Purification of Influenza virus A (H1N1) recombinant Hemagglutinin (HA1) and polyclonal antibody production

Each year, Human influenza A (H1N1) virus causes moderate to severe infections with a high prevalence throughout the world. Accordingly, the rapid, sensitive and cost-effective laboratory diagnosis based on viral antigen detection is important. Moreover, the generation of specific antibodies directed against Influenza antigens is essential to the success of both basic and applied research programs. Hemagglutinin (HA) is the major surface envelope glycoprotein of influenza virus, which is subsequently cleaved into two subunits, HA1 and HA2. Since most antigenic sites are in the HA1 domain of HA, HA1 domain of influenza virus was studied as antigen to produce polyclonal antibody.
In this experimental study we expressed and purified the recombinant HA1 protein in the second half of 2015 at department of influenza and other respiratory viruses, Pasteur Institute of Iran and then prepared the polyclonal rabbit antibody against it. The vector of pET28aHA1 expressing HA1-His tagged protein of H1N1 influenza A/PR/8/34 virus was used for large scale production of HA1 into E. Coli (BL21). By changing expression conditions such as IPTG (Isopropyl β-D-1-thiogalactopyranoside) concentration, time and temperature of incubation, the expression conditions for HA1 were optimized. The total cell protein harvested and purified by nickel affinity chromatography. All above mentioned experiments monitored by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE).
The efficiency of HA1 recombinant protein was high, equal to 400-600 mg/ml of cell lysate. The polyclonal antibody was prepared by immunizing the rabbits using recombinant HA1 with Freund’s adjuvant according to standard protocols. Efficiency of the antiserum evaluated by enzyme linked immunosorbent assay (ELISA). Determination of antibody level in the collected antiserum using serum-based ELISA showed that the specific antibody has risen well through the immunization schedule.
Our data shows that this polyclonal antibody has potential to be produced in rabbit. It will also be used in the future in influenza diagnosis as well as in other immunological applications such as western blot analyses, immunocytochemistry, and immunohistochemistry.