A new form of mRNA vaccine produces a stronger and longer-lasting immune response than the traditional variant. He achieves this effect with a significantly lower vaccination dose. The two biotechnology companies Arcturus Therapeutics (from the USA) and CSL (from Australia), which developed the vaccine, reported this at the beginning of February. The test subjects boosted with the new vaccine produced more antibodies, which also patrolled the body for longer.
Advertisement
Similar to previous mRNA vaccines, the new vaccine provides the genetic instructions for the spike protein of Sars-CoV-2. More specifically, it contained the two spike assembly instructions: one for the original Sars-CoV-2 variant and one for the Omicron variant BA.4/5. Once these protein building instructions enter the body, they are processed by the same cellular machinery that translates our own messenger RNA into proteins such as hormones, antibodies and enzymes. The resulting spike copies trigger an immune response and ensure that the body’s defenses remember and fight the germs when they come into contact with the real Sars-CoV-2 viruses.
Advantages of self-amplifying vaccines
But what’s special about the new vaccine is that it also tells the body how to make more of the spike RNA, so the body takes longer to make the protein. Researchers call such mRNA self-amplifying, that is, self-amplifying (saRNA). The vaccine also contained instructions for an enzyme called a replicase, which works like a photocopy.
The thought of a vaccine that copies itself in the body may sound worrying. However, complete viruses cannot be created this way. In addition, saRNA, like mRNA, is still broken down relatively quickly by the body. Although it lasts a little longer than mRNA, it does not reproduce indefinitely.
Self-amplifying RNA vaccines are expected to offer important advantages over traditional mRNA vaccines. Since saRNA vaccines have a built-in photocopier, so to speak, the vaccination dose can be much lower than before. This could reduce the side effects. Second, saRNA vaccines can produce a more durable immune response because the RNA remains in the body longer. While mRNA lasts a day or two until it is broken down by the body, self-replicating RNA can last for a month.
Comparison between Comirnaty and new RNA vaccine
Japan approved the new vaccine, called LUNAR-COV19, at the end of November based on study results involving 16,000 people from Vietnam. In the meantime, Arcturus researchers have also published the results of a direct comparison between LUNAR-COV19 and Comirnaty (the vaccine from Biontech/Pfizer) in the specialist journal “Lancet”. published. In this study of 800 people, vaccinated participants received either five micrograms of LUNAR-COV19 or 30 micrograms of Comirnaty as a fourth booster dose. The dose of saRNA was just one sixth of the mRNA dose.
Reactions to both vaccinations were usually mild and resolved quickly. However, the self-amplifying saRNA vaccine triggered the production of antibodies in a larger percentage of test subjects than Comirnaty. In addition, antibody levels against the Omicron variant BA.4/5 were higher a month later in people who received LUNAR-COV19. This could be a sign of the slightly longer shelf life. At the beginning of February, the Lancet authors finally presented the new data on immune responses.
The two developer companies Arcturus Therapeutic and CSL have already submitted an application for approval in Europe. They are also working on self-amplifying mRNA vaccines for seasonal flu and the less common but more severe pandemic flu with far more infected people. Other companies are exploring the possibility of using self-amplifying mRNA in rare genetic diseases to ensure the production of missing, vital proteins.
(jl)
To home page