doi:10.1038/nindia.2011.189 Published online 22 December 2011
Researchers have used an yeast as a platform for recombinant expression of the Hemagglutinin (HA) protein of pandemic Influenza A virus H1N1. The protein neutralises the virus and protects against infection. The researchers say this yeast platform can be successfully used as an alternative for large-scale production of recombinant influenza HA protein to fight the influenza pandemic threat.
Commercially available Influenza A vaccines have serious impediments such as limited availability, risk of allergic reactions and time consumption. This has hindered their potential to meet the demand of rapid global vaccination required to combat pandemics.
HA being a glycosylated protein poses a serious challenge for heterologous expression in native trimeric conformation and demands an eukaryotic expression platform.
Considering the advantages of Pichia pastoris, one of the most successful yeast expression systems used for making several therapeutic proteins and vaccines, the researchers used it for recombinant expression of H1N1 HA protein. The HA gene of novel H1N1 A/California/04/2009 was engineered for expression in Pichia pastoris as a soluble secreted protein. The full length HA-synthetic gene having α-secretory tag was integrated into the yeast genome via homologous recombination. The resultant Pichia clones with multiple copy integrants of the transgene expressed full length HA protein.
Culture conditions necessary for optimum expression of the recombinant HA protein were optimized by using shaker flask culture and fed batch fermentation. The recovered HA protein was present in its native trimeric conformation.
Mice and rabbits immunized with the yeast expressed HA protein were found to produce neutralizing antibodies. The sera from immunized animals also exhibited Hemagglutination Inhibition (HI) activity thus demonstrating the prophylactic potential of the yeast derived recombinant HA protein.
The researchers say this yeast platform is is safe, reliable and cost effective.