Abstract
The objective of this study was to compare the safety of all modified live virus vaccines commercially available in Europe against Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) under the same experimental conditions. For this purpose, one hundred and twenty three-week-old piglets, divided into five groups, were used. On day 0 of the experiment, nine pigs per group were removed and the remaining fifteen were vaccinated with the commercial vaccines Ingelvac PRRS MLV, Amervac PRRS, Pyrsvac-183 and Porcilis PRRS by the IM route or were mock vaccinated and used as controls. On day 3, the nine unvaccinated pigs were re-introduced into their respective groups and served as sentinel pigs. Clinical signs were recorded daily and lung lesions were determined on days 7, 14 and 21, when 5 vaccinated pigs per group were euthanized. Blood samples and swabs were taken every three days and different organs were collected at necropsy to determine the presence of PRRSV. None of the vaccines studied caused detectable clinical signs in vaccinated pigs although lung lesions were found. Altogether, these results indicate that all vaccines can be considered clinically safe. However, some differences were found in virological parameters. Thus, neither Pyrsvac-183 nor Porcilis PRRS could be detected in porcine alveolar macrophage (PAM) cultures or in lung sections used to determine PRRSV by immunohistochemistry, indicating that these viruses might have lost their ability to replicate in PAM. This inability to replicate in PAM might be related to the lower transmission rate and the delay in the onset of viremia observed in these groups
Highlights
Porcine Reproductive and Respiratory Syndrome (PRRS) is an economically significant disease of pigs that causes respiratory distress in piglets and reproductive failure in sows [1,2]
All experimental procedures were approved by the Animal Ethics Committee of the Universidad Complutense de Madrid and were conducted in accordance with the guidelines of the Good Experimental Practices (GEP) standard adopted by the European Union, which ensure the protection and welfare of the animals used in research
The major impact of PRRS virus (PRRSV) on pig production has stimulated the development of various types of vaccines, including inactivated virus and modified-live virus (MLV) vaccines for the control of the disease
Summary
Porcine Reproductive and Respiratory Syndrome (PRRS) is an economically significant disease of pigs that causes respiratory distress in piglets and reproductive failure in sows [1,2]. In general, PRRS is clinically similar in North America and Europe, the respective strains differ in virulence [4,5] and in antigenic [6,7] and genetic [8] properties. These differences have led to the classification of PRRSV isolates into two genotypes: type 1 that comprises viruses related to the European prototype Lelystad-virus and. Reversions to virulence have been suspected in the field based on the similarity between the vaccine strain and some strains that have caused clinical problems in areas where the vaccine has been used, regardless of whether the affected animals had been vaccinated or not [15,16]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
