Figure 1.

Synthesis of five copies of M2e coding region with PCR.

Notes: (A) Primer-overlapping PCR for generating the coding sequence of five copies of M2e. The overlapping of fragments 1, 2, 3, and 4 eventually gives rise to a full-length M2ex5 through multiple cycles of PCR reaction. (B) Nucleotide and amino acid sequences of the M2ex5 coding region and polypeptide, respectively. Three glycine residues (boxed) were added in between each M2e gene, and also at both terminal ends of the M2ex5 gene as linkers. Underlined nucleotide sequences indicate overlapping region of primers used for gene synthesis. The nucleotide sequence was modified to have different sequences encoding for the same amino acids.

Abbreviations: PCR, polymerase chain reaction; M2ex5, nucleotide sequence encoding five copies of matrix 2 ectodomain of influenza A virus; M2e, influenza A matrix 2 ectodomain.