CD71 targeting boosts immunogenicity of sublingually delivered influenza haemagglutinin antigen and protects against viral challenge in mice
Vaccines are complicated. The research and development, the pricing, the delivery (getting them to the right people), the acceptance (getting the right people to take them) are all complicated. Vaccines are unlike other forms of medicine because they are universally prescribed as a preventative rather than a cure. When vaccines are successful, they can be self-defeating because they reduce the disease and therefore the fear of the disease, which gets people to use them in the first place.
Vaccine uptake varies for various sensible and less sensible reasons, which you can track live at the vaccine confidence project run by the London school of hygiene and tropical medicine. One reason for poor vaccine uptake is fear of needles and therefore one approach to improve vaccines is to develop vaccines that don’t need needles.
Going needle free
Finding alternatives to needles is more than a ‘first world problem’. There has been, historically, an issue with the re-use of dirty needles and the spread of blood borne diseases. This has been reduced by moving to syringes that can only be used once. Vaccines without needles may also be scientifically better. Delivering vaccine to the site of infection (or mucosal delivery) can improve the response to the vaccine. The mucosa refers to internal body surfaces that face the outside (and have mucus): it includes the nose and lungs, mouth, stomach and guts and genital tract. These tissues are a major route into the body for a wide range of infectious organisms, so require extra vigilant immunity. But, critically, mucosal surfaces are sites of exchange (lungs – oxygen, guts – food, genitals – babies). They therefore need to be porous enough to allow in beneficial material but not so porous that bugs can get in. Balancing these two needs leads to specialised immune responses at mucosal surfaces. In our current study: “CD71 targeting boosts immunogenicity of sublingually delivered influenza haemagglutinin antigen and protects against viral challenge in mice”, we exploited our knowledge of mucosal immunology to develop better vaccines.
On the tip of your tongue
Paul and Jamie (co-authors on the paper) have previously shown that targeting a specific molecule called the transferrin receptor (whose normal purpose is to pump iron into the body, also known as CD71) can improve the quality of vaccine responses. It has been shown that applying vaccines under the tongue (sublingually) can lead to a better response. The current study looked at combining these two approaches – targeting the transferrin receptor on the tongue to deliver vaccines. When used, the immune response to influenza was significantly improved, leading to a more protective vaccine. This approach could be used for a range of diseases, removing needles and improving the response.