Golnaz Sharafi
University of Tehran
Iran
Title: A comparative study of thermo-inducible HSP70 gene expression pattern in clinical and environmental isolates of Aspergillus fumigatus in a time-course manner
Biography
Biography: Golnaz Sharafi
Abstract
Introduction & Aim: Aspergillus fumigatus is the most frequent etiologic agent of invasive Aspergillosis in immunocompromised patients. Economic significance of Aspergillus spp., in animal health is mainly characterized by their ability in production of mycotoxins and cause disease in respiratory system of poultry. The ability of a pathogen to adapt to a high temperature environment such as that in the host body is the key factor for the pathogenesis. HSP70 family of genes and their related proteins play a pivotal role in resistance of microbial cells to stressed conditions within host body. Here, we examined relative gene expression of heat-inducible HSP70 gene in environmental and clinical (from infected ostriches) isolates of Aspergillus fumigatus.
Methods: The isolates were cultured at four temperature-points (20 °C, 30 °C, 37 °C and 42 °C) for five days, quantitative real-time PCR used to measure the relative gene expression of HSP70 gene in clinical isolates in comparison to Aspergillus fumigatus ATCC 90906 standard strain which was incubated at 25 °C for five days.
Results: During entire five days HSP70 expression level in clinical samples was higher than in environmental samples (p<0.05, Mann Whitney U test). Difference in expression level between two groups at 42 °C was reduced. Mean HSP70 expression level of five incubation days showed a slow and constantly increasing pattern by temperature elevation in both groups at 30 °C, 37 °C and 42 °C but in contrary at 20 °C both groups demonstrated a decreasing expression pattern. Temperature shift from 20 °C to 42 °C resulted in a strong HSP70 induction and up to 10 and 8.6 fold change in its expression levels at the end of fifth day of incubation in clinical and environmental groups, respectively.
Conclusion: We concluded that two temperature-points including 37 °C and 42 °C are major temperature-points inducing HSP70 expression in Aspergillus fumigatus and cause highest expression shift in both experimental groups.