Identification and characterization of an Aspergillus fumigatus “supermater” pair.

Sugui JA, Losada L, Wang W, Varga J, Ngamskulrungroj P, Abu-Asab M, Chang YC, O’Gorman CM, Wickes BL, Nierman WC, Dyer PS, Kwon-Chung KJ.

Citation

Sugui JA, Losada L, Wang W, Varga J, Ngamskulrungroj P, Abu-Asab M, Chang YC, O’Gorman CM, Wickes BL, Nierman WC, Dyer PS, Kwon-Chung KJ. (2011) Identification and characterization of an Aspergillus fumigatus “supermater” pair. mBio 2(6):

Abstract

The mating efficiency of 50 Aspergillus fumigatus isolates from both clinical and environmental sources was analyzed. Forty isolates completed the sexual cycle in 4 weeks with variable levels of fertility designated high, medium, or low. Two opposite-mating-type strains exhibiting the highest fertility, AFB62 (MAT1-1), isolated from a case of invasive aspergillosis, and AFIR928 (MAT1-2), isolated from the environment, were chosen as the supermater pair. Single cleistothecia obtained from a cross of the two strains harbored a minimum of 1 Ã? 10(4) ascospores. The viability of ascospores increased with the age of the fruiting body, 17% at 4 weeks and reaching 95% at 20 weeks. AFB62 and AFIR928 were equally virulent in two different murine models, despite differences in their sources. High recombination frequencies were observed when the closely linked genes alb1 (AFUA_2G17600) and abr2 (AFUA_2G17530) were used as genetic markers. Comparative genome hybridization analyses revealed that only 86 genes (ca. 0.86% of the genome) are significantly diverged between AFB62 and AFIR928. The high fertility in a relatively short period, combined with a high degree of virulence and a high recombination frequency, demonstrates that the mating pair AFB62 and AFIR928 provides an excellent tool for genetic studies of A. fumigatus. IMPORTANCE: Aspergillus fumigatus is a heterothallic fungal pathogen that causes life-threatening infections in immunocompromised hosts. Although heterothallism facilitates genetic study via recombinational analysis, previous work showed that a 6-month incubation period is required for the completion of sexual reproduction in this species. Such a long incubation period impedes progress in genetic research. To discover a highly fertile (supermater) pair that can complete the sexual cycle in a considerably shorter period, we screened 50 strains collected from various geographic regions for mating efficiency. We identified a highly virulent pair of supermaters that can be an invaluable tool for genetic study.