Inactivated Influenza A H1N1 [A/New Cal/20/99]

Here, researchers conjugated the recombinant receptor binding domain (RBD) of the SARS-CoV-2 spike protein to inactivated influenza A virus (Flu) to develop a SARS-CoV-2 virus-like particle (VLP) vaccine with dual protection. This dual vaccine (Flu-RBD) not only induced protective immunity against SARS-CoV-2, but also functioned as an influenza vaccine. The Flu core improved the retention and distribution of the Flu-RBD vaccine in draining lymph nodes and enhanced immunogenicity. In a hamster model of live SARS-CoV-2 infection, two doses of Flu-RBD effectively protected the animals from viral infection. In addition, the Flu-RBD VLPs showed strong neutralizing activity against both SARS-CoV-2 Delta pseudovirus and wild-type influenza A H1N1 inactivated virus in mice. Overall, the Flu-RBD VLP vaccine is a promising candidate vaccine against COVID-19, influenza A, and co-infections.

In this study, the researchers investigated the protective effect of the Flu-RBD vaccine against red fluorescent wild-type influenza A H1N1 inactivated virus (Wild-type influenza A H1N1 (VNV-019) inactivated virus was purchased from Creative Biogene). Compared with the PBS control, Flu-RBD vaccination effectively accelerated the clearance of H1N1 inactivated virus in mice (Figure 1), indicating that the immunogenicity of the influenza vaccine was retained. In addition, they compared the neutralizing activity of Flu-RBD with the clinical standard vaccine LNP@mRNA plus FluZ and found that the protective effect of the Flu-RBD vaccine against H1N1 inactivated virus was similar to that of the LNP@mRNA plus FluZ group, indicating that the Flu-RBD vaccine has the potential to prevent influenza infection (Figure 1).

Figure 1. A comparison of Flu-RBD vaccine and mRNA vaccine plus influenza vaccine against wild-type influenza A H1N1 inactivated virus in mice. (Wang Z, et al., 2023)