Immune suppression from PRRS vaccine: Can it differ based on the type of PRRS vaccine?
Vaccination with PRRS MLV vaccine is like a field virus infection because the virus in the vaccine still has its natural ability to replicate in the host, shedding to in-contact pigs, and potentially suppress the host immune response by altering pro-inflammatory cytokine production, especially IL-10.
Is IL-10 relevant for the PRRSV immune response?
IL-10 functions as an immunosuppressive cytokine that can inhibit the host immune response.
It is well established that IL-10 strongly inhibits cytokine production and proliferation fo CD4+ cells, in particular, the T helper cells (Th1), resulting in an inhibition of cell-mediated immune response.
According to our previous published studies, we found that pigs vaccinated with different PRRS MLV vaccine, either PRRSV-1 or PRRSV-2, upregulates different level of IL-10 depending on the virus used for the PRRS vaccine manufacture, suggesting that immune suppression from PRRS MLV vaccine could be differed by different PRRSV MLV.
Could this IL-10 up-regulation after the use of PRRS MLV vaccines interfere the efficacy of other piglet´s vaccines?
Consequently, these findings of IL-10 up-regulation following PRRSV MLV vaccination and its suppressive property might be interfering with the other vaccines.
Previously published studies showed that PRRSV infection or vaccination appears to decrease the efficacy of Mycoplasma hyopneumoniae bacterin, pseudorabies virus vaccine, and classical swine fever vaccine.
It is in an agreement with our research that PRRS MLV vaccine followed by PCV vaccine, a week apart, has a suppressive effect on PCV vaccine.
However, a suppressive effect depends on PRRS MLV vaccines*. Some suppress, but some do not.
On the other hand, our preliminary study of concurrent vaccination of PRRSV MLV and PCV-2 vaccine showed no effects on the induction of immune response and protective efficacy in infected pigs with co-infection of PRRSV and PCV2.
These results are in agreement with another published study in which the concurrent vaccination of PRRSV vaccine and PCV-2 vaccine showed no interfering properties on the vaccine efficacy.
However, these findings are needed for further investigation as they were conducted using only one PRRS MLV vaccine.
Finally, PRRSV MLV vaccination followed by other vaccines, at least 10-14 days, is recommended due to the ability of PRRSV-induced suppressive cytokine and interfering host immune response.
Vaccination programs should be managed properly for better safety concerns, reliable efficacy, and protection.
If you want to learn more about PRRS virus and the immune dysregulation it causes, please visit our chapter “Immunology” on prrscontrol.com
Swine Viral Evolution and Vaccine Research Unit, Chulalongkorn University, Thailand.