Transient expression of HA1 antigen of avian influenza virus (H5N1) in alfalfa, soybean and lettuce leaves by agroinfiltration

HA1 antigen is the major host protective immunogen of the highly pathogenic H5N1 avian influenza A virus (AIV), which leads to great pandemics and epidemics throughout the world. Plants are now gaining widespread acceptance as a general platform for the large scale production of recombinant proteins like influenza vaccines. In present study HA1 antigen of H5N1 was expressed in Alfalfa ( Medicago sativa), soybean ( Glycine max) and Lettuce ( Lactuca sativa) leaves using agro-infiltration. Also the effect of three signal peptide including KDEL, Extensin and ZERA which cause protein accumulation respectively in endoplasmic reticulum, apoplastic space and protein bodies, were analysed. 72 hours after the agro-infiltration, qRT-PCR results showed that lettuce and soybean respectively had the maximum and minimum of HA1 transcripts. The expression of HA1 was detected in leaves extracts by ELISA method. The highest expression was detected in alfalfa leaves with apoplastic signal peptide while the lowest expression was found in lettuce despite the highest transcription rate. The results showed that using agro-infiltration system in alfalfa plant with apoplastic signal peptide was the appropriate strategy for HA1 antigen production in the assayed plants.