Journal of Vaccine Research 2024, Vol.14, No.2, 40-53 http://medscipublisher.com/index.php/jvr 45 4 Strategies for Universal Vaccine Development 4.1 Viral vector-based vaccines Viral vector-based vaccines utilize modified viruses to deliver genetic material encoding influenza antigens to host cells, thereby inducing an immune response. One promising approach involves the use of recombinant adenoviruses (rAd) expressing conserved influenza antigens such as nucleoprotein (NP) and matrix 2 (M2). Studies have shown that a single intranasal dose of rAd expressing these antigens can induce long-lasting immune responses, with antibody and T-cell responses persisting for over a year without the need for boosting. This approach has demonstrated broad protection against both group 1 and 2 influenza A viruses, as well as influenza B viruses, in animal models (Lo et al., 2021). Another study combined chimeric hemagglutinin constructs with viral vectors expressing NP and matrix protein 1 (M1), resulting in enhanced protection against diverse influenza strains, including H3N2, H10N8, by inducing robust antibody and T-cell responses (Figure 2) (Arunkumar et al., 2019). Figure 2 Evaluation of the protective efficacy of viral vector vaccines against H3N2 and H10N8 virus challenges (Adapted from Arunkumar et al., 2019) Image Caption: (A) shows the prime, boost, and second boost vaccination regimen for mice administered with viral vector vaccines, with doses given four weeks apart; (B) and (C) display the weight changes and survival rates of mice following challenges with H3N2 and H10N8 viruses, respectively. The vaccination groups include vaccines containing HA antigen, NP+M1 vaccine, early and late combined vaccine groups, and a control group. The experiments measured weight changes and 14-day survival rates post-infection for each group of mice (Adapted from Arunkumar et al., 2019) Additionally, the use of viral vectors such as Chimpanzee Adenovirus Oxford 1 and Modified Vaccinia Ankara virus has been explored. These vectors express conserved internal influenza virus antigens, aiming to induce
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