Since emergence,the influenza virus has triggered numerous global pandemics and claimed more than ten million lives.This virus poses not only a severe threat to human life and health,but significant challenges to global economy and public health.The research on highly pathogenic influenza virus strains(such as H5 and H7)necessitates the use of biosafety level 3 laboratories,which significantly escalates the experimental risks and costs.The pseudovirus technology,as a relatively safe and effective research technique,has been applied in the studies of various high-risk viruses.Thanks to constant research and refinement,the pseudovirus technology for the influenza virus currently boasts such advantages as user-friendliness and good safety,and has been extensively used antibody neutralization and screening of antiviral drugs.This article reviews the research progress in the pseudovirus technology for the influenza virus.

Objective:To establish an antibody expression system to reduce the antibody-dependent enhancement (ADE) effect of target antibody.Methods:Site-directed mutagenesis was used to mutate the 234 and 235 sites of the Fc region of the mammalian cell antibody expression vector-L234A and L235A to establish the antibody expression vector pFRT-IgG1κ-FcM. An antibody Wt-WNV with significant ADE effect obtained in previous work was selected and expressed by the pFRT-IgG1κ-FcM system to obtain mutant antibody FcM-WNV. The binding ability of FcM-WNV to target antigen West Nile virus envelope protein-DⅢ (WNV E-DⅢ) was detected by ELISA, and the its binding ability to human high-affinity IgG Fc receptor hFcγRⅠ (hCD64 ) was analyzed by flow cytometry. The neutralizing activity of FcM-WNV in vitro was detected by pseudovirus infection of host cells (BHK21 and K562). Results:The expression levels of FcM-WNV and Wt-WNV were comparable, and FcM-WNV could recognize and bind to WNVE-DIII in a concentration-dependent manner. Compared with Wt-WNV, the binding ability of FcM-WNV to hCD64 was significantly weakened, showing a significant decrease in fluorescence intensity. Consistent with the previous experimental results, Wt-WNV at a concentration of 5 μg/ml significantly enhanced the infection of K562 by WNV pseudovirus, while FcM-WNV at a concentration of 5 μg/ml could effectively block pseudovirus infection in both K562 and BHK21 cells.Conclusions:The established antibody expression system can effectively reduce the ADE effect of the target antibody.

Objective:To establish an in vivo infection model of West Nile virus (WNV) pseudovirus and evaluate the neutralizing activity of antibody WNV-XH1.Methods:A stable cell line that can package the WNV pseudovirus was established in the early stage to prepare the pseudovirus supernatant. The supernatant was concentrated and infected BHK21 cells to detect the titer of the pseudovirus. After intraperitoneal injection of the pseudovirus into C57BL/J mice, bioluminescence imaging was performed to observe the infection status of the pseudovirus in the mice. After simultaneous infection, blood was collected and ELISA was used to detect NS1 levels in mouse serum. The in vivo functional activity of antibody WNV-XH1 was evaluated using the established mouse infection model.Results:Fluorescence was detected in C57BL/J mice infected with WNV pseudovirus, and the NS1 levels in the peripheral blood serum of mice infected with pseudovirus were significantly higher than those of non infected mice (1.453±0.09vs0.305±0.018). After intravenous administration of WNV-XH1 antibody before the attack, the fluorescence signal in the mice decreased and the serum NS1 level decreased (0.384±0.015).Conclusions:A successful in vivo infection model of WNV pseudovirus was established, and it was confirmed that the antibody WNV-XH1 had a protective effect against WNV pseudovirus infection in vivo.