Researchers at the Icahn School of Medicine at Mount Sinai believe that a new method they've developed called chimeric hemagglutinin (cHA) will help in the development of a universal flu vaccine.
Hemagglutinin, a protein on the surface of influenza viruses, shepherds the virus into host cells; it is composed of a “head” (variable) and a “stalk” (varies less from strain to strain). The team has focused their efforts on developing a vaccine against the stalk portion of this protein, and their study published today in The Lancet Infectious Diseases specifically investigated whether several potential cHA-based vaccines might induce antibodies that would target the stalk of group 1 hemagglutinin-expressing influenza viruses.
Vaccine regimens examined included: 1) a group receiving a chimeric H8/1 hemagglutinin-based live attenuated vaccine followed by a boost with a non-adjuvanted chimeric H5/1 hemagglutinin-based inactivated vaccine (IIV), and 2) the same regimen but with the IIV having an adjuvant called AS03, and 3) a prime-boost regimen including an adjuvanted cH8/1 IIV prime followed by an adjuvanted cH5/1 IIV boost.
The researchers found that the IIV, but not the live attenuated vaccine, induced a significant antibody response after the prime, with a strong increase in anti-H1 stalk titers. All vaccine regimens induced detectable H1 stalk antibody responses after receiving boosts.
"The vaccine induced a broad antibody response which was not only cross-reactive for currently circulating human influenza virus but also to avian and bat influenza virus subtypes," said senior author Florian Krammer. "It was surprising to find that the inactivated formulation with adjuvant induced a very strong anti-stalk response already after the prime suggesting that one vaccination might be enough to induce protection against pandemic influenza viruses yet to arise. The results indicate that we are moving towards a universal influenza virus vaccine, but these are still interim results. Additional results will be available upon completion of the study at the end of 2019."