Dendritic representation of A subunit nucleotide sequence homology. The nucleotide sequence of the A-subunit-coding region of the following genes were compared: VT1 (nucleotide sequence accession no. M16625) (2), VT2 (nucleotide sequence accession no. X07865) (7), VT2vh-a and VT2vh-b (not present in databases) (6), VT2e (nucleotide sequence accession no. M21534) (39), VT2d-OX3a (nucleotide sequence accession no. X65949) (23), VT2d-O11 (nucleotide sequence accession no. L11078) (24), and VT2d-Ount (nucleotide sequence accession no. AF043627) (this study).