MOLECULAR-IDENTIFICATION OF 2 DISTINCT HEMAGGLUTININ TYPES OF MEASLES-VIRUS BY POLYMERASE CHAIN-REACTION AND RESTRICTION-FRAGMENT-LENGTH-POLYMORPHISM (PCR-RFLP)

Contemporary isolates of measles virus, characterized by their inabili ty to hemagglutinate, have been shown to possess a hemagglutinin type distinct from that of classical strains such as the Edmonston strain i n that there is a new glycosylation site at amino acid residue 416. Th is change abolishes a Sau3Al site that is found in the corresponding p osition of the hemagglutination-positive classical strains. This molec ular information prompted us to develop a restriction fragment length polymorphism (RFLP) assay that is capable of distinguishing these two distinct hemagglutinin types. The assay consists of the amplification of a 349-bp segment of the hemagglutinin gene by reverse transcription followed by the polymerase chain reaction and Sau3Al digestion of thi s amplification product. The resulting two distinct RFLP patterns iden tified the hemagglutinin types with regard to the presence or absence of the potential new glycosylation site. This assay was applied to det ermine the relative frequencies over a 28-year period of these two hem agglutinin types present in the archival acute serum specimens taken f rom patients with measles. This study revealed that strains carrying t he classical hemagglutinin type predominated until the early 1980s whe n it became completely replaced with strains possessing the contempora ry hemagglutinin type. Because of its direct applicability to the clin ical specimens avoiding selection bias during cell-culture adaptation, this assay provides a valuable asset in both clinical laboratory and epidemiological settings.