Development and Identification of a Live Attenuated Influenza B Virus Vaccine Candidate*

Abstract

A cold-adapted (ca), temperature sensitive (ts), live attenuated influenza B virus strain B/Ann Arbor/1/66 was chosen influenza virus rescue research, in which six internal gene segments, PB 1, PB2, PA, NP, M, NS, were fully synthesized and nine amino acid substitutions were artificially alter by human intervention. The resultant B/Ann Arbor/1/66 plasmids were named as pAB121-PBI, pAB 122-PB2, pAB 123-PA, pAB 124-HA, pAB 125-NP, pAB126-NA, pAB 127-M and pAB 128-NS, respectively. A recombinant influenza A virus was previously generated entirely from cloned eDNA. An infectious recombinant influenza B virus was generated here, and designated as rMDV-B, by plasmid-based reverse genetics. The rMDV-B virus contained HA and NA genes from epidemic influenza B virus strain B/MalaysiaJ2506/2004 in the background of internal genes derived from influenza B vims strain B/Aim Arbor/1/66. HA titer of rMDV-B in MDCK cells and embryonated chicken eggs ranged from 1 64 to 1 512. The results may allow an effective live influenza B vaccine to be produced from a single master strain, providing a model for the design of future human influenza vaccines.