Email updates

Keep up to date with the latest news and content from BMC Microbiology and BioMed Central.

Open Access Research article

Immunoproteomics based identification of thioredoxin reductase GliT and novel Aspergillus fumigatus antigens for serologic diagnosis of invasive aspergillosis

Li-ning Shi, Fang-qiu Li*, Mei Huang, Jing-fen Lu, Xiao-xiang Kong, Shi-qin Wang and Hai-feng Shao

Author Affiliations

Laboratory of Molecular Biology, Institute of Medical Laboratory Sciences, Jinling Hospital, School of Medicine, Nanjing University, 305 East Zhongshan Road, Nanjing 210002, PR China

For all author emails, please log on.

BMC Microbiology 2012, 12:11  doi:10.1186/1471-2180-12-11

Published: 18 January 2012

Abstract

Background

There has been a rising incidence of invasive aspergillosis (IA) in critically ill patients, even in the absence of an apparent predisposing immunodeficiency. The diagnosis of IA is difficult because clinical signs are not sensitive and specific, and serum galactomannan has relatively low sensitivity in this group of patients. Therefore, more prompt and accurate disease markers for early diagnosis are needed. To establish disease markers demands a thorough knowledge of fungal antigens which may be detected in the serum or other body fluids of patients. Herein we report novel immunodominant antigens identified from extracellular proteins of Aspergillus fumigatus.

Results

Extracellular proteins of A. fumigatus were separated by two-dimensional electrophoresis (2-DE) and probed with the sera from critically ill patients with proven IA. The immunoreactive protein spots were identified by MALDI-TOF mass spectrometry (MALDI-TOF -MS). Forty spots from 2DE gels were detected and 17 different proteins were identified as immunogenic in humans. Function annotation revealed that most of these proteins were metabolic enzymes involved in carbohydrate, fatty acid, amino acid, and energy metabolism. One of the proteins, thioredoxin reductase GliT (TR), which showed the best immunoactivity, was analyzed further for secretory signals, protein localization, and homology. The results indicated that TR is a secretory protein with a signal sequence exhibiting a high probability for secretion. Furthermore, TR did not match any human proteins, and had low homology with most other fungi. The recombinant TR was recognized by the sera of all proven IA patients with different underlying diseases in this study.

Conclusions

The immunoreactive proteins identified in this study may be helpful for the diagnosis of IA in critically ill patients. Our results indicate that TR and other immunodominant antigens have potential as biomarkers for the serologic diagnosis of invasive aspergillosis.