GENETIC STABILITY OF COLD-ADAPTED A LENINGRAD/134/47/57 (H2N2) INFLUENZA-VIRUS - SEQUENCE-ANALYSIS OF LIVE COLD-ADAPTED REASSORTANT VACCINESTRAINS BEFORE AND AFTER REPLICATION IN CHILDREN/

We previously reported that the A/Leningrad/134/47/57 (H2N2) cold-adap ted virus (A/Len/47) used in preparing reassortant live attenuated vac cines for children acquired 14 (11 coding) mutations in genes coding f or proteins other than haemagglutinin and neuraminidase during cold-ad aptation. Preservation of these mutations in genomes of viruses isolat ed from children on the second, fifth, or eighth day after vaccination was examined by sequence analysis. The sequence data demonstrated tha t all nine coding mutations selected for examination were conserved in the genomes of all 11 strains investigated, indicating that the mutat ions accompanying cold-adaptation and attenuation of the A/Len/47 mast er vaccine are highly stable.