BackgroundCurrent vaccines against seasonal or pandemic influenza work by inducing antibodies to highly variable surface proteins of influenza.
The vaccines have to be reformulated each year to take account of antigenic drift and shift.
Information on the viruses to be included in the vaccine is only available a few months before the vaccine is required for use, so that manufacturers have a limited time to produce the vaccine. If delays in the process occur there will be shortages of vaccine for that year.
Aim: A universal flu vaccine
At the Jenner Institute we are working on an entirely different approach to influenza vaccination, based on T cell immunity to the highly conserved internal antigens of influenza. We aim to generate a vaccine suitable for use in all ages, providing protection against currently circulating seasonal influenza as well as avian subtypes that may in future gain the ability to transmit between humans and bring about a new pandemic.
Clinical trials of Modified Vaccinia virus Ankara expressing conserved influenza antigens (MVA-NP+M1) began in Oxford in 2008. The first trial assessed safety and immunogenicity of the vaccine at different doses and this has now been published (Berthoud et al., 2011). Following positive results in that study, we went on to conduct an influenza challenge study in which half of the volunteers were vaccinated, half were not, and all were subsequently infected with influenza to test if the vaccine protected them. There was a significant reduction in duration of virus shedding in the vaccinated volunteers, and fewer vaccinated than non-vaccinated volunteers developed laboratory-confirmed influenza (Lillie et al., 2012).
Another trial tested the effect of giving MVA-NP+M1 at the same time as a licensed influenza vaccine, trivalent inactivated vaccine (TIV). Pre-clinical studies have shown that as well as boosting T cells recognising the influenza antigens included in the vaccine, antibody responses to TIV were also increased. This could be an easily deployable solution to improving the immunogenicity of TIV in older adults, and results from this trial will be available during 2012.
A new vaccine using a simian adenovirus vector developed in Oxford to express conserved influenza antigens is also being developed and the first clinical study with this new vaccine has now started.