Immune Response in Mice Immunized with Chimeric H1 Antigens

Identification of a universal influenza vaccine candidate has remained a global challenge for both humans and animals. This study describes an approach that uses consensus sequence building to generate chimeric HAs (cHAs): two resultant H1 HA-based chimeras comprising of conserved sequences (within several areas spanning the head and stalk regions) of H1 and H5 or H9 HAs. These cHAs expressed in Drosophila cells (S2) were used to immunize mice. All immunized mice were protected from an infectious H1 virus challenge. Seroconverted mice sera to the H1 cHAs inhibited both the challenge virus and an H5 virus isolate by haemagglutination inhibition (HI) assay. These findings further emphasize that cHAs induce cross-reactive antibodies against conserved areas of both head and stalk regions of the seasonal influenza A (H1N1) pdm09 virus’ HA and holds potential for further development of a universal influenza vaccine

A sample gel image.

(PDF)</p

HA amino acid alignment for influenza B Victoria-lineage viruses.

(PDF)</p

Potential glycosylation sites of influenza B Victoria HA genes.

(PDF)</p

Phylogenetic analysis of influenza B Yamagata lineage using the HA genes.

Bootstrap values over 80% are indicated on the tree. Red represents the WHO vaccine candidate virus genome, pink represents reference Ghanaian specimens sequenced at the Francis Crick Institute, blue represents the sequences we identified, green represents the deletion sub-group, Amino acid changes in black represent those within HA1, with violet representing changes in the HA2.</p

Potential glycosylation sites of influenza B Yamagata HA genes.

(PDF)</p

Details of primers used for this research.

(PDF)</p

Phylogenetic analysis of influenza B Victoria lineage using HA genes.

Bootstrap values over 80% are indicated on the tree. Red represents the WHO vaccine candidate virus genome, pink represents reference Ghanaian specimens sequenced at the Francis Crick Institute, blue represents the sequences obtained from our retrospective analysis, green represents the deletion sub-group, Amino acid changes in black represent those within HA1, with violet representing changes in the HA2.</p

Lineage specific markers of influenza B HA gene.

Multiple sequence alignment was carried out using ClustalW in BioEdit with a boostrap replicates of 1000 in line with Edgar [16]. Influenza B/Brisbane/60/2008 was used as the reference sequence for B/Victoria lineages while B/Wisconsin/1/2010, Clade 3 and B/Massachusetts/2/2012, Clade 2 were used as the reference sequence for B Yamagata lineages. Influenza B virus lineage-specific markers (nts 522, 540–542, 548, 549, 555, 558 and 568) are shown in yellow, whereas the clade specific markers (nts 538, 562 and 589) have been highlighted as green.</p

A schematic of primer locations on the influenza B HA gene.

A schematic representation of the influenza B HA gene showing overlapping fragments and their expected sizes in base pairs. All sixteen primers and their corresponding eight fragments are shown. Red and green colors indicate fragment numbers and expected sizes, respectively.</p