Porcine reproductive and respiratory syndrome virus (PRRSV) causes huge economic losses to the swine industry and has not been controlled even with extensive vaccination programs. The virus is believed to be spread by fomites and by air. It is particularly difficult to control because of rapid mutations that generate variant strains. The industry is always looking for better and cost-effective methods to inactivate PRRSV on swine farms.
Far-UVC light (207 to 222 nm) represents a new era in ultraviolet (UV) application for virus control because it can kill human and animal pathogens in occupied spaces without negatively affecting skin or eyes; thus, it is a safer option for disinfection compared to traditional UVC light (254 nm).
In this study, the effect of far-UVC light (222 nm) was investigated against aerosolized PRRS virus and on PRRS virus-contaminated surfaces. A special environmental chamber was designed to aerosolize PRRS virus and measure the inactivation effects of different doses of far-UVC. Experiments were conducted using one, two, and three pairs of UVC lamps. For testing the effect of far-UVC on PRRS virus-contaminated surfaces, the virus was loaded onto discs of stainless steel, polypropylene plastic, polyvinyl chloride plastic (PVC), and aluminum. The PRRSV was loaded onto coupons (~1 cm2) of these fomites (at 30 μL of virus per coupon), air-dried for one hour, and then exposed to far-UVC at distances of 8 and 12 inches for 1, 2, 4, 6, 8, and 10 minutes.
The rates of inactivation of aerosolized PRRSV were 50% and 90% with two and three pairs of lamps, respectively, while a single pair did not cause any inactivation.
The rates of viral inactivation after a 10-minute exposure with three pairs of lamps on various surfaces were:
- Stainless steel: 99.72% at an 8-inch distance and 99.40% at a 12-inch distance
- Polypropylene plastic: 99.22% at an 8-inch distance and 98.34% at a 12-inch distance
- Polyvinyl chloride plastic (PVC): 97.25% at an 8-inch distance and 97.25% at a 12-inch distance
- Aluminum: 99.22% at an 8-inch distance and 99.24% at a 12-inch distance
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