MVA titration by plaque assay using crystal violet staining in DF-1 cells

Modified Vaccinia Ankara (MVA) is a highly promising vector for generating safe vaccine candidates against many pathogens, such as HIV-1, SARS-CoV-2, and influenza viruses. The gold standard method to titrate MVA involves visualizing MVA plaques in chicken embryo fibroblasts after immunostaining. However, this method is time-consuming and costly. In this study, we evaluated the visualization of MVA plaques formed in continuous chicken embryo fibroblasts DF-1 cells using crystal violet staining. We found that MVA titration by plaque assay using crystal violet staining in DF-1 cells yielded similar results to immunostaining, with substantially reduced time and costs. The MVA plaque assay by crystal violet staining in DF-1 cells is a reliable method with accurate results and low time and financial costs.