Nasal Nanovaccines for SARS-CoV-2 to Address COVID-19

Abstract

COVID-19 is still prevalent around the globe. Although some SARS-CoV-2 vaccines have been distributed to the population, the shortcomings of vaccines and the continuous emergence of SARS-CoV-2 mutant virus strains are a cause for concern. Thus, it is vital to continue to improve vaccines and vaccine delivery methods. One option is nasal vaccination, which is more convenient than injections and does not require a syringe. Additionally, stronger mucosal immunity is produced under nasal vaccination. The easy accessibility of the intranasal route is more advantageous than injection in the context of the COVID-19 pandemic. Nanoparticles have been proven to be suitable delivery vehicles and adjuvants, and different NPs have different advantages. The shortcomings of the SARS-CoV-2 vaccine may be compensated by selecting or modifying different nanoparticles. It travels along the digestive tract to the intestine, where it is presented by GALT, tissue-resident immune cells, and gastrointestinal lymph nodes. Nasal nanovaccines are easy to use, safe, multifunctional, and can be distributed quickly, demonstrating strong prospects as a vaccination method for SARS-CoV-2, SARS-CoV-2 variants, or SARS-CoV-n.

Keywords: COVID-19; nanovaccine; nasal vaccination.

Figure 1

Different routes of vaccination produce different types of immunity at different sites. Oral vaccines along the digestive tract to the GALT, which produce mucosal and systemic immunity. Aerosol vaccines reach BALT by inhalation into the bronchi, which produce mucosal and systemic immunity. Nasal vaccines produce mucosal and systemic immunity at NALT.

Figure 2

Functional NPs in SARS-CoV-2 vaccines mainly include promoting cell uptake of antigens, protecting antigens, and fully mimicking pathogens. Part of the structure of SARS-CoV-2 was selected to be wrapped in a nanocapsule, or superfluous structures removed from SARS-CoV-2 were replaced with NPs.

Figure 3

(1) Dendritic cells (DC) pass through mucosal epithelial cells to capture NPs in the mucosal layer. (2) NPs can also passively permeate through epithelial junctions to access the underlying DC. (3) A pocket enriched in APC (macrophages-Mφ, DC, and lymphocytes T) created by the M cells, which perform the sampling of the luminal antigens so that the immune cells contact the NP/antigen. (4) NPs can also enter cells through endocytosis and deliver the antigens to cells.