BACULOVIRUS INFECTION TRIGGERS DIFFERENT CYTOSOLIC DNA SENSING PATHWAYS IN MAMMALIAN CELLS

AMALFI SABRINA; MOLINA GUIDO NICOLÁS; TABOGA OSCAR; ALFONSO VICTORIA

Congreso; XXX Congreso Brasileiro de Virologia XIV Encontro de Virologia do Mercosul; 2019

The baculovirus AcMNPV is an enveloped virus with a dsDNA genome and is a pathogen of insects. The budded virus (BV) is capable of transducing genes under the control of an adequate promoter in mammalian cells, although it cannot replicate its genome in this host. Among the applications of baculoviruses as a biotechnological tool in mammals, it is worth mentioning their use for vaccine development, gene delivery and as immunomodulators. BVs induce a strong innate immune response in mammals that is capable of generating an unspecific antiviral state, independent of TLR pathways. Our previous reports using a reporter BV showed that the cytoplasm is the main destination reached by their genome in different cell lines. Thus, this work aims to study the role of baculoviral cytoplasmic nucleic acids in the production of an antiviral state in non-immune mammalian cells. We studied the involvement of different cytosolic DNA sensors in murine and human cells infected with BV. We evaluated the production of cytokines by qPCR and antiviral activity by protection against stomatitis vesicular virus infection. In first place, we demonstrate that RNA Pol III does not participate in the establishment of the antiviral state. We then studied the cGAS-STING pathway by CRISPR-Cas9 gene editing in murine cells and by trans-complementation of cGAS or cGAS and STING in HEK293 and HEK293 T (human epithelial cells), respectively. The results showed that STING was required for the establishment of an antiviral state in mammalian cells. Moreover, at least two different signaling pathways had an impact on STING and contributed to the baculovirus induced antiviral state. The detection of the viral genome by cGAS sensing induced the strongest cellular response and it was necessary for the production of IFN β. Additionally, the cGAS-independent STING activation produced an antiviral state in human epithelial cells where the production of IFN λ1 was involved. In conclusion, the results of this work show that the genome of the baculovirus AcMNPV has a relevant role in the establishment of an antiviral state and in the production of IFN I and III through its impact on the nucleic acids sensing pathway cGAS-STING.