRRSV RNA on each item at each sampling time was calculated by RT-PCR and the presence of viable PRRSV in each sample was determined by swine bioassay.
A significant reduction (p<0.0001) in the quantity of PRRSV RNA was demonstrated at 24 hour PI independent of treatment. In addition, a significant reduction (p=0.012) in the number of UV (254)-treated surfaces which harboured viable virus was observed at 60 minute (0/12 positive) when compared to control surfaces (5/12 positive). In addition, all UV (254) treated samples collected between 10 and 50 minute PI were bioassay negative.
The researchers suggest that UV (254) is an effective means to inactivate PRRSV on commonly encountered farm surfaces and materials and inactivation can be accomplished following 10 minute of exposure.
