The extent of aspergillosis evolution depends particularly on the immune defence of the host. However, it has been suggested that the production of some molecules by A. fumigatus may play a role in pathogenicity. Nevertheless, it is not clear whether all environmental A. fumigatus strains have the same ability to induce infection. Our study by random amplified polymorphic DNA (RAPD) of A. fumigatiis strains from non-invasive, invasive aspergillosis and environment has suggested a relationship between a molecular marker and the ability of this pathoaen to invade tissues (1). In order to compare the virulence of different A. fumigatus strains independently to the immunological status of the host and the infection conditions, we have developed an animal model of invasive pulmonary aspergillosis (IPA). Swiss white female mice immunosuppressed with corticoid were inoculated intranasally with A.fumigatus conidia. Each isolate was typed by PCR with specific primers as positive or negative according to the amplification or not of a 0.95 kb fraament. The mortality curves reveal that strains had different virulence levels. A general correlation of the 0.95 kb positive strains was observed with ability to cause rapid IPA in mice with the environmental and clinical strains. These findings lend support to the hypothesis that certain isolates of A. fumigatus are more pathogenic than others and their virulence correlated with our molecular marker. We intend to screen a cDNA bank to know whether this fragment corresponds to a gene or is a untranslated sequence linked to growth ability.
Full conference title:
The 2nd Meeting of the European Confederation of Medical Mycology
- ECMM 2nd (1995)