Article from Farm Journal’s Pork, written by Jennifer Shike, highlights the science of PRRS 1-4-4.
This is the worst strain of PRRS virus ever.
Vaccines don’t work anymore.
Biosecurity protocols are ineffective.
“Those were consistent remarks from people in the field,” said Scott Dee, DVM, director of research for Pipestone Research, during a seminar at the Leman Swine Conference. “There were some weird twists going on with this strain of PRRS virus. We were having summer infections in regions of very low density. And really, what concerned us was people were giving up. There was a defeatist attitude permeating the industry.”
The swine industry is battling one of the toughest strains ever of porcine reproductive and respiratory syndrome (PRRS) virus – PRRS 1-4-4 Lineage 1C. Tired of not having answers to difficult questions, scientists at Pipestone Research and Boehringer Ingelheim Animal Health USA Inc., decided to look for answers. 
Following the leadership of Joel Nerem, Pipestone Research team members Scott Dee, Roy Edler and Dan Hanson put the wheels in motion, joined forces with Amanda Sponheim, Reid Philips and Justin Rustvold from Boehringer Ingelheim Animal Health USA Inc., and recently completed three studies targeting the field concerns.
Is PRRS 1-4-4 virus worse than PRRS 174 virus? 
During this first pathogenicity study, naïve pigs were challenged with either PRRS 1-4-4 virus or PRRS 1-7-4 virus. Outcomes included average daily gain (ADG), percent mortality, viral load, clinical scores, pyrexia and number of treatment events. Across all metrics, PRRS 1-7-4 virus was more pathogenic than PRRS 1-4-4 virus, Dee explained. 
Do vaccines still work on PRRS 1-4-4 virus? 
In the second study, pigs were vaccinated either with Ingelvac PRRS MLV (BI) or Prevacent PRRS (Elanco) and compared to a non-vaccinated control group. Vaccination was applied according to label instructions and challenge occurred 28-day post-vaccination. Dee shared both vaccines were effective against PRRS 1-4-4 virus and performance in vaccinated groups was significantly better than non-vaccinates. 
Can biosecurity protocols prevent PRRS 1-4-4 virus introduction? 
During the third study, six biosecurity protocols were tested on pigs challenged with PRRS 1-4-4 virus. The study evaluated transmission of 1-4-4 through feed using natural feeding behavior, transmission via contaminated personal and fomites (boots, coveralls and hands), the ability of the virus to be detected in aerosols from infected pigs, survival in slurry (14 vs 21 days) and the transport (feed truck) as a vehicle for viral movement between sites. In addition, intervention strategies, including two disinfectants (Ag Forte Pro or Synergize), two feed mitigants (Guardian or Sal CURB), air filtration (Camfill Farr MERV 14) and a shower protocol with a boots/coverall change, were tested to determine if the respective risks could be managed, he said.
Both Ag Forte Pro and Synergize disinfectants neutralized PRRS 1-4-4 virus after 60 minutes of contact. When PRRS 1-4-4 virus was transmitted through feed via natural feeding behavior, both feed mitigants (Guardian or Sal CURB) prevented infection. During transport, Dee said PRRS 1-4-4 virus survived in the feed transport model and infected pigs. The virus also survived in slurry for 14 days, but not 21 days. 
Following 30 minutes of contact with infected pigs, PRRS 1-4-4 virus was detected on hands, boots and coveralls of personnel. In the absence of a shower and clothes/footwear change, virus was transmitted to contact controls. After a shower and clothes/footwear change, virus was not transmitted to contact controls, Dee explained.
Read the full article HERE
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