Applying Baculovirus Surface Display Technology for Influenza Cytokine Profiling, Serological Detection and Antiviral Screening.

Influenza causes approximately one billion infections and hundreds of thousands of deaths each year. Occasionally, highly pathogenic new virus strains emerge. Research on emerging influenza viruses or multiple viral strains is often limited by the need for high biosafety level (BSL) laboratories. To overcome this limitation, we attempt to establish a BSL-1-compatible influenza research platform using baculovirus surface display technology. We constructed influenza virus pseudotypes HA-Bac and NA-Bac by displaying hemagglutinin (HA) and neuraminidase (NA) proteins from influenza viruses on the surface of baculoviruses. Different HA-Bac and NA-Bac induced a unique inflammatory cytokine profile after transduction into respiratory epithelial and macrophage cell lines. Using insect cells infected with these HA-Bac and NA-Bac as antigens, we established cell-based and lysate-based ELISA to detect HA and NA antibodies. The lysate-based ELISA showed excellent performance in detecting IgG antibodies in patients' serum samples. Finally, hemagglutination induced by HA-Bac-infected insect cells and neuraminidase activity generated by NA-Bac-infected cells were both inhibited by the corresponding antiviral drugs in functional inhibition assays. In summary, this study established a safe influenza research system capable of performing cytokine profiling, serological detection and antiviral drug screening under BSL-1 conditions. This system holds promise for application to other emerging respiratory viruses and support of public health preparedness.