Single-shot Mesoporous Silica Rods Scaffold for Induction of Humoral Responses Against Small Antigens

Vaccines have shown significant promise in eliciting protective and therapeutic responses. However, most effective vaccines require several booster shots, and it is challenging to generate potent responses against small molecules and synthetic peptide antigens often used to increase target specificity and improve vaccine stability. As continuous antigen uptake and processing by APCs and persistent toll-like receptor (TLR) priming have been shown to amplify antigen specific humoral immunity, we explored whether a single injection of a mesoporous silica micro-rod (MSR) vaccine containing synthetic molecules and peptides can effectively generate potent and durable antigen-specific humoral immunity. A single injection of the MSR vaccine against a gonadotropin-releasing hormone (GnRH) decapeptide elicited highly potent anti-GnRH response that lasted for over 12 months. The MSR vaccine generated higher titers than bolus or alhydrogel alum vaccine formulations. Moreover, a MSR vaccine directed against a Her2/neu peptide within the Trastuzumab binding domain showed immunoreactivity to native Her2 protein on tumor cell surface and, when directed against nicotine, generated long-term anti-nicotine antibodies. Mechanistically, we found that the MSR vaccine induced persistent germinal center (GC) B-cell activity for more than 3 weeks after a single injection, generation of memory B cells, and that at least 7 days of immunostimulation by the vaccine was required to generate an effective humoral response. Together, these data suggest that the MSR vaccine represents a promising technology for synthetic antigen vaccines to bypass the need for multiple immunizations and enhance long-term production of antibodies against endogenous antigens in the context of reproductive biology, cancer, and chronic addiction.