In order to evaluate the contribution of V2 to the viral infection, we generated an infectious TYLCV clone carrying a G-to-A mutation in the fifth nucleotide of the V2 open reading frame (ORF), which converts the second codon (encoding tryptophan) to a stop codon (Figure 2—figure supplement 2), making it unable to produce the V2 protein (TYLCV-V2null). This evidence concerns the gene TRGV9 and viral infectious disease.