Nucleotide sequence analysis of Urabe mumps vaccine strain that caused meningitis in vaccine recipients.

Mumps virus was isolated from the cerebrospinal fluid of eight patients who acquired meningitis within 4 weeks of immunization with live Trivirix vaccine that contains mumps (Urabe Am 9), measles (Schwarz), and rubella (RA 27/3) viruses. Part of the haemagglutinin-neuraminidase (HN) gene from three postvaccination isolates of mumps virus, three wild strains and the Urabe and Jeryl Lynn vaccine strains was cloned following polymerase chain reaction (PCR) amplification, for the purpose of sequence analysis. A 200-nucleotide portion of the cloned HN genes was sequenced and compared to published sequences of two other strains (RW and SBL-1). The postvaccination mumps strains were identical in sequence to Urabe and were distinguishable from the wild and the Jeryl Lynn vaccine strains. Twenty-two out of 200 positions were seen to vary among the group of viruses. It was concluded that the Urabe vaccine strain was the cause of postvaccination meningitis. Therefore, with effect from 1990, Trivirix measles, mumps and rubella vaccine is no longer licensed for sale in Canada.