The role of the GPI-Protein PbPga1 from Paracoccidioides brasiliensis in the biology of the fungus and in the pathogen-host interaction.

• Grant number: 24/03335-8
• Support Opportunities: Regular Research Grants
• Start date: August 01, 2025
• End date: July 31, 2027
• Field of knowledge: Biological Sciences - Microbiology - Biology and Physiology of Microorganisms
• Principal Investigator: Paulo Sergio Rodrigues Coelho
• Grantee: Paulo Sergio Rodrigues Coelho
• Host Institution: Faculdade de Medicina de Ribeirão Preto (FMRP). Universidade de São Paulo (USP). Ribeirão Preto , SP, Brazil
• Associated researchers: CELIA MARIA DE ALMEIDA SOARES ; Fernando José dos Santos Rodrigues ; Relber Aguiar Gonçales ; Thiago Aparecido da Silva

Abstract

Paracoccidioidomycosis (PCM) is an endemic systemic fungal disease in Latin America caused by fungal species of the genus Paracoccidioides spp. Although this disease is considered one of the main systemic mycoses in Latin America, little is known about the pathogenesis of this fungus. Pga1 (Predicted GPI anchored protein one) is a cell wall matrix protein found in many fungi. In P. brasiliensis, the Pga1 protein is considered an important component of the cell wall and has been associated with the host immune response. However, the precise role of Pga1 in the biology and pathogenesis of PCM has not yet been fully elucidated. Therefore, the present research project aims to understand the role of Pga1 in the biology and pathogenesis of PCM. To achieve the general objective, three specific objectives have been defined. The first objective is to construct Pga1 mutant strains to understand the role of this protein in the fungus biology. For this purpose, RNA antisense technology (ATMT) and Agrobacterium tumefaciens-mediated transformation will be used. Subsequently, growth and dimorphic transition analyses will be carried out through growth curve analyses and light and fluorescence microscopy to determine the role of Pga1 in these processes. The second objective is to investigate the role of Pga1 in the fungal cell wall by evaluating its structure and modulation in the presence or absence of Pga1. Sensitivity tests to stressors and antifungal agents will be performed to determine the role of Pga1 in maintaining the cell wall. Additionally, confocal and electron microscopy will be used to assess the cell wall structure in the presence or absence of Pga1. The third objective is to evaluate the role of Pga1 in the virulence of the fungus through a virulence test using a murine infection model. In this model, colony-forming unit (CFU) counts, histology, and survival after infection will be evaluated. The phagocytic capacity of macrophages will also be assessed using mutant and wild-type strains. The results of these analyses will be crucial for understanding the role of Pga1 in the biology and pathogenesis of PCM, which may lead to the development of new therapeutic and diagnostic strategies. (AU)