Experimental quantification of the transmission of Porcine reproductive and respiratory syndrome virus.
We conducted an experiment to determine the ability of vaccine against Porcine reproductive and respiratory syndrome virus (PRRSV) to reduce the transmission of PRRSV among pigs. At the end of the experiment, transmission rates did not differ significantly (P = 0.61) between the vaccinated and nonvaccinated pigs, the mean R-values being 0.598 (95% confidence interval [CI] 0.136 to 3.218) and 0.264 (95% CI 0.008 to 2.266), respectively. The unusually low rate of PRRSV transmission in both groups may not have provided a sufficient challenge to detect a vaccine effect. Several factors could affect the rate of PRRSV transmission: isolate virulence, inoculation dose, inoculation route, number of passages of the challenge virus in cell culture, and population size. Of these, isolate virulence appears to be the most important factor associated with the low transmissibility observed in this study. More studies comparing rates of transmission between PRRSV isolates with diverse levels of virulence are needed to better understand this association.
Mondaca-Fernández
Enrique
E
Swine Disease Eradication Center, College of Veterinary Medicine, University of Minnesota, St. Paul 55108, USA. mond0027@umn.edu
Meyns
Tom
T
Muñoz-Zanzi
Claudia
C
Trincado
Carlos
C
Morrison
Robert B
RB
D000818:Animals; D004306:Dose-Response Relationship, Immunologic; D011156:Population Density; D019318:Porcine Reproductive and Respiratory Syndrome / Q000517:prevention & control / Q000635:transmission / Q000821:virology; D019316:Porcine respiratory and reproductive syndrome virus / Q000472:pathogenicity*; D011897:Random Allocation; D013045:Species Specificity; D013552:Swine; D013997:Time Factors; D014765:Viral Vaccines / Q000008:administration & dosage / Q000276:immunology*; D014774:Virulence
D014765:Viral Vaccines