Creating new antigens is a central theme in the Sanofi Pasteur strategy, according to Harry Kleanthous, the company’s associate vice president for research.
Sanofi Pasteur, the vaccines division of Sanofi, is actively developing more broadly cross-reactive antigens designed to protect people from pandemic and seasonal influenza.
“These new antigens are designed to retain key protective regions that are conserved across many more seasonal influenza strains,” Kleanthous told Vaccine News Daily. “Focusing people’s immune responses preferentially to these regions will result in broader immunity and increased strain coverage."
Specifically, Sanofi Pasteur’s experimental vaccine is a novel synthetic vaccine generated from key genetic sequences of many flu viruses. It is termed "computationally optimized broadly reactive antigen” (COBRA), which is designed to protect against many strains over several years.
The key is broader coverage against several seasonal flu strains, which is important when there is a mismatch to the vaccine strain.
“They are complementary but can be considered ‘tailored’ antigens in that they are designed to re-focus the immune response to key protective epitopes on the hemagglutinin, which is the active component of our currently licensed influenza vaccines,” Kleanthous said.
These antigens remain a key player in any flu vaccine because antibodies directed against them are responsible for preventing the flu virus from binding to and infecting the cell. Another advantage to this approach, he said, is not relying upon annual strain selection, meaning the company would be able to manufacture its vaccine year-round.
Kleanthous recently provided details about Sanofi Pasteur’s new universal influenza vaccine during the World Vaccine Congress held in Madrid. Following his presentation, he said “people found the concept of new synthetic HA-based vaccines designed to increase breadth of coverage a very rational and testable approach, especially as the approach relies upon current correlates of protection.”
Kleanthous also told Vaccine News Daily that congress attendees “also acknowledged the impact of harnessing people’s pre-existing immunity to flu as an important feature for inducing broadly protective responses.”
Sanofi Pasteur is working with Ted Ross, a leading infectious disease researcher at the University of Georgia, who is currently engineering COBRA vaccines based on past sequences to cover as many strains as possible and to maximize the immune response to an influenza vaccine.
“Improved influenza vaccines such as COBRA -- designed to protect against drifting and co-circulating viruses, as well as other antigens that induce complimentary mechanisms of protection -- are anticipated to have a significant impact on strain coverage and vaccine effectiveness,” Kleanthous said.