Development of a swine specific 9-plex Luminex cytokine assay and assessment of immunity after porcine reproductive and respiratory syndrome virus (PRRSV) vaccination: Elevated serum IL-12 levels are not predictive of protect

Authors: LAWSON, STEVEN - South Dakota State University; Lunney, Joan; ZUCKERMANNC, FEDERICO - University Of Illinois; OSORIO, FERNANDO - University Of Nebraska; NELSON, ERIC - South Dakota State University; WELBON, CRAIG - South Dakota State University; CLEMENT, TRAVIS - South Dakota State University; FANG, YING - South Dakota State University; WONG, SUSAN - New York State Department Of Health; KULAS, KAREN - New York State Department Of Health; CHRISTOPHER-HENNINGS, JANE - South Dakota State University

Submitted to: Vaccine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/12/2010
Publication Date: 5/10/2010
Citation: Lawson, S., Lunney, J.K., Zuckermannc, F., Osorio, F., Nelson, E., Welbon, C., Clement, T., Fang, Y., Wong, S., Kulas, K., Christopher-Hennings, J. 2010. Development of a swine specific 9-plex Luminex cytokine assay and assessment of immunity after porcine reproductive and respiratory syndrome virus (PRRSV) vaccination: Elevated serum IL-12 levels are not predictive of protect. Vaccine. 28(32):5383-5391.

Interpretive Summary: Currently, few standardized assays are available for determining cytokine responses in swine. Some swine cytokine enzyme-linked immunosorbent assays (ELISAs) are commercially available, but each cytokine analysis is performed separately on separate plates, requiring more sample and cost compared with a ‘multiplexed’ assay whereby multiple cytokines are evaluated at one time within a single sample. This manuscript describes the development of a Luminex multiplex swine cytokine assay to measure 9 cytokines simultaneously in pig serum. The assay detects innate [interleukin-1beta (IL-1ß), IL-6, IL-8, interferon-alpha (IFNa), TNFa]; regulatory (IL-10), Th1 (IL-12, IFN') and Th2 (IL-4) cytokines. The assay was then tested on sera collected from a porcine reproductive and respiratory syndrome virus (PRRSV) vaccine/challenge study. These cytokines were measured to assess correlations between serum cytokine levels and vaccination strategies that provided for different levels of protective immunity against PRRS. Pigs were vaccinated with a modified live vaccine (MLV) and subsequently challenged with a non-identical PRRSV isolate. Protection (as defined by no serum viremia) was observed in the MLV vaccinated pigs after PRRSV challenge but not those vaccinated with killed vaccine with adjuvant (KV/ADJ) or non-vaccinates. Multiple serum cytokines were altered by the PRRSV vaccination and challenge; but only significantly elevated levels of IL-12 were observed in the KV/ADJ group. However, this significant increase in serum IL-12 correlated with lack of protection against PRRSV viremia indicating the unique role of this cytokine in pigs. Additional studies using this assay to measure the local cytokine tissue responses may help in defining a protective cytokine response in PRRS and in designing efficacious vaccines, not only for PRRSV, but also for other swine pathogens.

Technical Abstract: A Luminex multiplex swine cytokine assay was developed to measure 9 cytokines simultaneously in pig serum and tested in a porcine reproductive and respiratory syndrome virus (PRRSV) vaccine/challenge study. This assay detects innate (IL-1ß, IL-6, IL-8, IFNa, TNFa); regulatory (IL-10), Th1 (IL-12, IFN') and Th2 (IL-4) cytokines. These cytokines were measured to assess correlations between serum cytokine levels and vaccination strategies that provided for different levels of protective immunity against PRRS. Pigs were vaccinated with a modified live vaccine (MLV) and subsequently challenged with a non-identical PRRSV isolate. Protection (as defined by no viremia) was observed in the MLV vaccinated pigs after PRRSV challenge but not those vaccinated with killed vaccine with adjuvant (KV/ADJ) or non-vaccinates. Multiple serum cytokines were altered by the PRRSV vaccination and challenge; but only significantly elevated levels of IL-12 were observed in the KV/ADJ group. However, this significant increase in serum IL-12 correlated with lack of protection against PRRSV viremia. Additional studies using this assay to measure the local cytokine tissue responses may help in defining a protective cytokine response and can be used for the targeted design of efficacious vaccines, not only for PRRSV, but also for other swine pathogens.