Vaccines in shells

Vaccines currently used must be kept in the refrigerator during transportation and storage. Maintaining the so-called cold chain adds more than 80% to their cost. In addition, vaccines in liquid form have a short shelf life, in some cases only a few months. This creates some problems, especially in low-income countries and in remote areas where there is no electricity. Some vaccines also contain adjuvants – additional pharmacological or immunological substances to enhance the desired immune response, which may have side effects in the form of allergic reactions.

A group of researchers from the National Autonomous University of Mexico has developed a new technology for the production of vaccines that do not require refrigeration, with a multi-year shelf life. To do this, scientists have adapted the strategy used by baculoviruses – insect viruses harmless to humans, which allows them to be inactive and transmitted in the population from generation to generation until they are activated by any stressful factors for the host species. A key component of this strategy is the protein polyhedrin, which forms crystals around the virus, protecting it from the environment.

Previous studies by the authors have shown that the short sequence of the first 110 amino acids that make up polyhedrin (PH (1-110)) preserves the ability of the entire protein to form crystals, even when other proteins, including viral proteins, are attached to it.

It has been shown that the combination of a part of the circovirus, which can cause disease in pigs, with PH (1-110) stimulates the production of antibodies in vaccinated pigs. However, the exact characteristics of the particles that form after combining PH (1-110) and the virus, including thermal stability (ability to resist heating), have not been investigated, and none of them had sufficient strength for a possible immune response.

To investigate these characteristics and the possible benefit of PH (1-110) as a vaccine carrier, the researchers combined PH (1-110) with green fluorescent protein (GFP), which usually generates a weak immune response. As soon as PH (1-110) formed polyhedrin crystals around the protein, the authors injected mice with this PH (1-110) GFP complex to assess the immune response.

They found that mice treated with PH (1-110) GFP produced antibodies against GFP and demonstrated a powerful immune response similar to that of mice injected with GFP and an adjuvant. Since GFP alone does not cause a strong immune response, an adjuvant is usually needed. Antibodies against GFP remained in the blood of vaccinated mice for 24 weeks, which means that a long-term immunity was developed.

The researchers also found that GFP PH (1-110) particles stored as a dry powder at room temperature for 12 months still caused the production of antibodies in mice. The results show that PH (1-110) will help the production of thermostable vaccines that generate sufficient immune response without the need for adjuvant or cooling.

Since PH (1-110) can be paired with any protein, this technology will reduce the cost of preservation and delivery of vaccines by about 80%. Pharmaceutical companies will keep their profits, but consumers will pay less, this is especially important in low-income countries.

Article A.Cruz-Resendiz et al. A self-aggregating peptide: implications for the development of thermostable vaccine candidates is published in the journal BMC Biotechnology.

Aminat Adzhieva, portal "Eternal Youth" http://vechnayamolodost.ru based on BMC materials: New method to enable the production of cheaper, longer-lasting vaccines.