Commending 20 Years Since the Formal Discovery of Immune Priming: The Innate Immune Memory

Immune memory provides a significant advantage in effectively eliminating species- or strain-specific infective agents upon subsequent encounters. While it was initially believed that immune memory was exclusive to vertebrates, it has now been clearly demonstrated in the last two decades that invertebrates and plants also possess innate immune memory (known as immune priming in invertebrates and plants to differentiate it from the adaptive memory in vertebrates). Although the existence of immune memory in non vertebrate organisms was initially debated for a decade, accumulating evidence over the last ten years has increasingly supported its presence in both animals and plants. This growing body of evidence has enabled researchers to understand better how immune memory evolves, the role of ecological factors that influence its outcome, the mechanisms beyond T or B cells that favor it, why insect plagues can resist their biological control agents from one generation to another, and the potential development of "vaccines" for invertebrates and plants.

A problem to be solved is to avoid confounding the immune priming as a form of immune memory with immune training, which is a non-specific response. Therefore, this Research Topic invites especially (but not only) studies that address specificity, e.g., incorporating homologous (similar) and heterologous (different) challenges in their experimental design.

In this Research Topic we aim to present the latest frontiers of research on immune priming (innate memory) in vertebrates, invertebrates, and plants, and welcomes both basic and applied information. We welcome the submission of Original Research, Reviews, Mini-Reviews and Opinions. This Research Topic delves into various aspects of immune priming, covering the following topics:

- Immune priming within or across generations.
- Mechanisms, evolution, and ecology of immune priming.
- The contribution of microbiota to immune priming.
- Theoretical and modelling approaches to immune priming.
- Studies that contradict the occurrence of immune priming.
- Application of the immune priming knowledge (i.e. development of vaccines).
- Novel ideas and methods to enhance the knowledge on immune priming.