Clinical, mycological and pathological findings in turkeys experimentally infected by Aspergillus fumigatus.

Experimental aspergillosis was induced in 1-day-old turkeys by intra-air-sac inoculation of a spore suspension of a 3-day-old Aspergillus fumigatus culture (CBS 144.89) containing 10(7) spores. Ten additional poults were used as controls. Infected and non-infected animals were closely observed at least twice a day for the appearance of clinical signs and were sequentially sacrificed at days 1, 2, 3, 5 and 7 post-inoculation. In the infected group, most lung tissues and air sac swabs were culture positive from day 1 to day 5. At 1 day post-inoculation, air sac membranes were multifocally and moderately to severely thickened by an oedema and covered by an exudate. A small number of germinating conidia were present in the superficial exudate, already giving rise to small radiating hyphae. Lung lesions were mild, dominated by a diffuse congestion and a mild heterophilic infiltration. From 2 to 3 days post-inoculation, air sac membranes were more severely affected and several granulomas were observed. Both granulomas and exudates were rich in germinated conidia and hyphae. Pulmonary lesions consisted in a diffuse pneumonia. Five days post-inoculation, air sac membrane lesions progressed to a severe, multifocal, heterophilic and granulomatous inflammation. Seven days post-inoculation, a reduction of the severity of the diffuse pneumonia was detected. Concomitantly, the fungal elements were mainly observed as fragmented tubules in the cytoplasm of multinucleate giant cells. The present study demonstrated that healthy turkey poults might be able to withstand exposure to 10(7) A. fumigatus spores.

Aspergillus fumigatus conidia inhibit tumour necrosis factor- or staurosporine-induced apoptosis in epithelial cells.

A major innate immune response to inhaled conidia of the opportunistic pathogen Aspergillus fumigatus (Af) is the synthesis of pro-inflammatory cytokines, which include tumour necrosis factor (TNF)-alpha, a known inducer of apoptosis. Modulation of host cell apoptosis has been reported to be one of the mechanisms whereby pathogens overcome host cell defences. Our study was designed to investigate whether or not Af conidia could modulate apoptosis induced by TNF-alpha or staurosporine (STS). Exposure of epithelial cells treated by these inducers and exposed to Af conidia decreased the number of apoptotic cells detected by Annexin V staining, analysis of nuclear morphology, terminal deoxynucleotidyl transferase-mediated fluorescein-dUTP nick end-labelling reaction and immunoblotting. Inhibition of apoptosis by Af conidia was seen in cells of the A549 pneumocyte II line, human tracheal epithelial 16HBE and primary human respiratory cells. Inhibition of apoptosis by Af conidia was also observed when apoptosis was induced by co-cultivating A549 cells with activated human alveolar macrophages. Unlike Af conidia, conidia of Cladosporium cladosporioides as well as latex beads or killed Af conidia have no inhibitory effect on TNF-alpha or STS-induced apoptosis. For TNF-induced apoptosis, the observed anti-apoptotic effect of Af conidia was found to be associated with a significant reduction of caspase-3.

Differentiation between isolates of Aspergillus fumigatus from breeding turkeys and their environment by genotyping with microsatellite markers.

To elucidate the epidemiology of the different forms of avian aspergillosis, 114 Aspergillus fumigatus isolates from sacrificed turkeys and 134 A. fumigatus isolates from air samples were collected and genotyped by microsatellite polymorphism marker analysis. Air sampling confirmed the huge diversity of A. fumigatus populations. Whereas older animals harbored several combinations of genotypes, 1-day-old chicks carried a unique genotype, suggesting a unique source of contamination.