**5. Conclusions**

VLPs have been exploited as a platform technology to develop vaccines for diverse targets, including specific antigens or epitopes derived from infectious disease targets, self-antigens involved in chronic diseases, and even small molecules, such as drugs of abuse [65]. In general, VLP display is regarded as a method for enhancing the magnitude of an antibody response, similar to how adjuvants can increase the immunogenicity of vaccines. However, as described in this article, and as summarized in Figure 3, the multivalent nature of VLPs also confers special immunostimulatory properties not

typically conferred by adjuvants, particularly the ability to elicit durable antibody responses through the induction of LLPCs. For many targets, the induction of long-lived antibody responses is likely to be a key factor in vaccine efficacy. A deeper understanding of the mechanisms whereby multivalent antigens can lead to the induction and maintenance of LLPCs will influence vaccine design and likely lead to improved vaccines in the future.

**Author Contributions:** B.C., writing—original draft preparation; D.S.P., writing—review and editing; all authors have read and agree to the published version of the manuscript. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by the US National Institutes of Health (NIH), grants number R01 HL131696 and U19 AI113187.

**Acknowledgments:** Thanks to Teal Clocksin, Ebenezer Tumban, and Julianne Peabody for generating the data shown in Figures 1 and 2.

**Conflicts of Interest:** BC and DSP have equity in Agilvax, Inc.
