Location: Virus and Prion ResearchTitle: MontanideTM Gel01 ST adjuvant enhances PRRS modified live vaccine efficacy by regulating porcine humoral and cellular immune responses Author
Submitted to: World Journal of Vaccines
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/28/2012
Publication Date: 2/1/2013
Publication URL: http://handle.nal.usda.gov/10113/57060
Citation: Li, X., Galliher-Beckley, A., Nietfeld, J.C., Faaberg, K.S., Shi, J. 2013. MontanideTM Gel01 ST adjuvant enhances PRRS modified live vaccine efficacy by regulating porcine humoral and cellular immune responses. World Journal of Vaccines. 3(1):1-9. Interpretive Summary: Porcine reproductive and respiratory syndrome (PRRS) is the number one disease problem in pigs that is faced by U.S. pork producers, resulting in significant economic losses. Modified live vaccines against viruses are widely used to control many infectious diseases in a wide variety of hosts. Currently, commercially available modified live PRRS virus (PRRSV) vaccines afford the greatest degree of cross protection (compared with inactivated vaccines) against divergent strains of the PRRS virus. In this study an additive (known as an adjuvant) that is used to enhance the immune response to killed vaccines was tested in a modified live PRRSV vaccine. Addition of the adjuvant was found to enhance protection against the same virus strain in the vaccine but failed to enhance cross protection against a divergent strain of PRRSV. This information is of value to vaccine manufacturers attempting to improve cross-protective immunity afforded by vaccines against this evolving virus.
Technical Abstract: Porcine reproductive and respiratory syndrome (PRRS) is a devastating disease caused by the PRRS virus. The MontanideTM class of flexible polymeric adjuvants has recently been shown to enhance protective immunity against PRRSV infection in piglets when used in combination with PRRS modified live vaccines (MLV). In this study, we explored the efficacy and immunological mechanisms of protection of MontanideTM Gel 01 ST (Gel01) adjuvanted modified live PRRS vaccine in pigs challenged with two genetically distinct strains of PRRSV. Gel01-MLV reduced lymph node pathology scores in pigs challenged with VR2332 (parental strain of MLV vaccine) but not that in pigs challenged with MN184A (heterologous strain), when compared to that in pigs vaccinated with un-adjuvanted MLV. Pigs vaccinated with Gel01-MLV had higher levels of PRRS-specific antibodies, as measured by IDEXX ELISA and virus neutralizing antibodies, after vaccination and VR2332 challenge. In addition, pigs vaccinated with Gel01-MLV had decreased levels of IFN-gamma, IL-10, and T-regulatory lymphocytes in the blood as compared to that in pigs vaccinated with MLV alone. Interestingly, we found that addition of Gel01 did not change the profile of other T lymphocyte populations after PRRSV challenge. These results demonstrate that the MLV adjuvanted with Gel01 provides enhanced protection against homologous PRRSV infection, possibly by regulating the production of PRRSV-specific antibodies and cytokines involved in the development of T-regulatory cells. Thus, Gel 01 ST is a promising adjuvant that can be formulated with PRRSV MLV vaccines to reduce disease severity and tissue damage caused by PRRSV infection in pigs.