iBIO next news. The human potential of a recombinant pandemic influenza vaccine produced in tobacco plants
Human Vaccines and Immunotherapeutics
Volume 8, Issue 5 May 2012
Rapid production of influenza vaccine antigen is an important challenge when a new pandemic occurs. Production of recombinant antigens in plants is a quick, cost effective and up scalable new strategy for influenza vaccine production. In this study, we have characterized a recombinant influenza haemagglutinin antigen (HAC1) that was derived from the 2009 pandemic H1N1 virus and expressed in tobacco plants. Volunteers vaccinated with the 2009 pH1N1 oil-in-water adjuvanted vaccine provided serum and lymphocyte samples that were used to study the immunogenic properties of the HAC1 antigen in vitro. By 7 d post vaccination, the vaccine fulfilled the licensing criteria for antibody responses to the HA detected by haemagglutination inhibition and single radial hemolysis. By ELISA and ELISPOT analysis we showed that HAC1 was recognized by specific serum antibodies and antibody secreting cells, respectively. We conducted a kinetic analysis and found a peak of serum HAC1 spec antibody response between day 14 and 21 post vaccination by ELISA. We also detected elevated production of IL-2 and IFN? and low frequencies of CD4+ T cells producing single or multiple Th1 cytokines after stimulating PBMCs (peripheral blood mononuclear cells) with the HAC1 antigen in vitro. This indicates that the antigen can interact with T cells, although confirming an effective adjuvant would be required to improve the T-cell stimulation of plant based vaccines. We conclude that the tobacco derived recombinant HAC1 antigen is a promising vaccine candidate recognized by both B- and T cells.
The final analyses confirm the results of the June 2, 2011 announcement of the safety and immunogenicity of the HAC1 vaccine which was found to be safe and well tolerated at all dose levels, with or without adjuvant. There were no reported serious adverse events or dose-limiting toxicities. No subjects withdrew from the study as a consequence of an adverse event. The analyses also showed that the HAC1 vaccine elicited high levels of immune responses which correlated directly with the amount of antigen administered when the vaccine was not adjuvanted. The immune response was the highest in subjects who received the non-adjuvanted highest HAC1 dose which was comparable with the immune response of the licensed, control H1N1 vaccine.
A manuscript is under preparation to be published in a peer-reviewed journal.
iBio Announces Successful Completion of H1N1 Influenza Vaccine Phase 1 Clinical Trial
Safety and reactogenicity assessments were completed at WRAIR-CTC and immunogenicity evaluation was performed by the Influenza Division of the Centers for Disease Control and Prevention.
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