Researchers come up with alternative approach to universal flu vaccine

Sequentially vaccinating individuals with distinct influenza strains isolated from the last century could be one approach to providing resistance to seasonal and pandemic influenza strains over many years, according to a recent study.

Researchers at the Philadelphia-based The Wistar Institute found that different aged people mounted vastly different antibody responses to pandemic H1N1, depending on whether or not they were previously exposed to a seasonal H1N1 strain years earlier. The 2009 H1N1 virus was a distant relative to the devastating Spanish Flu of the early 20th century.

"Our studies demonstrate that individuals that are infected sequentially with dramatically different influenza strains mount antibody responses against a conserved region of influenza virus," Scott Hensley, the corresponding author of the study, said. "Since we now know that pre-exposure events can influence vaccine responsiveness in a predictable way, we can begin to design vaccine regimens that preferentially elicit antibody responses against conserved regions of influenza virus."

The researchers found that by infecting ferrets with historical influenza strains, they were able to shift the antibody response toward the epitope that human antibodies recognize. The team said that the shift might be replicable in humans through multiple vaccinations or infections.

"Babies are born with an immunological blank slate," Hensley said. "We may be able to strategically vaccinate our children with antigenically diverse influenza strains to elicit antibodies against conserved viral epitopes."

The analysis could result in a new approach to creating a universal flu vaccine, a vaccine that would negate the need for an annual flu shot by providing resistance to many different strains.

Despite the availability of flu vaccines, seasonal influenza usually kills approximately 36,000 Americans per year and close to 500,000 people worldwide.