Influenza is a viral infection that affects mainly the nose, throat, bronchi and, occasionally, lungs. Infection usually lasts for about a week, and is characterized by sudden onset of high fever, aching muscles, headache and severe malaise, non-productive cough, sore throat and rhinitis.
Annually thousands of people die due to flu related problems. Vaccination is the only way to protect the spread of influenza virus. But existing vaccines work only against the narrow set of flu strains that the vaccine makers predict will dominate in a given year. Therefore they bring effectiveness temporarily. Lately, scientists at the Scripps Research Institute and the Dutch biopharmaceutical company Crucell have discovered broadly acting antibody against influenza virus which may offer hope for a near-universal flu vaccine.
In generally, current influenza vaccines provide little or no protection against unforeseen strains. Flu virus has a basic defense mechanism. The Crucell scientists conducted this research to find and and attack relatively unvarying and functionally important structures on flu viruses.
By sifting through the blood of people who had been immunized with flu vaccines, the scientists discovered an antibody that bound to one such vulnerable structure. This antibody called CR6261, could prevent or cure an otherwise-lethal infection by about half of flu viruses in mice, including H1 viruses such as H1N1, strains of which caused deadly global pandemics in 1918 Spanish Flu and 2009 Swine Flu global pandemics.
In 2009, Wilson team showed the influenza subtypes neutralized with the new antibody include H3N2, strains of which killed an estimated one million people in Asia in the late 1960s. The Crucell researchers approached Wilson’s findings and discovered the binding site, or “epitope,” turned out to be on HA’s lower, less-accessible stalk portion and the binding of CR6261 to that region apparently interferes with flu viruses’ ability to deliver their genetic material into host cells and start a new .
The Crucell researchers wanted to look for an antibody that could neutralize all of the remaining flu viruses unaffected by CR6261. They furthermore found one CR8020, which they say powerfully neutralizes a range of human-affecting flu viruses, including H3 and H7 subtypes, in lab-dish tests and in mice. They utilized the same technique used with CR6261 and determined the antibody’s structure and its precise epitope on the viral HA protein.
The scientists hope if tests of the CR6261 and CR8020 antibody in human volunteers are successful, a vaccine the two antibodies could be combined and used in a “passive immunotherapy” approach. Its ultimate goal is to create an active vaccine that elicits a robust, long-term antibody response against those vulnerable epitopes.