Background and Aims: Influenza vaccine production process is time-consuming with little-to-no cross-protection which requires annual adjustment. The construction of a universal vaccine to deal with the pandemics and epidemics which occasionally threat human population is the aim of many researches worldwide. Today, influenza vaccines are mostly against two major antigenic proteins, hemagglutinin and neuraminidase. As compared to high variable globular head, the hemagglutinin stalk domain is more conserved among different subtypes of influenza A viruses which could be a good candidate to develop a cross-protective vaccine.
Materials and Methods: In this study, recombinant HA2 protein comprising fusion peptide was expressed in E.coli, purified using Ni-TED columns, refolded and desalted by dialysis. BALB/c mice in different groups were immunized with HA2 alone or supplemented with Alum or Alum/CPG. Vaccinated mice sera were examined for anti-HA2 specific IgG responses. Finally, mice were challenged with one LD90 of mouse-adapted A/PR8 virus.
Results: The results showed that HA2 recombinant protein could provoke immunogenicity in BALA/c mice and this immune response could be elevated with Alum and Alum/CpG. Despite promising immune responses, there was insignificant protection of HA2-immunized mice when challenged with the mouse-adapted strain A/PR8.
Conclusions: Therefore, HA2 protein alongside with other influenza virus conserved proteins should be studied to achieve a suitable vaccine formulation for broad spectrum cross-reactive immune responses.

Background and Aims: The aim of this study was to produce and purify the Polyclonal antibody (pAb) against Matrix protein 2 (M2) with reasonable efficiency. Matrix protein 2 is one of the most conserved proteins of the influenza A virus which acts as ion channel. Polyclonal antibodyproduced against Matrix protein 2 is used in vaccine research, passive immunization and qualitative/quantitative analysis methods.
Materials and Methods: Recombinant M2 protein was produced in E.coli. Purified protein with Freund’s adjuvants (Complete and Incomplete) was injected into two New-Zealand white male rabbits. The polyclonal antisera of rabbits were evaluated by RID, immunoblotting and ELISA. The IgG was purified using DAEA-cellulose column chromatography. Finally, the quality and properties of purified IgG were evaluated using SDS-PAGE and ELISA.
Results: The RID and immunoblotting results showed that the produced anti-M2 antibody was able to recognize M2 recombinant protein epitopes. The ELISA results confirmed anti-M2 pAb reached reasonable titers after three injections. IgG against M2 was purified with suitable concentration. The Purified polyclonal IgG-M2 was evaluated using ELISA and the results showed IgG-M2 reacted with the antigen up to 1:32000.
Conclusions: The data showed that recombinant M2 protein was able to stimulate immune response to produce antibody at satisfactory level.