Application of immunoproteomics to leptospirosis: towards clinical diagnostics and vaccine discovery

Abstract

Each of the currently available methods for serodiagnosis of leptospirosis, including the microscopic agglutination test (MAT), has its own drawback(s) when used in clinical practice. A new diagnostic test is therefore required for an earlier and more accurate diagnosis of leptospirosis. We applied immunoproteomics to define potential immunogens from five serovars of Leptospira reference strains. A leptospiral whole cell lysate from each serovar was used as the antigen to react with IgG and IgM in the sera from four patients with a positive MAT. Sera from four nonleptospirosis patients with a negative MAT were pooled and used as the negative control. 2-D Western blot analysis showed that the degree of immunoreactivity corresponded with the MAT titers. No immunoreactive spots were detected when the pooled control sera were used. A total of 24 protein spots immunoreacted with IgM and/or IgG from patients with leptospirosis. These immunoreactive proteins were identified by MALDI-TOF MS and were classified into five groups, including flagellar proteins, chaperones/heat shock proteins, transport proteins, metabolic enzymes, and hypothetical proteins. More immunoreactive spots were detected with antihuman IgG in the sera of all patients and with all the serovars of leptospires used. Some of the identified proteins immunoreacted only with IgG, whereas the others were detectable with both IgM and IgG. Among the immunoreactive proteins identified, FlaB proteins (flagellin and flagellar core protein) have been shown to have a potential role in clinical diagnostics and vaccine development. These data underscore the significant impact of immunoproteomics in clinical applications.

Serological proteome analysis to identify systemic candidiasis patients in the intensive care unit: Analytical, diagnostic and prognostic validation of anti‐Candida enolase antibodies on quantitative clinical platforms

“…In recent years, serological proteome analysis (SERPA) has intriguingly proved to be a promising screening tool for the discovery of biomarker panels in patients with infectious diseases [14][15][16] (including SC [17][18][19][20][21]), cancers [22,23], autoimmune disorders [24][25][26] and allergies [27]. Unlike genomic and transcriptomic strategies, this proteomic approach has the potential to detect antigenicity associated with PTM, a relevant feature for the design of diagnostic tests [18].…”

Nonclassically Secreted Proteins as Possible Antigens for Vaccine Development: A Reverse Vaccinology Approach

“…The term Bmoonlighting protein^is now widely used to describe these proteins which sequences containing neither known sequence motifs for surface anchoring nor identified secretion signals but appear on the bacterial surface to take on additional activities. Interestingly, some of them have already been shown as highly immunogenic and even protective in mice in several disease models [9][10][11].…”

Characterisation of the Proteome of Leptospira interrogans Serovar Canicola as a Resource for the Identification of Common Serovar Immunogenic Proteins

“…A conserved proteome for the three serovars was subsequently determined (Appendix 3 in the Supplementary Material); 60 proteins were revealed to be conserved (Appendices 3–5 in the Supplementary Material), sixteen of which have been previously reported in the literature as immunogenic (Table 2) through immune studies in the hamster [20] and mice models [23] and immunoblotting with serum from infected humans [22] and mice [21]. Further work is required to determine if any of the identified conserved proteins could be used as viable targets for therapeutic drugs, antimicrobials, and/or vaccines; however this does suggest that proteomic comparison of serovars could also be used as an effective screening tool; further refinement of the conserved proteome presented herein is suggested as the proteomes of additional serovars are published.…”