Development of high yield reassortants for influenza type B viruses and analysis of their gene compositions

Highlights • High yield (hy) reassortant influenza B seed viruses for vaccine production can be developed through classical reassortment of wild type (wt) B isolates with B/Lee/40 as the hy donor virus. • A detailed method of generating hy influenza B reassortants is presented. • On average hy reassortants increased the HA titers over their wt counterparts by 8 fold. • NP and PB1 of the B/Lee/40 were important for Victoria lineage reassortants while NP, PB1 and PB2 from B/Lee/40 along with NS from wt were important contributors for hy growth of the Yamagata lineage reassortants.