Infectious diseases are one of the major health issues worldwide, causing high morbidity, and mortality each year. Virus exposure, through infection or vaccination, can elicit cellular and humoral responses. For many viruses, these immune response are long-lasting; among cross-reactive pre-existing antibodies can exacerbate viral pathogenesis in some cases. The implication of pre-existing immunity to many pathogens ( viruses, bacteria, parasites, fungi, …) are not fully understood. Recently, several efforts have been focused on the potential of novel "omics" techniques to obtain information in a simple, faster, and more efficient way. Protein microarrays are one of these techniques useful for characterization of humoral response by multiplexed immunoassays with higy robustness and reproducibility.

Methods: a new multiplex platform has been designed and developed for the simultaneous immune-detection and s of IgM and IgG against 37 microbial antigens (Salmonella, SARS-CoV-2, flu, adenovirus, HPV, CMV,...) prevalent in the population that reflect each donor's infection history and previous immunity.

Results: In the case of the demographic variables such as sex, age range and ethnicity of the studied population, no distinctive profile was observed when comparing these characteristics. However, differences were observed in the distribution of antigens between the two immunoglobulin isotypes. The detection of IgM has been found to be predominant in the RBD protein and the nucleocapsid protein of SARS-CoV-2 and the outer membrane porin of Salmonella typhi[m1] . Humoral responses have been found to be highly heterogeneous between individuals to the same microbial antigens.

Conclusions: Knowing in depth the natural variations of these proteins, depending on the different clinical-biological characteristics, could enable us to correlate these patterns with patients presenting different pathologies, the role of pre-existing immunity, cross reactive immune responses, and vaccine approaches that circumvent pre-existing immunity. In addition, it could reduce mortality or improve diagnosis and treatment progression in an individualized and personalized manner.