Aspergillus fumigatus is an etiological agent of invasive aspergillosis, a nosocomial infection that yields a mortality rate of up to 90 percent if undetected in early onset. Immunocompromised patients are at risk of A. fumigatus colonization following respiratory exposure. To date, methods to identify patients with invasive aspergillosis have been limited to unstandardized viable, non viable or cross-reactive serological tests. Species-specific biomarkers of exposure, such as hyphal exoantigens that are secreted during colonization, are not currently available in diagnostic assays.
Methods and Results:
Two Aspergillus collagen-like genes, arbitrarily designated as aclF1 and aclF2, were identified by a bioinformatic search in A. fumigatus genome. We hypothesized that these acl genes, presumably encoding the collagen-like proteins are widely distributed among A. fumigatus strains and species-specific for potential use as biomarkers. Genomic DNA was extracted from a collection of fungi representing a broad spectrum of Aspergillus species, including 12 strains of A. fumigatus and 17 control strains of other Aspergillus sp. The acl genes were sequenced in all 12 A. fumigatus strains to assess sequence polymorphism. Three primer pairs were designed for PCR amplification of the conserved 5’ and 3’ terminal regions, as well as primers flanking the central variable collagen-like region of aclF1. Similarly, two primer pairs were designed for the aclF2 gene. Both the 5’ and the 3’ probes yielded DNA bands of the predicted size in all A. fumigatus samples, but not in the control samples, while the aclF2-based primers yielded an amplicon in only one strain.
This pilot study suggests that aclF1 gene maybe a candidate biomarker for species-specific detection of A. fumigatus infections in humans.
Full conference title:
- ASM 111th (2011)