TLR7 and 9 agonists are highly effective mucosal adjuvants for norovirus virus-like particle vaccines

Abstract

Virus-like particles (VLPs) are an active area of vaccine research, development and commercialization. Mucosal administration of VLPs provides an attractive avenue for delivery of vaccines with the potential to produce robust immune responses. Nasal and oral delivery routes are particularly intriguing due to differential activation of mucosa-associated lymphoid tissues. We compared both intranasal and oral administration of VLPs with a panel of toll-like receptor (TLR) agonists (TLR3, 5, 7, 7/8, and 9) to determine the mucosal adjuvant activity of these immunomodulators. We selected Norwalk virus (NV) VLPs because it is an effective model antigen and an active area of research and commercialization. To prioritize these adjuvants, VLP-specific antibody production in serum (IgG, IgG1, IgG2a), vaginal lavages (IgG, IgA), and fecal pellets (IgA) were measured across a longitudinal timeseries in vaccinated mice. Additional distal mucosal sites (nasal, brochoalveolar, salivary, and gastrointestinal) were evaluated for VLP-specific responses (IgA). Intranasal co-delivery of VLPs with TLR7 or TLR9 agonists produced the most robust and broad-spectrum immune responses, systemically and at distal mucosal sites inducing VLP-specific antibodies at all sites evaluated. In addition, these VLP-specific antibodies blocked binding of NV VLPs to histo-blood group antigen (H type 1), supporting their functionality. Oral administration and/or other TLR agonists tested in the panel did not consistently enhance VLP-specific immune responses. This study demonstrates that intranasal co-delivery of VLPs with TLR7 or TLR9 agonists provides dose-sparing advantages for induction of specific and functional antibody responses against VLPs (i.e., non-replicating antigens) in the respiratory, gastrointestinal, and reproductive tract.

Keywords: :

• nasal vaccination
• oral vaccination
• TLR agonists
• mucosal adjuvants
• norovirus
• virus-like particles
• mucosal immunology
• antibody production

10.4161/hv.27147

Disclosure of Potential Conflicts of Interest

No potential conflicts of interest were disclosed.

Acknowledgments

This work was supported in part by NIH grant 1 U19 AI062150-01. We would like to thank Dynavax for providing us with the CpG-ISS 1018. We are greatly appreciative to Drs Hugh Mason and Charles Arntzen for their support, and for providing us with the vector and reagents used to generate the plant-derived NV VLPs. Lastly, we are thankful to Daaimah LaVigne for her assistance during the animal procedures and sample processing.