Production, Detection and Cross-Reactivity of Anti-Polysaccharide Antibodies from Environmental Fungi

Rafael Andrade Menolli,Claudia Rejane Lima De Macedo Costa,Erica Fernanda Osaku,Thais Soprani Ayala,Rosiane G Mello Zibetti,Pablo Rodrigo Da Rosa

doi:10.4236/abb.2014.510095

Abstract

The diagnosis of Invasive Fungal Disease (IFD) is difficult because the sensitivity of conventional culture and cytology methods for the detection of Aspergillus is poor, and because serological methods exhibit cross-reactivity with environmental fungi. Fungal polysaccharides are of particular interest in the serologic diagnosis of IFD, especially galactomannan (GM) and glucan, which have been recognized as useful tools for the diagnosis of fungal infections. Further investigation into polysaccharide antibody cross-reactivity is important in improving diagnostic tests. Our aim was to verify the production of antibodies against fungal antigens in mice immunized with exopolysaccharides (EPS) obtained from three fungal species (Aspergillus terreus, Paecilomyces variotii and Curvularia brachyspora). ELISA assays were performed to evaluate homologous and heterologous reactions and showed anti-polysaccharide antibodies production. EPS from A. terreus was immunogenic enough to immunize the animal and lead to antibody production against this EPS. In addition, no cross-reactivity was observed with EPS obtained from P. variotii and C. brachyspora. The EPS from P. variotii did not exhibit good immunogenicity, whereas EPS from C. brachyspora showed good immunogenicity, and heterologous reactions were detected on the ELISA assays performed using the EPS from this species. The results indicate that immunization can occur for environmental fungal polysaccharides, generating antibodies may be interfere in serological diagnosis that are based on detection of fungal polysaccharides, mainly glucans and galactomannans.

Highlights

Diagnosis and prompt introduction of antifungal therapy is essential for good prognosis in patients with systemic fungal infections or invasive fungal disease (IFD) [1]
Invasive aspergillosis (IA) is one of the most prominent forms of IFD. This disease has been the cause of death for many individuals, with infections mainly occurring in hematopoietic stem cell transplant patients [3], in patients with certain hematologic disorders [4] and in individuals who receive organ transplants and especially lung transplants [5]
The standard EPS concentrations for A. terreus, P. variotii and C. brachyspora fungi were decided based on the absorbance measured in tests in which sera from immunized animals were challenged with different antigen concentrations

Summary

Introduction

Diagnosis and prompt introduction of antifungal therapy is essential for good prognosis in patients with systemic fungal infections or invasive fungal disease (IFD) [1]. Invasive aspergillosis (IA) is one of the most prominent forms of IFD. This disease has been the cause of death for many individuals, with infections mainly occurring in hematopoietic stem cell transplant patients [3], in patients with certain hematologic disorders [4] and in individuals who receive organ transplants and especially lung transplants [5]. The difficulty in performing early diagnosis is one of the reasons for the high mortality because the appearance and symptoms of IA are often not specific or are attenuated by medications such as corticosteroids. Detection of Aspergillus spp fungus in respiratory samples is highly indicative of IA, but the culture only turns positive at the later stages of the disease [6]

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Methods

Results