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A severe PRDC challenge and the effect of a trivalent PRDC vaccine for PCV2, Mhp and PRRS

Philips, E. Fano, Boehringer Ingelheim Vetmedica, Inc., MO, USA; E. Schmaling, R. Edler, Health Management Center (HMC), Field Research Services, BIVI, Ames, Iowa

INTRODUCTION

Porcine respiratory disease complex (PRDC) is a significant challenge for the global swine industry. PRDC includes both viral and bacterial respiratory pathogens, mainly Porcine Reproductive and Respiratory Syndrome Virus (PRRSV), Porcine Circovirus type 2 (PCV2), Mycoplasma hyopneumoniae (Mhp) and secondary bacterial agents. Vaccine derived immune protection against clinical disease associated with PRDC pathogens is one control intervention. 

The purpose of this controlled-experimental study was to evaluate pigs vaccinated with 3FLEX®(a trivalent PCV2, Mhp and PRRS vaccine) compared to a non-vaccinated group following a severe PRDC challenge.

MATERIALS AND METHODS

Group 1 was a non-vaccinated challenged control group of 20 pigs. Group 2 was a 3FLEX® vaccinated and challenged group of 20 pigs. Groups 1 and 2 were simultaneously inoculated with PCV2d (intranasal and intramuscular), Mhp strain 232 (intra tracheal) and PRRSV strain SDSU-73 (intranasal and intramuscular). The challenge incorporates a well referenced virulent heterologous PRRSV isolate, a contemporary virulent PCV2 field isolate, given simultaneously with Mhp,representing a severe PRDC challenge.

Table 1: Post-challenge clinical observations

Numbers shown in this table are representative of the total number of observations and events of the 20 animals per group. Analyzed using Pearson’s chi-square.

Table 2: Least square means for percent lung lesion by treatment

  • ab Means Differ <0.05 Wilcoxon rank sums test
  • * SD = standard deviation
  • ** SE = standard error

Table 3: Summary inferential statistics for PCV2 variables. Improvement compared to challenge controls​

 

RESULTS

Significant differences (P<0.05) in respiratory clinical signs, gross lung lesions and PCV2 parameters (Lymphoid depletion, IHC and Viremia) are shown in Tables 1, 2 and 3. A reduction in post-challenge PRRSV viremia (Figure 1), and increased average daily weight gain was demonstrated (Table 4) in vaccinates compared to non-vaccinates. Based on clinical, pathological and production results from this study a severe PRDC challenge was successfully accomplished.

As stated in the introduction, the purpose of this controlled-experimental study was to evaluate pigs vaccinated with 3FLEX® (a trivalent PCV2, Mhp and PRRS vaccine) compared to a non-vaccinated group following a severe PRDC challenge.

DISCUSSION AND CONCLUSION

The results of this trial demonstrate that 3FLEX® provides protection to pigs simultaneously challenged with PRRS, PCV2 and Mhp. In the face of severe PRDC challenge, use of a trivalent vaccine mixture is an option for mitigation of the biologic impact of PRDC.

Table 4: Summary descriptive statistics for growth performance from day 28 (challenge) to 56 (end of the study). Average Daily Gain, lbs.

  • * SD = standard deviation
  • ** SE = standard error
  • *** CV = coefficient of variation

Figure 1: Percentage positive and average CT for PRRS PCR results​

 

3FLEX is a registered trademark of Boehringer Ingelheim Vetmedica GmbH. ©2018 Boehringer Ingelheim Vetmedica, Inc. POR-0937-3FLX0418

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POR-0937-3FLX0418