Institut National de la Recherche Scientifique (INRS) View Institution's Website 2 articles published in JoVE Developmental Biology Competitive Transplants to Evaluate Hematopoietic Stem Cell Fitness Edward O. Kwarteng1, Krista M. Heinonen1 1INRS-Institut Armand-Frappier, Université du Québec, Institut National de la Recherche Scientifique This protocol provides step-by-step guidelines for setting up competitive mouse bone marrow transplant experiments to study hematopoietic stem/progenitor cell function without prior purification of stem cells by cell sorting. Biology Titration of Human Coronaviruses Using an Immunoperoxidase Assay Francine Lambert1, Helene Jacomy1, Gabriel Marceau1, Pierre J. Talbot1 1Laboratory of Neuroimmunovirology, INRS-Institut Armand-Frappier In this video, we demonstrate an alternative method for detection and titering of viruses using an enzymatic antigen detection technique known as an immunoperoxidase assay. Here, we will show you how to collect your viral samples, prepare the cells for testing, and finally the immunoperoxidase assay using serial dilutions to determine the viral titer.