Vet. Res. 38 (2007) 81-93
DOI: 10.1051/vetres:2006044

Effect of temperature and relative humidity on the stability of infectious porcine reproductive and respiratory syndrome virus in aerosols

Joseph Hermann^a, Steve Hoff^b, Claudia Muñoz-Zanzi^c, Kyoung-Jin Yoon^a, Michael Roof^d, Anna Burkhardt^a and Jeffrey Zimmerman<sup>a

a</sup>  Department of Veterinary Diagnostic and Production Animal Medicine, College of Veterinary Medicine, Iowa State University, Ames, Iowa 50011-1250, USA
^b  Department of Agriculture and Biosystems Engineering, College of Agriculture, Iowa State University, Ames, Iowa 50011-1250, USA
^c  Division of Epidemiology and Community Health, School of Public Health, University of Minnesota, Minneapolis, MN 55454, USA
^d  Boehringer Ingelheim Vetmedica, Inc., 2501 North Loop Dr., Suite 1000, Ames, Iowa 50010, USA

(Received 7 July 2006; accepted 13 September 2006; published online 8 December 2006)

Abstract - The objective of this experiment was to describe the stability of airborne infectious porcine reproductive and respiratory syndrome virus (PRRSV) as a function of temperature and relative humidity. A cloud of infectious PRRSV was aerosolized using 24-jet Collison nebulizer into a dynamic aerosol toroid (DAT) maintained at a specific temperature and relative humidity. The PRRSV cloud within the DAT was sampled repeatedly over time using SKC BioSampler impingers and the total viral RNA (RT-PCR) and concentration of infectious PRRSV (TCID₅₀) in the air samples was determined. As measured by quantitative RT-PCR, PRRSV RNA was stable under the conditions evaluated in this study. Thus, a comparison of viral RNA and Rhodamine B dye, a physical tracer, found no significant difference in the slopes of the lines. Titers of infectious virus were plotted by time and the half-life (T1/2) of infectious PRRSV was calculated using linear regression analysis. An analysis of the results showed that aerosolized PRRSV was more stable at lower temperatures and/or lower relative humidity, but temperature had a greater effect on the T1/2 of PRRSV than relative humidity. Based on these results, an equation was derived to predict the T1/2 of infectious airborne PRRSV for any combination of environmental temperature and relative humidity.

Key words: aerosol / virus stability / PRRSV / relative humidity / temperature

Corresponding author: jjzimm@iastate.edu

© INRA, EDP Sciences 2007