> We recently reported the development of a “universal” phage T4 vaccine design platform by Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) engineering that can rapidly generate multivalent vaccine candidates.
> Intriguingly, the T4-CoV-2 vaccine induced high levels of Spike-specific serum IgA antibodies (endpoint titers up to 62,500) when administered by either the i.m. [intramuscular] or the i.n. [intranasal] route. This is notable because IgA stimulation is not commonly observed in traditional vaccines…
> … significantly elevated percentages of CD4+ T cells producing IFN-γ were detected in the i.n. group (1%) in comparison to the i.m. group (0.55%) of vaccinated mice (P < 0.001 between i.n. and i.m.). These data indicated an enhanced Th1-mediated immunity induced by i.n. administration of the vaccine.
> … high titers of mucosal sIgA antibodies were elicited by i.n. vaccination (endpoint titers up to 12,500), in addition to high levels of systemic immune responses as described above. In contrast, i.m. immunization failed to produce sIgA, which is not unexpected.