BioSante Pharmaceuticals has announced positive results of a dose ranging pre-clinical study demonstrating that its calcium phosphate (CaP) nanoparticle-based vaccine adjuvant, BioVant(TM), may serve as a vaccine adjuvant for the development of an effective vaccine against H5N1 avian flu, widely known as bird flu.
BioSante's pre-clinical study's objective was to determine the optimal formulation of BioVant with a very low dose of H5N1 antigen. At the start of the 16-week pre-clinical trial, mice received either the H5N1 antigen alone or in one of several formulations with BioVant, as well as various control groups. A booster immunization was administered after two and 10 weeks. Results showed that the administration of a BioVant/H5N1 formulation stimulated a significantly higher production of titers of H5N1-specific antibodies than H5N1 alone. Further, the anti-bird flu antibody levels continued to increase over the entire study period, suggesting good duration of immunity.
"Recent news suggests that bird flu has not gone away. We continue to make progress in our adjuvanted H5N1 vaccine development," said Stephen M. Simes, president and chief executive officer of BioSante. "A vaccine with an adjuvant included may allow for better efficacy and lower doses per vaccination which may help to prevent shortages. More importantly, the addition of an adjuvant may enable a higher percentage of people inoculated to produce an immune response and protect them from disease."
"Coupled with our previously announced results using a BioVant adjuvanted H5N1 vaccine delivered intranasally, we believe this dose ranging study further confirms the potential of BioVant to be used as part of a dose sparing, easier to administer, non-injected vaccine, which we believe could garner wider compliance in initial and booster administration," Simes said. "We hope to move into additional pre-clinical trials and attract a vaccine manufacturer to use BioVant in a new flu vaccine."
Bird flu refers to a large group of different influenza viruses that primarily affect birds. While the vast majority of these viruses do not affect humans, the H5N1 strain has already made the jump from birds to humans and in fact, has infected 270 people and killed 164 since December 2003. There is widespread concern that a strain of bird flu will mutate into a new form that is contagious among humans. Since there is currently no vaccine available to protect humans from H5N1 and humans do not have antibodies to fight this new virus strain, there is significant risk of a pandemic.
BioVant is composed of specially formulated calcium phosphate, a compound similar to that found in teeth and bones. In multiple studies, BioVant has been shown to be safe and cause minimal dose-dependent inflammation at the injection site. As opposed to the conventional vaccine adjuvant alum, BioVant induces insignificant immunoglobulin E (IgE) and higher serum IgG2a levels, a reaction that is widely recognized as a precursor of a Th1 CD4 T-cell response. Th1-type responses are known to promote immunity against intracellular pathogens.
"We believe CaP, in the form of BioVant, shows potential to be an important adjuvant for the next generation of vaccines against both viral and bacterial infections," Simes said. "In addition to the bird flu vaccine, BioSante is pursuing additional collaborations and licenses for further development of CaP in both vaccines and drug delivery."