Determination of HSV-1 UL5 and UL29 gene copy numbers in an HSV complementing Vero cell line.

•There are challenges with conventional methods to show stability of the transgenes.•The stability of the transgenes in AV529 cell line was assessed by dPCR approach.•A similar number of gene copies were detected in AV529 MCB and in the AV529 ECB.•These results confirm throughout population of AV529-19 beyond the production run.