Stability of five strains of PRRSV in tap water at different temperatures

Porcine reproductive and respiratory syndrome (PRRS) is considered one of the most economically important diseases of swine, as outbreaks in the U.S. continue occurring despite current rigorous biosecurity measures. Limited information is available regarding the possibility of water contamination and the role of this milieu in dissemination of the PRRS virus. In this study, the survivability of the PRRSV in tap water at three temperatures (4°C, 21-23°C, and 37°C) was assessed. Tap water obtained from a laboratory faucet underwent different treatments involving autoclaving and dechlorination. Four strains of PRRSV-2 (L1A 1-7-4, L1C 1-4-4 SD, L9 1-4-2, L5 2-5-2) and one of PRRSV-1 (Lelystad), grown in the MARC-145 cell line with titers ranging from 4.0 to 5.5 log10 TCID50/0.1 mL, were added to the water samples followed by incubation at different temperatures. At various times, the samples were removed and titrated in cell cultures to determine the amount of viable virus. While there were no major differences between virus strains and water treatments, results showed a statistically significant (p < 0.01) prolonged survivability at lower temperatures: all strains remained viable for over 28 days at 4°C, 3-7 days at 21-23°C, and more than 24 hour sat 37°C. The time required for a 99% decrease in virus titer (T₉₉) further confirmed its longer survivability at lower temperatures, and the comparisons among these results indicate a potential risk of drinking tap water as a PRRSV carrier in farms, especially at lower temperatures.