Abstract: The invention relates to the use of a single heavy chain variable domain antibody against human cytomegalovirus protein US28, which antibody binds to the extracellular region including, for example, the N-terminal extracellular region and/or the extracellular loops of US28, for isolation of cells that are infected with cytomegalovirus and/or for ex vivo reactivation of cytomegalovirus in latently infected cells. The invention further relates to the anti-US28 antibody for use in a method of reactivating cytomegalovirus in infected cells, or in a method of eliminating infected cells. The invention further relates to a tissue, organ, or cells such as bone marrow stem cells, from which cells that were infected with CMV have been removed with the use of the anti-US28 antibody.