More powerful vaccines for the flu developed
Two papers appearing in the Journal of Virology demonstrate the effectiveness of a flu vaccine candidate in animals. The research was carried out by scientists from the University of Georgia (UGA) and Sanofi-Pasteur.
The corresponding author of the papers Dr. Ted Ross, who is a professor at UGA, has been focused on the development of broadly reactive vaccines for different viruses, including influenza, HIV, and Dengue. In order to design new hemagglutinin (HA) vaccine immunogens, he employed a method known as computationally optimized broadly reactive antigen (COBRA) modeling. He pointed out that the production of influenza vaccines takes more than half a year at present. Essentially, it's impossible to predict which strains of influenza will be more predominant during the upcoming flu season. For these reasons, broadly reactive vaccines that can recognize multiple virus strains are needed to help us effectively beat the flu. In the current research, scientists got closer to achieving this goal by developing a vaccine that protects against all co-circulating strains of H3N2 viruses within several years.
H3N2 is a subtype of flu viruses. It mutates rapidly, changing a key protein on it that helps it escape human immunity. This is why we need novel vaccines every year. The rapid evolution of flu viruses makes them hard to handle. Analyses of DNA from many different flu virus strains have mapped how quickly each stain spreads throughout the world. It appears that the H3N2 strain is more and more abundant in seasonal influenza. What's worse, H3N2 has a reputation for being particularly deadly, which leads to more hospitalizations and death. This condition may be changed if we find more powerful vaccines.
Based on the genetic sequences of different flu virus strains, Dr. Ross' team generated a series of COBRA candidate vaccines and then tested them in mice and ferrets. The most effective vaccine regimens successfully elicited antibodies that could neutralize all co-circulating H3N2 variants from 2004-2007. The neutralization activity of these vaccines is much broader than conventional flu vaccines, which generally induce antibodies that neutralize merely the commonest viruses within one season. Collectively, the novel broadly reactive vaccines developed in this work might help us deal with the pandemic influenza.
On the other hand, Dr. Ross' team investigated how pre-existing immunity could affect the effectiveness of broadly reactive candidate vaccines. In response to pathogen invasion, the immune system in the body produces various substances like antibodies and immune cells to fight the enemy. After the infection, most of these substances and cells disappear, while some still remain. A vaccine is designed to stimulate a similar immune response against the pathogen. Previous studies have established that pre-existing immunity to certain pathogens affects how the body responds to a vaccine.
In summary, Dr. Ross' research offers a novel class of broadly reactive vaccines for influenza infection, although more work is still needed to assess these vaccines' efficacy and safety.