Investigating the roles of cGAS and IFI16 in African swine fever virus innate sensing

Master Erasmus Mondus - Infectious Diseases and One Health (IDOH) ; Master ; African swine fever virus (ASFV) is a large cytoplasmic DNA virus with complex biology. The severity of the infection ranges from acute - with a lethality rate of almost 100% - to chronic infection without apparent clinical presentation. The pathogenicity and disease outcome of ASFV is strongly linked to the genomic alterations in the attenuated strains and to the differences in the innate immune response induced against the pathogen. Specifically, the production of inflammatory cytokines following infection has been reported to differ between ASFV isolates of different virulence. How the virus is sensed by the innate immune system remains however elusive. Previous work has shown that cGAS/STING pathway, contributes to ASFV sensing. Using the 3D4 cell lines, we aimed to use siRNA knockdown techniques to investigate the role of other sensors, including the IFI16 inflammasome, in ASFV detection. We showed that the 3D4 cell line expressed quantifiable levels of IFI16 but not of cGAS. Furthermore, the 3D4 cells, though previously reported to support ASFV replication, could not successfully be infected with the virulent (L60) or attenuated (NH/P68) ASFV strains. Using the primary alveolar macrophage cells, we reported that only the NH/P68 but not the L60 induced a potent interferon response and confirmed the involvement of STING as a key protein involved in ASFV sensing in macrophages. This work highlights the crucial need to develop an immortalized cell line that can be infected by ASFV to perform the mechanistic studies required to better understand the host-pathogen interplay of ASFV and swine.