Construction of a reassortant influenza B virus with reverse genetics system

Objective To construct a reverse genetic platform for influenza B virus and to rescue influenza B virus. Methods Eight plasmids carrying the gene segments of B/Florida/4/2006 virus were constructed by using the bidirectional promoter vector pHW2000. 293T cells were co-cultured with Madin-Darby canine kidney (MDCK) cells and then transfected with the eight plasmids. The supernatants of cell culture and cell debris were collected after transfection and then injected into embryonated chicken eggs and MDCK cells for rescuing the influenza B virus strains. Results This reverse genetic system could be used for the preparation of reassortant influenza B virus strains. The titers of hemagglutination units of the rescued virus achieved 128-256/50μl. Most of the reassortant virus particles were spherical under electron microscope. Conclusion The pHW2000 reverse genetic system could be used for the rescue of influenza B virus. Moreover, it could also be used for the construction of influenza B virus with specific mutations for further investigation on the characteristics of influenza B virus and the construction of vaccine strain. Key words: Influenza B virus; Reverse genetics; Recombination; Reassortant