Changes in chicken innate immunity induced by in vivo administration of baculovirus

SILVINA CHIMENO ZOTH; JUAN MANUEL CARBALLEDA; MARÍA J. GRAVISACO; EVANGELINA GÓMEZ; ELISA CARRILLO; A. BERINSTEIN

Budapest

Congreso; XI Avian Immunology Research Group Meeting; 2010

Baculoviruses (BVs) are dsDNA viruses which infect insects. They have been used as selected bioinsecticides and for the expression of recombinant proteins in insect cells. Recent studies showed that BVs have strong adjuvant effects on the mammalian immune system. The purpose of this work was to study the effect of in vivo administration of baculovirus in chickens.          SPF chickens of 20 days were intravenously inoculated with 108 pfu of Autographa californica nuclear polyhedrosis virus. Three hours later, chickens were bled, euthanized and their spleen, bursa, duodenum and cecal tonsils were excised in order to take samples for RNA extraction and Real Time PCR, and to isolate the lymphocytes, which were stained and analyzed by flow cytometry. Furthermore, splenocytes were cultured at 41oC and nitric oxide (NO) production was measured in the culture supernatant by the Griess reaction. gIFN production was also evaluated in the culture medium of purified splenocytes. RNA was extracted from spleen tissue and the expression of gIFN, aIFN, IL-8, LITAF, IL-15, IL-6 and TGFb was measured by real time RT-PCR. The results obtained showed that baculovirus inoculation up-regulates the expression of gIFN, IL-6 and LITAF in spleen cells when compared with samples from chickens inoculated with supernatant of mock-infected cells. This result was in agreement with those obtained by ELISA which showed a very strong increase of gIFN in splenocytes supernatants and in chicken plasma. Flow cytometry analysis revealed that BV inoculation induced a decrease in the percentage of T-lymphocytes, mainly of CD3+CD4+, accompanied by an increase in the frequency of NK cells in cecal tonsils. On the other hand, in spleen, an increment in the percentage of monocyte/macrophage population was detected, together with an increase in T lymphocytes CD3+CD4+. In bursa, a drop in the frequency of monocyte/macrophage population due to BV inoculation was observed. Finally, intraepithelial lymphocytes of the gut did not show differences between BV and control treated animals. Although, further studies in order to understand the mechanisms by which baculoviruses affect the avian immune response, are needed, results obtained in the present work demonstrate the ability of baculoviruses to stimulate the innate immunity in chickens, modifying the expression pattern of related genes and the profile of immunocompromised cells.