A recent study that appeared in the journal mBio (online open-access journal of American Society for Microbiology) shows that it may be possible to create a ‘universal’ vaccine that would aim to protect against a broad spectrum of influenza strains. Researchers at the National Institute of Allergy and Infectious Diseases (NIAID) claim to have created a virus-like particle vaccine that could be the possible solution for managing and avoiding future pandemics.
A New Vaccine Each Year
Every year, scientists develop a new flu vaccine against the predicted strain of the influenza virus that would be most common during that time of the year. Principal Investigator Jeffery Taubenberger, MD, PhD, Chief of Viral Pathogenesis and Evolution Section, Laboratory of Infectious Diseases, National Institute of Allergy and Infectious Diseases (NIAID) explained that if the vaccine prepared is even slightly different than the target virus, proper protection against a flu attack cannot be expected.
He stated that in this study, scientists have developed a strategy where matching the vaccine antigen with the virus is not a key issue.
Developing The ‘Universal’ Vaccine
Researchers at the NIAID used a ‘virus-like particle vaccine cocktail’. This mixture expressed a variety of subtypes of an important surface protein of the flu virus – hemagglutinin H1, H3, H5 and H7. Dr Taubenberger pointed out that there were at least 16 different subtypes of hemagglutinin found in birds, which were assumed to be the basis for present and future pandemics. The hypothesis of this study was that administering a mixture of these viral proteins would result in the stimulation of cross-protective immunity and broad-spectrum protection against numerous subtypes.
The reason for choosing H1 and H3 was based on them being the major causative agents behind seasonal flu outbreaks in humans since 1918. H5 and H7 were chosen because of their involvement in the recent bird flu outbreaks and potential future pandemics. Moreover, this selection ensured a broad-scale representation of hemagglutinins across the phylogenetic tree.
Promising Results in Mice
After various experiments, researchers observed that 95% of the mice vaccinated with their developed cocktail were protected against a fatal test of eight dissimilar flu strains which expressed seven different influenza A subtypes. This was seen in comparison to the 5% mice who received mock doses of the vaccine.
Dr Taubenberger highlighted that almost all of the vaccinated mice survived, including those that were challenged with viruses expressing hemagglutinins apart from those found in the vaccine, such as H2, H6, H10 and H11. “This suggests is that this approach really gives us broad spectrum protection, and could serve as a basis for an effective pre-pandemic vaccine”.
Further experiments demonstrated that the effects of the vaccine lasted for about six months, and it was durable and effective in older mice as well. The latter is especially important since the elderly are more susceptible to severe diseases after a flu infection, and presently available vaccines are not very efficacious in these individuals.
Dr Taubenberger conclusively stated that these initial findings show great promise for developing a practical strategy to create a vaccine with profound, broad-spectrum protective ability.