Preclinical evaluation demonstrates that sublingual canine influenza vaccination confers lung-sparing protection in mice and beagles, indicating a safe needle-free mucosal delivery strategy.
Safe mucosal delivery of live respiratory vaccines remains challenging. We developed CIV SA1 , an NS1-truncated H3N2 canine influenza live attenuated vaccine (LAIV), and evaluated sublingual administration as a non-respiratory mucosal route. In mice, high-dose sublingual CIV SA1 produced no recoverable infectious virus or histopathologic injury in lungs, whereas intranasal dosing produced pulmonary replication. A single sublingual dose induced serum IgG with hemagglutination-inhibition and neutralizing activity comparable to intranasal vaccination, enriched upper-airway IgA/IgG, and elicited IFN-γ cellular recall. Following lethal mouse-adapted CIV challenge, sublingual and intranasal LAIV preserved survival and markedly suppressed recoverable infectious virus in lungs and nasal washes. Following wild-type CIV challenge, sublingual LAIV also suppressed recoverable infectious virus in both compartments. CIV SA1 formulated as a gelatin-CMC orodispersible film preserved infectivity, released vaccine cargo rapidly in artificial saliva, was locally tolerated in beagles without detectable shedding, and induced systemic functional antibodies, upper-airway IgA/IgG, and peripheral IFN-γ cellular responses, supporting needle-free veterinary delivery.
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Hwang et al. (2026) studied this question.
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