Dual Antigen COVID-19 Vaccine Could Provide Long-Term Protection

At present, the COVID-19 vaccines comprise of neutralizing antibodies that can combat Spike (S) protein present in the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). These antibodies are known to possess the property of hindering infection and also lowering the severity of the disease. However, the current concern is that the variants of the SARS-CoV-2 easily escape the vaccine-induced immune response and thus, there is a need for dynamic vaccines. Furthermore, the researchers have found vaccines including NVX-CoV2373, ChAdOx, and Ad26.COV2-S rendered low protection against the B.1.351 variant during the trials.

On detailed studying, the wild-type S-specific antibodies prompted by the BNT162b1 and mRNA-1273 vaccines showed less of binding to the S protein of the B.1.351 variants. It is thus clear that the monovalent vaccines targeting the S protein may not be effective in protecting against constantly emerging variants. Thus, the researchers have recently shifted their focus toward T cells to increase protection term against COVID-19. The vaccines mRNA1273 and BNT162b1 contain S-specific T cell responses which help it render protection against COVID-19. The researchers have recently developed a vaccine that provides long-term immunity against the different variants of SARS-CoV-2. The latest dual-antigen COVID-19' T cell' vaccine is developed with the help of next-generation human adenovirus serotype 5 (Ad5) platform depending on the activation of nucleocapsid (N) protein and S protein of SARS-CoV-2.

The vaccine development is found to contain complete S protein comprised of an SD1 receptor binding domain. The modification of the S1 and S2 domains helped alter the surface expression or S-Fusion. Also, the complete N protein was changed using an Enhanced T cell Stimulation Domain (ETSD) to transform N to the endo- or lysosomal compartment, thereby enhancing MHC class I and II expression. The researchers found the E1, E2b, and E3 gene regions to be skipped in the hAd5 platform. These omitted regions helped reduce host anti-vector (adenovirus) immune responses and promoted efficient antigen expression. This immune response helped activate T cell expression. The studies have shown results as well. The hAd5 S-Fusion + N-ETSD COVID-19 T cell vaccine is undergoing trials for knowing the best effective vaccine delivery method, whether intranasal, sublingual, or oral tablet. Its efficacy is already proved effective against diverse variants.