Protection against mouse and avian influenza A strains via vaccination with a combination of conserved proteins NP, M1 and NS1.

Background: Experimental data accumulated over more than a decade indicate that cross-strain protection against influenza may be achieved by immunization with conserved influenza proteins. At the same time, the efficacy of immunization schemes designed along these lines and involving internal influenza proteins, mostly NP and M1, has not been sufficient.

Objective: To test the immunogenicity and protective efficacy of DNA vaccination with a combination of NP, M1 and NS1 genes of influenza virus.

Immunization with influenza A NP-expressing vaccinia virus recombinant protects mice against experimental infection with human and avian influenza viruses.

Two-fold immunization of Balb/c mice with a vaccinia virus recombinant expressing the NP protein of influenza A/PR8/34 (H1N1) virus under the control of a strong synthetic promoter induced specific antibodies and protected animals against low-dose challenge by mouse-adapted heterosubtypic variants of human A/Aichi2/68 (H3N2) and avian A/Mallard/Pennsylvania/10218/84 (H5N2) influenza virus strains. The surviving immunized animals had lower anti-hemagglutinin antibody titers compared to non-immunized mice. There was no difference in viral titers in lungs of immunized and non-immunized animals that succumbed to the infection.