Comparative survival of five porcine reproductive and respiratory syndrome virus strains on six fomites.

Abstract

Background and aim: Despite the availability of vaccines, porcine reproductive and respiratory syndrome virus (PRRSV) continues to cause disease outbreaks in pigs worldwide. One of the reasons for this problem is the frequent mutation of the virus, which creates new variants. This study was conducted to determine the survival of five PRRSV strains on four non-porous and two porous fomites at 22-25°C (room temperature).

Materials and methods: Five strains of PRRSV (1-7-4, 1-8-4, VR 2332, 1-4-4 MN, and 1-4-4 SD) were used in this study. Circular pieces of aluminum, boot material, polyvinyl chloride, stainless steel, cardboard, and concrete were used as fomites. A small volume of each virus strain was placed on the fomite, followed by incubation at room temperature. The virus surviving at different time points was eluted in an eluent solution. Serial 10-fold dilutions of the eluate were inoculated in MARC-145 cells for virus titration. Multivariate analysis of variance (MANOVA) was used for statistical analysis, and post hoc analysis was used for multiple pairwise comparisons.

Results: Three of the five strains were inactivated within 36 h on non-porous fomites; the remaining two survived for 72 h. On porous fomites, all five strains were inactivated within 12 h. MANOVA at p < 0.05 indicated that the inactivation of strains 1-7-4 and 1-4-4 SD was significant compared with the other strains. In addition, the number of virus titers was significantly reduced on stainless steel compared to other fomites.

Conclusion: Our findings illustrate how the interaction between the PRRSV strain and fomite material affect viral stability over time. The results also provide an understanding of fomites' role in PRRSV epidemiology as indirect transmitters of the virus.