Immunogenicity and Protection Against Influenza H7N3 in Mice by Modified Vaccinia Virus Ankara Vectors Expressing Influenza Virus Hemagglutinin or Neuraminidase

Abstract

Influenza subtypes such as H7 have pandemic potential since they are able to infect humans with severe consequences, as evidenced by the ongoing H7N9 infections in China that began in 2013. The diversity of H7 viruses calls for a broadly cross-protective vaccine for protection. We describe the construction of recombinant modified vaccinia virus Ankara (MVA) vectors expressing the hemagglutinin (HA) or neuraminidase (NA) from three H7 viruses representing both Eurasian and North American H7 lineages – A/mallard/Netherlands/12/2000 (H7N3), A/Canada/rv444/2004 (H7N3), and A/Shanghai/02/2013 (H7N9). These vectors were evaluated for immunogenicity and protective efficacy against H7N3 virus in a murine model of intranasal challenge. High levels of H7-, N3-, and N9-specific antibodies, including neutralizing antibodies, were induced by the MVA-HA and MVA-NA vectors. Mice vaccinated with MVA vectors expressing any of the H7 antigens were protected, suggesting cross-protection among H7 viruses. In addition, MVA vectors expressing N3 but not N9 elicited protection against H7N3 virus challenge. Similar outcomes were obtained when immune sera from MVA vector-immunized mice were passively transferred to naïve mice prior to challenge with the H7N3 virus. The results support the further development of an MVA vector platform as a candidate vaccine for influenza strains with pandemic potential.

Extending the Stalk Enhances Immunogenicity of the Influenza Virus Neuraminidase

“…Unlike other pursued approaches designed to enhance anti-NA immunity that are based on isolated or recombinant NA proteins (11)(12)(13)37), DNA plasmids (10), virus-like and replicon particles (23,25), or virus-vectored vaccines (38), the NA stalk extension described here could be implemented in existing manufacturing processes for seasonal influenza virus vaccines, as the mutated NAs can be expressed on virus particles that efficiently replicate in eggs. Moreover, we provide evidence that the subdominance of the NA results in part from the height of the protein relative to the HA.…”

“…Consequently, supplementing seasonal vaccines with isolated NA proteins can enhance anti-NA responses in mice (36). More recently, NA vaccine candidates based on recombinant tetrameric NA proteins (11)(12)(13)37), DNA plasmids (10), virus-like or replicon particles (23,25), and modified vaccinia virus Ankara vectors (38) have been shown to induce heterologous anti-NA immunity in mice. In humans, purified N2 protein has been shown to induce heterologous antibody responses (28).…”

Broadly Protective Strategies Against Influenza Viruses: Universal Vaccines and Therapeutics

“…Recently, a recombinant modified vaccinia virus Ankara (MVA) vector was used to express either HA or NA from three different H7 viruses. Following vaccination with a MVA vector expressing N3 NA, mice were protected against challenge with H7N3 (Meseda et al, 2018). Likewise, a passive transfer of sera from MVA-N3 vaccinated mice into naive mice demonstrated protection against H7N3 infection (Meseda et al, 2018) In contrast, mice that received sera from the MVA-N7 vaccine were not protected against challenge with H7N3 despite the vaccine containing an NA from the same subtype as N3, suggesting that further optimization of this vaccine approach is required to elicit broader NA-based protection (Meseda et al, 2018).…”

Stability of the HSV-2 US-6 Gene in the del II, del III, CP77, and I8R-G1L Sites in Modified Vaccinia Virus Ankara After Serial Passage of Recombinant Vectors in Cells

“…pLW44-US6, pCAM17-US6 and pCAM18-US6 (1 µg each) were transfected into DF-1 cells that had been infected for 1 h with MVA at a multiplicity of infection (MOI) of 0.1, using X-tremeGENE HP DNA Transfection Reagent and protocol described by the manufacturer (Sigma-Aldrich, St. Louis, MO, USA). Recombinant MVA vectors-MVAdel3-gD2, MVA17-gD2 and MVA18-gD2-expressing gD2 from del III, CP77 and I8R-G1L sites, respectively, were isolated by 3 to 5 rounds of plaque purification, expanded in DF-1 cells and partially purified on 36% sucrose cushions as previously described [27,28].…”