Gotovax AB is a leading innovator in the field of antigen development and has filed a patent (PCT/SE2010/050996 Vaccine against Cholera and Enterotoxigenic Escherichia Coli (ETEC) against Diarrhoea) that is based on evidence that immunisation of already infected animals with appropriate amounts of two selected protective Helicobacter pylori antigens (i.e., HpaA and urease) gives rise to stronger protection compared to immunisation even with lysed Helicobacter pylori bacteria. However, due to safety concerns this approach has not received the regulatory approval required for widespread clinical use.
The Gotovax patent application protects an innovative, non-pathogenic Vibrio cholerae vaccine strain, engineered to express high amounts of the selected Helicobacter pylori antigens; HpaA, UreB, and FlaA or B. They are considered important for the following reasons:
- HpaA is found on the surface of the bacteria and is also an essential colonization factor
- Urease, with the UreB as its major subunit, protects the bacteria from luminal acidity and that in turn helps the bacteria to colonize
- Fla A and B are the proteins that build up the flagellae that are needed for colonisation and infection
After induction the bacteria are easily inactivated with formalin without loss of the expressed antigens and can be used as vaccine candidates. The HELICOVAXOR™ project is also evaluating the inactivated strain Helicovaxor pylori Hel-305.
A further innovation relates to manufacturing efficiency. The selected bacteria (Vibrio cholerae) grow quickly to high densities and are engineered to negate the need for downstream protein purification.
To overcome the fact that Helicobacter pylori colonizes the gastric mucosa making the bacterium inaccessible to many immune effector mechanisms, Gotovax further modifies recombinant bacterial strains to express specific attachment proteins for the sites where the immune response should be initiated.