Efforts were begun to adapt MAPREC as a potentially useful regulatory method for control of consistency of production of live viral vaccines other than OPV. High-passage samples of yellow fever virus vaccine (YFV) and of a cloned Jeryl-Lynn strain of mumps virus were obtained and subjected to sequence heterogeneity assay. Two nucleotide differences were identified in serially passaged YFV, and those mutations are now being studied quantitatively in various passage levels, and in commercial batches of YFV vaccine. A new mumps candidate vaccine strain, derived from the licensed Jeryl-Lynn vaccine strain, was completely sequenced, and that sequence was compared to another mumps strain the nucleotide sequence of which has been published. A high passage of the new Jeryl-Lynn strain was also sequenced. Serially passaged preparations of mumps vaccine viruses are now being compared to unpassaged vaccine virus preparations to identify unstable genomic sites suitable for monitoring the consistency of mumps vaccine production. The preliminary results of studies with mumps vaccine strains were presented by Guest Research Scientist at a meeting organized by his sponsoring organization.
