Lifelong immunity against all strains of the flu virus?
For the first time in the history of infectology, German scientists from the Friedrich Leffler Institute have created a vaccine, the active ingredient of which is an informational RNA molecule involved in the production of proteins. Unlike its predecessors, this vaccine, which provides the formation of lifelong immunity against influenza, can be produced quickly enough to stop the spread of a pandemic.
A person becomes immune to a strain of influenza virus if his immune system learns to recognize the proteins of the surface of the viral particle HA (hemagglutinin, hemagglutinin) and NA (neuraminidase, neuraminidase). This may be the result of a previous infection or vaccination with standard vaccines, most of which contain killed viral particles.
The flu virus is constantly evolving, so these proteins often change and immunity to one strain of flu does not provide protection in the future. For this reason, specialists have to develop a new vaccine every year. Most of the influenza vaccines are grown in chicken embryos or cell cultures, while the production process is stretched for at least 6 months.
This delay means that WHO has to predict the circulating strain several months before the start of the "season". Pharmaceutical companies produce vaccines based on these recommendations. It is obvious that forecasts may be inaccurate or, even worse, a pandemic may be caused by perfect new strains of the influenza virus.
Researchers working under the leadership of Lothar Stitz offer a fundamentally new solution to this problem, which is based on the use of mRNA that controls the production of HA and NA proteins. The new technology allows for several weeks to produce large quantities of the necessary mRNA, which is subsequently subjected to freeze drying. Unlike most vaccines, freeze-dried powder does not need to be stored at a reduced temperature.
When introduced into the body, mRNA is absorbed by immune cells, which translate it into the corresponding proteins. These proteins are recognized by the body as foreign, which leads to the formation of an immune response.
Earlier attempts were made to create vaccines based on DNA encoding viral proteins. However, the practical application of such vaccines will most likely never receive approval, since there is a danger of embedding viral DNA into the human genome, which can lead to a violation of the regulation of gene activity.
Unlike DNA, RNAs cannot be embedded in the genome, which determines the safety of their use. However, until now, testing of experimental RNA vaccines inevitably ended in failure, since they were quickly destroyed when they got into the blood. The specialists of the German company CureVac managed to cope with this problem, who discovered that the protamine protein is able to bind to mRNA and prevent its destruction. The company has used such complexes in the development of mRNA vaccines against prostate and lung cancer, currently undergoing clinical trials.
The authors applied this technology to create long-acting vaccines against common influenza strains, as well as against the so-called "bird flu" H5N1. In experiments on mice, ferrets and pigs, such vaccines provided the formation of protective levels of antibodies, that is, humoral immunity. Moreover, they triggered cellular immunity mechanisms implying the destruction of specific pathogens by activated blood cells, such as T-lymphocytes. Activation of the two main mechanisms of immunity provides faster destruction of infection and a longer period of protection from infection.
However, a truly universal flu vaccine should ensure the formation of immunity against proteins that are the same for all flu strains, which the virus usually hides from the immune system. Researchers have managed to create a vaccine against one of these proteins of the usual seasonal flu. This vaccine protected experimental animals not only from a specific strain of the virus, but also from the H5N1 virus.
The developers believe that over time, a single administration of such a vaccine can be included in the schedule of childhood vaccination. Currently, work is already underway to create an mRNA vaccine against rabies. The authors believe that mRNA is a universal platform for the development of vaccines against viral, bacterial and fungal pathogens.
Article by Benjamin Petsch et al. The protective efficacy of in vitro synthesized, specific mRNA vaccines against influenza A virus infection is published in the journal Nature Biotechnology.
Evgeniya Ryabtseva
Portal "Eternal youth" http://vechnayamolodost.ru based on the materials of New Scientist:
New vaccine may give lifelong protection from flu.
26.11.2012