by Boehringer Ingelheim Animal Health USA Inc./October 28, 2021
While a new strain of porcine reproductive and respiratory syndrome (PRRS) virus is proving to be especially challenging this year, recent research found that, under the conditions of the study, an existing strain is more pathogenic, leading to decreased performance across multiple categories, such as average daily gain (ADG) and mortality.1
The pathogenicity study, which was conducted by Pipestone Research and Boehringer Ingelheim, compared PRRS-naïve pigs challenged with PRRSV 1-7-4, which was identified in 2014, to pigs challenged with PRRSV 1-4-4 lineage 1C, the new strain causing concern across the industry this year. Researchers measured ADG, mortality rate, viremia, number of treatments and more, and found that across all categories, pigs challenged with PRRSV 1-7-4 had poorer outcomes than those challenged with PRRSV 1-4-4 lineage 1C, leading to the conclusion that PRRSV 1-7-4 is more pathogenic.1
By no means does the research suggest that PRRSV 1-4-4 lineage 1C is not a concern, but it serves as a reminder that with the right tools and protocols, producers can manage and mitigate the consequences of this new virus strain just like they’ve done for more than five years with PRRSV 1-7-4. This was demonstrated in the study, which found that pigs vaccinated with Ingelvac PRRS® MLV and challenged with PRRSV 1-4-4 lineage 1C had significantly better performance than non-vaccinated pigs.1
As new PRRSV strains have emerged over the years, testing the ability of INGELVAC PRRS MLV to protect against them has been and remains a top priority for Boehringer Ingelheim. Since 1994, the vaccine has proven its effectiveness against emerging strains in more than 20 cross-protection studies.2
Putting vaccines to the test against PRRSV 1-7-4
Earlier this year, Boehringer Ingelheim launched FLEX CircoPRRS®, a new vaccine that combines the efficacy and safety of INGELVAC PRRS MLV for PRRS with Ingelvac CircoFLEX® for PCV2. To test the vaccine’s ability to protect against PRRSV 1-7-4, researchers conducted a randomized, blinded vaccination-challenge study.
Three groups of 3-week-old, PRRS-naïve pigs were separated and either vaccinated with FLEX CIRCOPRRS or INGELVAC PRRS MLV, or given a placebo. On day 28 of the study (four weeks post vaccination), all three groups were commingled and challenged with PRRSV 1-7-4, a lineage 1 field isolate.
Researchers measured ADG and viremia throughout the post-challenge period (days 28–42) and gross lung lesion scores upon necropsy on day 42.
Results
In the post-vaccination, pre-challenge period, pigs vaccinated with INGLEVAC PRRS MLV and FLEX CIRCOPRRS showed no signs of negative performance impacts. There was no significant difference in pre-challenge ADG between the vaccinated and placebo groups, demonstrating the vaccines help provide pigs with a safe, smooth start.3
In the post-challenge period, pigs from both vaccinated groups had significantly better ADG (Table 1) and significantly reduced viremia compared to non-vaccinated pigs.3
Gross lung lesion scores were also significantly reduced among vaccinated pigs compared to non-vaccinated, with no significant difference between the two vaccine groups (Table 2).3
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This research demonstrates that whether using INGELVAC PRRS MLV alone or in a combination vaccine like FLEX CIRCOPRRS, producers can feel confident that the vaccine protects their pigs against new and established PRRSV field strains. To learn more, contact your Boehringer Ingelheim representative.
References
1 Dee S. PRRSV 144: A rapid response to a national crisis. Pipestone Research. Available at: https://www.pipestone.com/prrsv-144-a-rapid-response-to-a-national-crisis/. Accessed June 6, 2022.
2 Patterson A, Victoria J, Jordan D, et al. Modified-live PRRSV vaccination is efficacious following challenge with eight genetically diverse PRRSV isolates, in Proceedings. Allen D. Leman Swine Conf. 2013.
3 Boehringer Ingelheim internal data, Study No. 2021-1306.
INGELVAC PRRS®, FLEX CIRCOPRRS® and INGELVAC CIRCOFLEX® are registered trademarks of Boehringer Ingelheim Vetmedica GmbH, used under license. ©2022 Boehringer Ingelheim Animal Health USA Inc., Duluth, GA. All Rights Reserved. US-POR-0132-2022