Immunoproteomic Analysis Reveals Novel Candidate Antigens for the Diagnosis of Paracoccidioidomycosis Due to Paracoccidioides lutzii

Abstract

Paracoccidioidomycosis (PCM) is a life-threatening systemic infection caused by the fungal pathogen Paracoccidioides brasiliensis and related species. Whole-genome sequencing and stage-specific proteomic analysis of Paracoccidioides offer the opportunity to profile humoral immune responses against P. lutzii and P. brasiliensis s. str. infection using innovative screening approaches. Here, an immunoproteomic approach was used to identify PCM-associated antigens that elicit immune responses by combining 2-D electrophoresis of P. lutzii and P. brasiliensis proteomes, immunological detection using a gold-standard serum, and mass spectrometry analysis. A total of 16 and 25 highly immunoreactive proteins were identified in P. lutzii and P. brasiliensis, respectively, and 29 were shown to be the novel antigens for Paracoccidioides species, including seven uncharacterized proteins. Among the panel of proteins identified, most are involved in metabolic pathways, carbon metabolism, and biosynthesis of secondary metabolites in both immunoproteomes. Remarkably, six isoforms of the surface-associated enolase in the range of 54 kDa were identified as the major antigens in human PCM due to P. lutzii. These novel immunoproteomes of Paracoccidioides will be employed to develop a sensitive and affordable point-of-care diagnostic assay and an effective vaccine to identify infected hosts and prevent infection and development of human PCM. These findings provide a unique opportunity for the refinement of diagnostic tools of this important neglected systemic mycosis, which is usually associated with poverty.

Prospecting Biomarkers for Diagnostic and Therapeutic Approaches in Pythiosis

“…This enzyme was highlighted in a recent study as an antigen in human paracoccidioidomycosis due to P. brasiliensis s. str. and P. lutzii [75]. Moreover, proteomic data show that P. lutzii fructose-1,6-bisphosphate aldolase interacts with macrophage proteins.…”

“…The 14-3-3 epsilon plays important roles in the cell cycle, coordinating cell progression and acting on signal transformation networks through bonds with other proteins [97,99]; these bonds affect the conformation and function of target proteins [98]. In Paracoccidioides brasiliensis, the 14-3-3 protein (Pb14-3-3) is a critical antigen [75], which is highly expressed in virulent isolates and works as an adhesin [100]. The downregulation of Pb14-3-3 leads to morphological modifications, such as more elongated cells, an impairment in dimor-phism, decreased interaction with pneumocytes, and reduced bud number [101].…”

Identification of Potentially Therapeutic Immunogenic Peptides From Paracoccidioides lutzii Species

“…Hence, we sought to identify immunostimulatory peptides in PL that could be developed as therapeutics. During the performance of this project, we use bioinformatic and immunoproteomic tolls, they are potentially useful tool to identify disease-associated antigens that can be used to elicit the immune responses or in the diagnostic, both methodologies has been currently used in the paracoccidioimycosis context and they are presenting promisor results (28,37).…”

“…Since, P10 has proven to be a promising therapeutic to combat PB PCM, we sought to identify peptides in PL that could similarly be applied for treatment (27,28). To accomplish this, we used an immunoproteomic approach, which is a powerful tool for identification and characterization of molecules with potential to serve as biomarkers for diagnoses (29)(30)(31)(32)(33).…”

Diagnosis of Pulmonary Infections Due to Endemic Fungi

“…DID, IB, ELISA, and LA most commonly detect antibodies to the gp43 antigen which is specific for P. brasiliensis complex, thus, they do not detect P. lutzii infection or some P. brasiliensis strains where the gp43 antigen is not expressed [ 54 , 56 , 107 , 109 ]. Antigen, PCR, and MALDI-TOF MS testing are not currently available outside research settings but may hold promise in the future [ 52 , 57 , 58 , 107 , 110 , 111 ].…”