Trained Immunity as a Prospective Tool against Emerging Respiratory Pathogens

Although parental vaccines offer long-term protection against homologous strains, they rely exclusively on adaptive immune memory to produce neutralizing antibodies that are ineffective against emerging viral variants. Growing evidence highlights the multifaceted functions of trained immunity to elicit a rapid and enhanced innate response against unrelated stimuli or pathogens to subsequent triggers. This review discusses the protective role of trained immunity against respiratory pathogens and the experimental models essential for evaluating novel inducers of trained immunity. The review further elaborates on the potential of trained immunity to leverage protection against pathogens via the molecular patterns of antigens by pathogen recognition receptors (PPRs) on innate immune cells. The review also focuses on integrating trained innate memory with adaptive memory to shape next-generation vaccines by coupling each one’s unique characteristics.