Camp Montoro, Jordi

Universitat Autònoma de Barcelona. Facultat de Veterinària

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EVALUATION OF THE IMMUNITY AGAINST THE PRRS VIRUS IN PIGLETS FROM VACUNATED SOWSFACULTY OF VETERINARY MEDICINE JORDI CAMP MONTORO FINAL DEGREE PROJECT   JUNE 2018INTRODUCTIONPorcine reproductive and respiratory syndrome (PPRS) has becomeone of the most important diseases of intensive pig productionworldwide. One of the points to emphasize is the humoral immunity,the PRRSV presents a genetic variability and an interaction with theimmune system that can have an important impact on the protectiongiven by the vaccines.OBJECTIVES The present study pretends to analyze the presence and duration ofmaternal antibodies against PRRSV in piglets during the period oflactation and transition, and study how the parity of each sow andthe number of vaccinations received can be influence. Secondly, theobjective will be to evaluate passive immunity in piglets that areviremic to PRRS.MATERIALS AND METHODS1 Unstable farm in PRRSVPorcilis® PRRS (MLV)1 per parity3 replicas / follow-ups2, 4, 7 and 9 weeks of ageBlood sampleSerum sampleSamples were stored in boxes of 96  at - 80 ºC360 serum samples of 148 piglets of 34 different sowsELISA for antibody detection against PRRS (IDEXX PRRS X3 Ab Test)PositivecontrolNegative controlFigure 1: Results obtained in one of the ELISA plates carried out in the study.RESULTS 1. Vaccination of sows on an unstable farm in PRRS allows the transmission of a good passive immunity to piglets. Therefore, most animals arepositive to ELISA antibody, but the protection is not enough to prevent PRRSV infection.2. The duration of passive immunity in the presence of the PRRS virus is between 4 to 7 weeks, lower than farms where the virus does not circulate.3. There was no relation between the number of vaccinations received by sow before farrowing and the duration of the immunity transmitted tothe piglets in that part. However, it has been proved that the sows of major parity confer a lower passive immunity to piglets, although they havereceived a greater number of vaccinations.CONCLUSIONS 305 positive simple to ELISA (84,72%) 265 positive simple to PRRSV (73,61%)Evaluation of the main resultsELISA+ - TotalPRRSV+ 210 55 265- 95 0 95Total 305 55 3600,000,501,001,502,002,503,002 - set. 4 - set. 7 - set. 9 - set.Ratio M/PTempsParitat 1 Paritat 3 Paritat 4 Paritat 5 Paritat 7 Paritat 9 Paritat 11Table 1: Distribution of the results of the variables ELISA and PRRSV considering the totality of the samples.Figure 2: Box-plot of the S/P ratio and the different weeks of age in the study considering the main results          (p-value < 0.00001).Evaluation of the samples of the Replica 1Figure 3: Evolution of immunity throughout lactationand transition weeks in replica 1.Figure 4: Evolution of immunity per parity throughoutlactation and transition weeks in replica 1. Statisticallysignificant differences were observed between parities1+4+5 and 7+9+11 (p-value < 0,0114).In PRRS endemic farms with a vaccination programin sows, most piglets are positive to ELISA andpresent a good passive immunity although theycan be infected by PRRSV. So viremic piglets willhave a role in the re-circulation and persistence ofthe virus in the farm. Infection pressure results in afaster decrease of the immunity causing a nothomogenous protection and variability in the S/Pvalues (Figure 2).About the evolution of the immunity, there is adecrease of the antibodies until week 7 when itincreases again (Figure 3). This is related to theinfection of piglets during the weeks 4 to 7 due tothe presence of viremic piglets in transition afterthe weaning at week 3. Therefore, the duration ofthe passive immunity is lower than in stable farmsto PRRS.Finally, a more number of vaccinations per sowdon’t lead to a better immunity. It is observed thatsows with more parities become anergic andtransmit a lower passive immunity than sows withless parities (Figure 4).DISCUSSION

Evaluation of the immunity against the prrs virus in piglets from vacunated sows

https://ddd.uab.cat/pub/tfg/2018/194908/TFG_jcampmontoro_poster.pdf

Evaluation of the immunity against the prrs virus in piglets from vacunated sows

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