Abstract
Although vaccine delivery through the oral route remains the most convenient and safest way for mass immunization purposes, this method is limited by the requirement for large antigen doses and low vaccine efficacy. In this study, we generated recombinant baculoviruses (rBVs) expressing influenza hemagglutinin (A/PR/8/34) and orally delivered a low dose of rBVs to evaluate its vaccine efficacy in mice. Intranasal rBV vaccination was included in the whole experiment for comparison. We found that oral vaccination elicited high levels of virus-specific IgG and IgA antibody responses in both serum and mucosal samples (lung, tracheal, intestinal, fecal and vaginal). Surprisingly, complete protection from the lethal influenza challenge was observed, as indicated by reductions in the virus titer, inflammatory cytokine production, body weight change, and enhanced survival. These results suggest that oral delivery of the influenza rBV vaccine induces mucosal and systemic immunity, which protect mice from the lethal influenza virus challenge. Oral delivery of baculovirus vaccines can be developed as an effective vaccination route.
Highlights
Influenza is one of the most prevalent vaccine-preventable diseases
In comparison to the Intranasal route (IN)-immunized mice, no significant differences in IgG, IgA, and IgG1 titers were observed after boost immunization (Fig 2A–2C)
Oral route is an effective route for baculovirus vaccine administration that induces humoral immunity at the systemic and mucosal immunity which ensures rapid recovery and protection against lethal H1N1 influenza virus infection
Summary
Influenza is one of the most prevalent vaccine-preventable diseases. Every year, it causes an estimated 3 million cases of illness and from 250,000 to 500,000 deaths throughout the world. Oral delivery of vaccines is the most convenient and safe way of vaccination which could raise immunization coverage [1]. The Centers for Disease Control and Prevention has recommended several oral vaccines that are safe, immunogenic, and tolerogenic against cholera [2, 3]. Oral vaccination can induce mucosal immunity which might induce protection against influenza infection at the port of entry [1]. Mucosal route-delivered vaccine has been shown to induce higher protection compared to the intramuscular route of administration [9,10,11].
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