In her recent master’s thesis, Isadora Machado, a graduate research assistant at the Iowa State University College of Veterinary Medicine, determined the amount of antibiotics needed to fight secondary infections caused by PRRS outbreaks. She found that her outbreak of PRRSv on a pig farm was associated with increased antibiotic use during the growing season. This revealed the importance of preventing her PRRSV infection in order to reduce antibiotic use.
PRRS is a serious pig disease that has caused significant economic losses to the global pork industry for more than 30 years. Not only does the PRRS virus strain directly cause death and disease in pigs, but as Machado explains in his study, PRRS also has immunosuppressive effects. The series of his PRRS viruses reduce the effectiveness of the immune system, increasing the risk of pigs to co-infections caused by bacteria such as: streptococcus with switzerland Grassella parasuis. “This requires veterinarians to use antibiotics strategically to treat affected animals, increasing the cost of treatment during growth,” Dr. Machado notes in the paper.
Antibiotic quantification
Machado and her colleagues found Antibiotic use in nursery pigs (delivered via injection and water) on the studied pig farms showed a significant increase of 379% during the 15-week PRRS epidemic period. At the same time, injectable antibiotic use also increased by 274% in farmed pigs near market weight.
Dr. Machado said in his paper that the antibiotic most frequently injected during the nursery stage was ampicillin, accounting for 49% of total injections, followed by lincomycin (31%) and enrofloxacin (20%). It has said. In the termination phase, 72% of the injections were lincomycin, followed by enrofloxacin (28%).
Development of gene editing
Meanwhile, further developments are taking place in the field of PRRS. Two established livestock genetics companies are using gene editing to produce pigs resistant to his PRRS virus. These pigs have been genetically edited so that they lack a protein that, when present on the cell surface, allows PRRS virus entry.
Gene editing is an effective technique in which a single gene is responsible for a trait. In this case, knocking out the single gene for producing this surface protein appears to be able to completely prevent PRRS infection. Offspring born from these pigs have also been gene edited.
Obtaining approval
PIC hopes to get PRRS-resistant pigs approved in other pork-producing countries, including the United States, Canada, China, Japan, Mexico, Brazil, and Colombia. A regulatory decision regarding the future use of this pig in the country was recently announced.
The US-based livestock genetics company accelegen The company recently began breeding gene-edited pigs that are resistant to PRRS.
Antivirus
Another way to prevent the PRRS virus from entering cells is to attach small molecules to protein entry “gates” on the surface of pig cells. In 2023, scientists at the University of Connecticut will use artificial intelligence to screen approximately 4 million small molecules to find one that appears to have a 100% success rate in clinical testing, even at small doses. He announced that he had succeeded in finding it. Trials in pigs are underway.