FIG 3.

Introduction of a genetic marker into the Orsay virus genome. (A) Design of an Orsay virus genetic marker in its RNA1 genome segment. Arrows indicate the position where primers were used to perform RT-PCR. Letters in green highlight the three synonymous point mutations introduced, with asterisks indicating their positions in the genome. (B) RT-PCR and PCR spanning the mutated locus. RNA was extracted from three C. elegans cultures infected by three independent mutant virus filtrates. The expected PCR band is ∼600 bp. M, molecular size marker. (C) The genetic marker was preserved in the recombinant virus as shown by the Sanger sequencing chromatogram of the three mutant viruses. Aligned boxes indicate the genetic marker.