Vaccination is the most effective measure for reducing and preventing influenza and related complications. In this study, we analyzed the mutation trend and the antigen dominant site changes of the amino acid sequence of hemagglutinin subunit 1 (HA1) of human influenza A virus (IAV) in the northern hemisphere from 2012 to 2022. According to the HA1 sequences of A/Darwin/6/2021 (H3N2) and A/Wisconsin/588/2019 (H1N1) recommended by the World Health Organization in the 2022 influenza season in northern hemisphere, we employed the mosaic algorithm to design three Mosaic-HA1 antigens through stepwise substitution. Mosaic-HA1 was expressed and purified in 293F cells and then mixed with the alum adjuvant at a volume ratio of 1:1. The mixture was used to immunize BALB/c mice, and the immunogenicity was evaluated. Enzyme-linked immunosorbent assay showed that Mosaic-HA1 induced the production of IgG targeting two types of HA1, the specific IgG titers for binding to H3 protein and H1 protein reached 10⁵ and 10³ respectively. The challenge test showed that Mosaic-HA1 protected mice from H3N2 or H1N1. This study designs the vaccines by recombination of major antigenic sites in different subtypes of IAV, giving new insights into the development of multivalent subunit vaccines against influenza.
Animals ; Influenza A Virus, H1N1 Subtype/genetics* ; Influenza A Virus, H3N2 Subtype/genetics* ; Mice, Inbred BALB C ; Mice ; Influenza Vaccines/genetics* ; Hemagglutinin Glycoproteins, Influenza Virus/genetics* ; Humans ; Antibodies, Viral/blood* ; Antigens, Viral/genetics* ; Immunoglobulin G/immunology* ; Female ; Orthomyxoviridae Infections/prevention & control* ; HEK293 Cells

In order to understand the prevalence and evolution of porcine reproductive and respiratory syndrome virus (PRRSV) in China and to develop subunit vaccine against the epidemic lineage, the genetic evolution analysis of PRRSV strains isolated in China from 2001 to 2021 was performed. The representative strains of the dominant epidemic lineage were selected to optimize the membrane protein GP5 and M nucleotide sequences, which were used, with the interferon and the Fc region of immunoglobulin, to construct the eukaryotic expression plasmids pCDNA3.4-IFNα-GP5-Fc and pCDNA3.4-IFNα-M-Fc. Subsequently, the recombinant proteins IFNα-GP5-Fc and IFNα-M-Fc were expressed by HEK293T eukaryotic expression system. The two recombinant proteins were mixed with ISA206VG adjuvant to immunize weaned piglets. The humoral immunity level was evaluated by ELISA and neutralization test, and the cellular immunity level was detected by ELISPOT test. The results showed that the NADC30-like lineage was the main epidemic lineage in China in recent years, and the combination of IFNα-GP5-Fc and IFNα-M-Fc could induce high levels of antibody and cellular immunity in piglets. This study may facilitate the preparation of a safer and more effective new PRRSV subunit vaccine.
Humans ; Animals ; Swine ; Porcine respiratory and reproductive syndrome virus/genetics* ; Porcine Reproductive and Respiratory Syndrome/prevention & control* ; HEK293 Cells ; Viral Envelope Proteins/genetics* ; Antibodies, Viral ; Viral Vaccines/genetics* ; Recombinant Proteins ; Vaccines, Subunit