Activation of the immune response against Infectious Bursal Disease Virus after intramuscular inoculation of an intermediate strain

Abstract

Infectious bursal disesase is a highly contagious, wide spread immunosuppressive chicken disease caused by the Infectious Bursal Disease Virus (IBDV). IBDV is a two segmented double-strand RNA virus, member of the Birnaviridae family. In order to study the interaction between IBDV and the immune system, chickens were exposed to an intermediate IBDV strain by intramuscular route, and using Real Time PCR the expression of a panel of avian cytokines and chemokines in duodenum, spleen and bursa of Fabricius was analyzed. Also, splenic nitrite (NO2) production and the frequencies of different mononuclear cell populations were evaluated by Griess reaction and flow cytometry, respectively. Intramuscular (i.m.) IBDV inoculation promoted an over expression of proinflammatory cytokines IL-6, IL-15 and gIFN in spleen, which correlated with an increase of gIFN plasma concentration measured by ELISA, together with an increment of NO2 concentration in splenocyte supernatants at 1dpi. Results obtained in the present work showed that IBDV of intermediate virulence, given i.m., induced similar effects to those previously described for highly virulent IBDV in early innate immune responses. Considering that the i.m. route is the route of choice for the delivery of new generation vaccines, and that the use of recombinant antigens also requires the addition of adjuvants for proper immune stimulation, results presented here could contribute to identify suitable cytokines to be used or to be stimulated when utilizing subunit vaccines, for the improvement of prevention tools for avian health.