CLONING AND CHARACTERIZATION OF THE CDNA-ENCODING THE HA PROTEIN OF AHEMAGGLUTINATION-DEFECTIVE MEASLES-VIRUS STRAIN

cDNA clones corresponding to the mRNA for the hemagglutinin of the hem agglutination-defective strain AK-1 of measles virus were isolated and characterized. Compared with the prototype Edmonston strain, 60 nucle otide substitutions that resulted in 18 amino acid changes were detect ed. An additional potential N-linked glycosylation site was added by p oint mutation, which was supported by the observation that the hemaggl utinin of the AK-1 strain was stained more heavily after NaDodSO(4). P AGE and periodic acid-Schiff (PAS) staining than the Edmonston strain. Computer-assisted analysis revealed that three reverse turns in the s econdary structure had disappeared in the hemagglutinin of the AK-1 st rain. Moreover, one of these structural changes occurred in the closel y glycosylated region at amino acid residues 168-240, which appeared t o be a biologically important functional domain. The isoelectric point calculated from the predicted amino acid sequence became about 1 pH u nit more basic in the AK-1 strain than the Edmonston strain. This pres ent study is the first sequence analysis of the hemagglutinin gene in a hemagglutination-defective strain of the measles virus.