IRES-based co-expression of influenza virus conserved genes can promote synergistic antiviral effects both in vitro and in vivo

Abstract

Vaccination is the most effective method for the prevention of influenza virus infection. Currently used influenza vaccines that target the highly polymorphic viral surface antigens can provide protection when well matched with circulating virus strains. Antigenic drift or cyclically occurring pandemics may hamper the efficacy of these vaccines, which are chosen prior to each flu season. Therefore, a universal vaccine, designed to induce broadly cross-protective immunity against the highly conserved internal antigens M1 and nucleoprotein could provide durable protection against various influenza virus subtypes, and it could also reduce the impact of pandemic influenza, which occurs less frequently. Here, we describe a new influenza vaccine candidate in which two highly conserved antigens, nucleoprotein (NP) and matrix (M1), are simultaneously expressed from a bicistronic vector termed pIRESM1/NP. Mice were immunized intradermally four times with the pIRESM1/NP construct. The protection efficacy of the gene-based vaccine was assessed by IFN-γ and Granzyme B ELISpot assays, follow-up observation of weight loss, and survival rates of the mice groups against lethal challenges with influenza A virus subtypes H1N1 and H5N1. The group that received pIRESM1/NP showed full protection against disease following lethal challenge with H1N1 and H5N1. This group also generated significantly higher host immune cellular responses than the other groups. These results demonstrate that a DNA vaccine strategy based on co-expression of the M1 and NP proteins could provide an effective way to control influenza virus infection.

Efficacy of recombinant NP-M1 and NP-M1-CRT DNA vaccines against Influenza A viruses in mice C57/BL6

“…Until now, more than six clinical trials as influenza DNA vaccines are being carried out and most of those vaccines are administered parenterally [35, 36]. Another universal influenza DNA vaccine is based on modified vaccinia virus Ankara (MVA), administration of this candidate vaccine (MVA-NP+M1) revealed good safety in humans and induced strong immune responses 6 months after immunization [37,38].…”

2A and 2A-like Sequences: Distribution in Different Virus Species and Applications in Biotechnology

“…Various approaches have been employed to co-express multiple proteins in cells, including the use of internal ribosomal entry site (IRES) elements [40,41], dual promoter systems [42,43], and transfection of multiple vectors [44]. Each of these is associated with several limitations, such as uneven or unreliable protein expression levels, silencing of some promoters [45,46], and increased toxicity to cells (with multiple transfections) [47].…”

Production and Application of Multicistronic Constructs for Various Human Disease Therapies

“…Simultaneous co-expression of several viral antigens can provide more effective immunization. For example, immunization of mice with a bicistronic vector expressing two highly conserved antigens of influenza virus, nucleoprotein (NP) and matrix (M1), separated by IRES has resulted in a full protection against the disease [99]. The same IRES-based strategy has been used to create a vaccine against Staphylococcus aureus -induced mastitis [100], the immunization with which has reduced the incidence of mastitis in cows.…”