An evaluation of ultraviolet light (UV ₂₅₄) as a means to inactivate porcine reproductive and respiratory syndrome virus on common farm surfaces and materials

A study was conducted to assess the effect of UV ₂₅₄ on the concentration and viability of PRRSV on surfaces and materials commonly encountered on swine farms. A standard quantity (5×10 ⁶TCID ₅₀, total dose) of a PRRSV modified live vaccine virus was inoculated onto 2 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 24h period. During this time, treatments and controls were swabbed at 10min intervals from 0 to 60min post-inoculation (PI) and again at 24h 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 24h PI independent of treatment. In addition, a significant reduction (p=0.012) in the number of UV ₂₅₄-treated surfaces which harbored viable virus was observed at 60min (0/12 positive) when compared to control surfaces (5/12 positive). In addition, all UV ₂₅₄ treated samples collected between 10 and 50min PI were bioassay negative. These results suggest that UV ₂₅₄ is an effective means to inactivate PRRSV on commonly encountered farm surfaces and materials and inactivation can be accomplished following 10min of exposure.