Porcine circovirus type 2 (PCV2) causes multisystemic and reproductive disease in swine. Reported cases of PCVAD have increased in recent years. Porcine circovirus associated diseases are widespread in the U.S., Europe and reported from most swine-producing areas.
While humoral immunity, a type of adaptive immunity that involves the production of antibodies by B cells to fight against pathogens, is important for protection against PCV2, cell mediated immunity (CMI) may be more important for virus clearance and shedding reduction, says Jacqueline Springer, a student in the University of Illinois College of Veterinary Medicine.
Previous research has demonstrated that the Fostera Gold vaccine induced a higher cell-mediated immunity (CMI) response in growing pigs compared to an alternative vaccine, she said during her student oral presentation at the American Association of Swine Veterinarians annual meeting.
“CMI is the part of the immune response that utilizes cells like T helper cells and killer T cells,” Springer says. “These are much harder and more expensive to measure than antibodies that are part of the humoral immune response. This is why CMI is often not measured in normal production settings.”
Springer set out to evaluate CMI responses in mature breeding swine utilizing two different testing methods for the evaluation to see how the assays compared to each other.
“This study compared two PCV2 vaccines by evaluating the CMI response through both flow cytometry and ELISpot testing,” she says.
The study followed 40 sows (approximately 57 weeks old) that were randomly selected from a pool of 89 animals. All subjects had previously received FLEXCombo vaccination at about 27 weeks of age, approximately 210 days before our study began, Springer says.
The sows were evenly divided into two PCV2 vaccine treatment groups with 20 animals each. Vaccinations were administered on day 0 according to group assignment, with sample collections occurring on days 0 and 18.
Analysis revealed comparable performance between both vaccines in ELISpot and Flow Cytometry assessments, with no significant differences detected, she says.
“It’s important to note that the study farm experienced an outbreak of the porcine reproductive and respiratory syndrome (PRRS) 1-4-4 L1C variant, which likely impacted our results due to PRRS’s immunosuppressive effects,” Springer says. “The PCV2 vaccine responses observed may differ from those that would have occurred without this concurrent PRRS challenge.”
The fact that these were mature breeding animals with previous vaccination for PCV2, along with the potential for PCV2 circulation in the herd, may have also played a role in these unexpected results, she points out.
“This research brings to light the importance of understanding immunity against PCV2, particularly the distinctions between humoral immunity and cell-mediated immunity responses,” Springer says. “It also demonstrated the significant impact that PRRS virus may have on the pig’s immune system and its ability to respond to vaccination during an active PRRS virus infection.”
Springer was one of 15 students who competed in the oral presentation contest at the AASV annual meeting. Read more here.
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