Study shows pigs vaccinated with INGELVAC PRRS MLV had significantly higher post-challenge average daily weight gain compared to pigs vaccinated with Prevacent PRRS

Key Takeaways

 

• Pigs vaccinated with INGELVAC PRRS MLV demonstrated a significant improvement in average daily weight gain (ADWG) compared to the placebo group and pigs receiving Prevacent PRRS.¹

• Pigs vaccinated with INGELVAC PRRS MLV had a significant reduction in viremia compared to pigs receiving the placebo, while the reduction of viremia in pigs vaccinated with Prevacent PRRS was not significantly different compared to the placebo group.¹

• Both Ingelvac PRRS MLV and Prevacent PRRS significantly reduced lung lesions compared to the placebo group.¹

• While both vaccines demonstrated efficacy in the face of a heterologous PRRS challenge, this study provides additional evidence that PRRSV protection can’t be predicted by a vaccine’s lineage origin or its sequence similarities to field strains.^1-3

For more than 25 years, Boehringer Ingelheim has been helping the swine industry combat the costly effects of porcine reproductive and respiratory syndrome (PRRS). When INGELVAC PRRS MLV was introduced, it was the first of its kind, and it continues to be the leading modified-live PRRS vaccine, having demonstrated its ability to provide heterologous protection against numerous wild-type PRRSV strains that differ from their parent strain in nucleotide sequence and lineage in multiple controlled experimental and field research studies.^2-5 

To evaluate and compare the efficacy of INGELVAC PRRS MLV and Prevacent PRRS against a heterologous PRRSV 1-7-4 challenge, Boehringer Ingelheim conducted a randomized, blinded challenge study.¹

In the study, INGELVAC PRRS MLV and Prevacent PRRS demonstrated heterologous protection by significantly reducing lung lesions, and also significantly improving average daily weight gain (ADWG) compared to the challenge control group that received a placebo.¹ However, pigs vaccinated with INGELVAC PRRS MLV had significantly higher post-challenge ADWG compared to pigs vaccinated with Prevacent PRRS, further demonstrating the ability of INGELVAC PRRS MLV to provide leading protection against a relevant and contemporary lineage 1 PRRSV strain.¹ 

Key Findings

 

• During the post-vaccination/pre-challenge phase of the study: 

  • There were no significant differences in ADWG between vaccinates and pigs receiving the placebo; and

  • Pigs vaccinated with INGELVAC PRRS MLV showed no signs of negative performance impacts, demonstrating the vaccine’s ability to generate a robust, protective immune response and contribute to a safe, smooth start for growing pigs.

• During the challenge phase of the study:

  • Pigs vaccinated with INGELVAC PRRS MLV and Prevacent PRRS had significantly reduced lung lesions compared to the placebo group;

  • Pigs vaccinated with INGELVAC PRRS MLV demonstrated a significant improvement in ADWG compared to the placebo group and pigs receiving Prevacent PRRS; and

  • Pigs vaccinated with INGELVAC PRRS MLV had a significant reduction in viremia compared to pigs receiving the placebo, while the reduction of viremia in pigs vaccinated with Prevacent PRRS was not significantly different compared to pigs receiving the placebo.¹

Study Objective

 

To evaluate the efficacy of INGELVAC PRRS MLV and Prevacent PRRS in a 3-week-old-pig respiratory challenge model, using a heterologous PRRSV 1-7-4 field strain.  

Study Design

 

To begin, 108 PRRS-naïve, 3-week-old-pigs were randomized into three groups, and intramuscularly administered INGELVAC PRRS MLV or Prevacent PRRS according to their label directions or given a placebo. Pigs were housed in separate rooms by group during the post-vaccination/pre-challenge period. 

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The study included the following steps: 

• On Day 0 of the study, pigs were administered vaccines or a placebo and separated into rooms by group.

• On Day 27, pigs were moved to a location where they were commingled and challenged with a virulent 1-7-4 PRRSV strain administered intramuscularly and intranasally.

• Serum samples, weights and temperatures were collected periodically from Day 0 through Day 42.

  • Pigs were tested by serum polymerase chain reaction (PCR) at days 0, 7, 14, 21, 27, 29, 31, 33, 35 and 42 for PRRSV. Serum samples were tested by RT-PCR for the presence of viremia and by enzyme-linked immunosorbent assay (ELISA) for the presence of anti-PRRSV antibody. Data were analyzed using generalized and linear mixed models.

• On Day 42 (14 days post challenge), all pigs were necropsied and lungs were scored for the presence of macroscopic lesions. 

Study Results

 

• As seen in Figure 2, pigs vaccinated with INGELVAC PRRS MLV and Prevacent PRRS had significantly reduced lung lesions compared to pigs receiving the placebo.¹

• As seen in Figure 3, there was no difference in ADWG between vaccinated and placebo groups during the pre-challenge phase of the study. In the challenge phase of the study (Day 27 – Day 42), pigs vaccinated with INGELVAC PRRS MLV had significantly higher ADWG compared to the Prevacent PRRS vaccinated and placebo groups.¹

• Pigs vaccinated with INGELVAC PRRS MLV had a significant reduction in viremia compared to pigs receiving the placebo, while pigs vaccinated with Prevacent PRRS did not show a significant difference in the reduction of viremia compared to pigs receiving the placebo.¹

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Conclusions

 

During the post-vaccination/pre-challenge phase of this study, there were no significant differences in ADWG between either of the vaccinated groups and the placebo group.¹

In the challenge phase, pigs vaccinated with INGELVAC PRRS MLV and Prevacent PRRS had significantly reduced lung lesions compared to the pigs receiving the placebo. In addition, pigs vaccinated with INGELVAC PRRS MLV demonstrated significantly higher ADWG compared to the placebo group and pigs vaccinated with Prevacent PRRS.¹

For more than 25 years, producers and veterinarians have depended on Boehringer Ingelheim as a partner in swine health to help combat PRRS. This study further demonstrates why INGELVAC PRRS MLV continues to be the leading PRRS vaccine. 

 

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References

¹ Philips R, Haiwick G, Whiteman D, et al. Comparative efficacy of Ingelvac PRRS^® MLV against a heterologous PRRSV 1-7-4 challenge. 2022. Available at: https://www.prrs.com/expertise/publications/comparative-efficacy-ingelvac-prrs-mlv-against-heterologous-prrsv-1-7-4. Accessed June 6, 2022

² Patterson A, Victoria J, Jordan D, et al. Modified-live PRRS vaccination is efficacious following challenge with eight genetically diverse PRRSV isolates, in Proceedings. Allen D. Leman Swine Conf. 2013.

³ Patterson A, et al, Efficacy of Ingelvac PRRS modified live virus vaccine against heterologous PRRSV challenges.  J Vaccines Vaccin 2019;10:407.

⁴ Patterson A, Fergen B, Hermann J, et al. Efficacy of Ingelvac PRRS^® MLV against a heterologous PRRS 1-7-4 RFLP challenge, in Proceedings. Amer Assoc Swine Vet 2017.

⁵ Patterson A, Fergen B, Hermann J, et al. Efficacy of Ingelvac PRRS^® MLV against a heterologous PRRSV 1-3-4 RFLP challenge, in Proceedings. Allen D. Leman Swine Conf.   2017.

INGELVAC PRRS^® is a registered trademark of Boehringer Ingelheim Vetmedica GmbH, used under license. All other trademarks are property of their respective owner. ©2022 Boehringer Ingelheim Animal Health USA Inc., Duluth, GA. All Rights Reserved. US-POR-0130-2022