Study of the antiviral effect of baculovirus in chickens: modulation of avian innate immunity

CHIMENO-ZOTH S.; CARBALLEDA, J.M.; GRAVISACO, M.J.; GÓMEZ, E.; LUCERO, S.; CARRILLO, E.; BERINSTEIN, A.

Edinburgo

Encuentro; XII Avian Immunology Research Group Meeting; 2012

Baculoviruses (BVs) are dsDNA viruses which infect insects. They have been used as selected bioinsecticides and for the expression of heterologous proteins in insect cells. Several reports showed that BVs have strong adjuvant properties on the mammalian immune system. Recent studies of our group demonstrated the ability of BV to stimulate the innate immunity in chickens. Infectious Bursal Disease Virus (IBDV), member of the Birnaviridae Family, is an endemic agent in most poultry producing areas worldwide, causing an acute, highly contagious, immunosuppressive disease in chickens. The purpose of the present work was to study the potential antiviral effect of BV against IBDV. White Leghorn SPF chickens of 28 days were intravenously inoculated with 108 pfu of Autographa californica nuclear polyhedrosis virus and 3 hours later, chickens received an oral dose (2x103 TCID50) of an intermediate strain of IBDV (determined in previous studies as a dose enough to produce signs of infection) with the corresponding controls of treatment. At 1 and 5dpi, animals were euthanized and their bursas, spleens and duodenum were excised to take samples for RNA extraction to be used in RT- Real Time PCR assays, and to isolate the lymphocytes, which were stained and analyzed by flow cytometry. Another piece of each bursa was conserved at -70 °C until viral isolation. Results showed that the administration of baculovirus 3 hs before the inoculation with IBDV produced important changes in the effect that IBDV causes in the bursa. While IBDV infection induces the infiltration of T lymphocytes in the bursa, the inoculation with BV before IBDV, diminishes this effect. Also, an inhibition of viral replication in this organ was observed. Finally, changes induced by IBDV in the expression of cytokine genes were attenuated in BV-IBDV treated chickens. The present work encourages future assays to propose BV as an antiviral agent for chickens.