Starting in 1991, Dr. Roof discussed the "mystery pig," the development of Ingelvac PRRS vaccine, and new vaccines and products that have emerged in the last 25 years.

He also shared lessons learned and how and why PRRS and PRRS vaccine development has been so difficult.

Key Lessons Learned about PPRS

For PRRS, there is no "Solution in a Bottle". Dr. Roof explained that the initial control approach that was adopted was similar to PRV or Parvo which was a "Solution in a Bottle", meaning a vaccine or antibiotic could solve the disease.

"Despite the fact that I work for a vaccine company and we have lots of vaccines, PRRS is really only managed at a herd or regional level," he said.

He emphasized to the group that a "paradigm change allowed new and different solutions to be considered. We moved away from PRRS as a pig disease to looking at a production disease or whole herd approach which allowed a broader and integrated assessment of the disease that included diagnostics, epidemiology, management and vaccines."

Not all PRRS virus are created equal. There is tremendous variation within PRRS virus and not every PRRS isolate is created equal, he noted. The research from the '90s with VR-2332 versus 174 isolates found today are dramatically different clinically as well as how they behave in a pig.

One PRRS isolate usually takes over. "We manage PRRS in a mixed population in the field, but the reality is, if you expose pigs to multiple isolates, there's usually one that takes over," said Dr. Roof. "If we use that information, we might be able to make better decisions relative to risk as well as vaccine placement."

Remembering Dr. Michael Murtaugh

The 2018 North American PRRS Symposium was dedicated to the memory of Dr. Michael Murtaugh, a long-time faculty member of the University of Minnesota's College of Veterinary Medicine. Dr. Murtaugh was one of the original PRRS researchers and was the first to report on the genetics of PRRSV. He was also the founder of the North American PRRS Symposium.

"Mike was a tremendous partner to everybody in the PRRS industry, as well as BI, and almost all the work I presented today he touched in some way. We'll all remember Mike for his passion for quality, his passion for science, his passion for PRRS, and as you mentioned, his incredible sense of humor," said Dr. Roof. "PRRS isn't easy, and with his sarcasm and humor, it sort of helped all of us move forward against a tough disease, so I think it's tremendous that this conference really focused and highlighted his legacy. It was a privilege of mine to dedicate my talk to Mike."