The weekly online publication Capsid & Tail suggests considering bacteriophages as the basis for creating "vaccine cocktails" against COVID-19, providing long-term protection against various strains of the SARS-CoV-2 coronavirus.

Today, the world is developing and deploying vaccines against SARS-CoV-2, the coronavirus that causes COVID-19, at an unprecedented pace. Vaccines use various methods of delivering and presenting SARS-CoV-2 antigens to the body, ranging from traditional methods (weakened viral particles or individual viral proteins) to the latest ones (mRNA vaccines and vector vaccines, which enable the synthesis of the pathogenic virus's antigenic components by a person's own cells).

Vaccines containing whole viral components have demonstrated acceptable levels of protection in clinical trials, but their efficacy is expected to be lower than that of nucleic acid-based vaccines (RNA vaccines) and vector vaccines (in which the pathogenic virus genes are delivered to the body via safe viral vectors). This is explained by the fact that the former elicit a polyclonal immune response, while the latter elicit a more potent monoclonal response against the coronavirus surface antigen, the S protein.

Unfortunately, since the beginning of the pandemic , mutations have been repeatedly detected in the SARS-CoV-2 S protein , particularly in its protruding region, the receptor-binding domain (RBD). These mutations can accumulate and impact , sometimes critically, the effectiveness of existing vaccines. Given this, it seems advisable to create a "vaccine cocktail" containing the maximum variety of S protein RBD mutations.

Several COVID-19 vaccines are being developed using bacteriophages. Phages are used , in particular, to deliver DNA to cells in the nasopharyngeal mucosa and synthesize virus-like particles that are designed to trigger an immune response. Adaptive Phage Therapeutics announced that it has begun trials of a bacteriophage-based COVID-19 vaccine for oral and intranasal administration. However, these vaccines also appear to be targeted against a single virus variant, and mutations in the S protein RBD could render them ineffective. Phage display technology appears promising for addressing this issue.

Phage display technology makes it relatively easy to generate a complete library of SARS-CoV-2 S protein RBD variants (using the same principle used to generate antibody libraries ). This cocktail is capable of eliciting an immune response to all available S protein RBD variants. Another advantage of bacteriophages as vaccine components is that they are safe for the human body and act as natural adjuvants, enhancing immune responses. There is reason to believe that such "vaccine cocktails" can provide a long-term immune response to various SARS-CoV-2 S protein RBD variants, thereby preparing the body for encounters with various COVID-19 strains.