IDENTIFICATION OF HUMAN CYTOMEGALOVIRUS STRAIN WITH IMMEDIATE-EARLY (IE) ANTIGEN-SPECIFIC MONOCLONAL-ANTIBODY IS PREVENTED BY POINT MUTATION IN IE GENE

In an AIDS patient with a disseminated human cytomegalovirus (HCMV) in fection, presence of HCMV in blood was repeatedly excluded by the shel l vial culture method with the HCMV immediate-early (IE) antigen-speci fic monoclonal antibody (MAb) 5D2 currently employed for rapid HCMV id entification, whereas it was repeatedly confirmed by all other assays (conventional virus isolation from blood, antigenemia, and DNAemia). S equence analysis of the HCMV strain revealed a point mutation in exon 2 of tile IE gene, which led to a serine-to-proline substitution at po sition 20 of the corresponding protein. Cloning and expression of a re gion of the IE gene containing the mutation showed that this was respo nsible for the lack of reactivity of MAb 5D2. A pool of IE antigen-rea ctive MAbs instead of a single MAb must be used for rapid HCMV identif ication to detect all viral strains.