The fungal secretome and virulence: analysis of the proteins secreted by Cryptococcus gattii strains with different virulence profiles

L. T. Campbell, A. R. Simonin, Matthew P. Padula, Elizabeth Harry, B. R. Herbert, D. A. Carter

    Research output: Contribution to journalMeeting abstract


    Cryptococcus gattii is an environmental yeast-like fungus capable of
    causing disease in a wide range of animal hosts. In humans, disease
    progression begins after inhalation of the infectious propagule leading
    to infection of the lung. The infective yeast cells can then disseminate
    to the central nervous system, resulting in meningoencephalitis, which
    can be fatal if left untreated.
    Closely related strains of C. gattii exhibit significantly different
    degrees of virulence in the mammalian host. As fungi utilize absorbtive
    nutrition producing a range of secreted degrative enzymes, and as
    these may invoke a host response, the fungal secretome is likely to be
    very important in modulating host-pathogen interactions.
    We compared the secretomes of two C. gattii strains, one categorized
    as hypervirulent and the other exhibiting low-level virulence. C. gattii
    was grown under conditions designed to be as similar as possible to
    those encountered in vivo. Secreted proteins were captured from the
    culture supernatant and concentrated protein was analysed via 1D
    The two strains exhibited significantly different secreted proteins. A
    total of 27 proteins were identified with only four protein identifications
    being shared by both strains. The secretome of the hypervirulent strain,
    R265, primarily included uncharacterized proteins. However, bioinformatic
    analysis suggested these proteins contained catalytic regions with
    roles in carbohydrate degradation. The less virulent R272 strain secreted
    a more diverse set of proteins including enolase and transaldolase,
    enzymes which are canonically involved in glycolysis and the pentose
    phosphate pathway respectively. Interestingly however, these proteins
    are also both described fungal allergens that bind IgE.
    This study has found that closely related strains of C. gattii
    exhibiting different levels of virulence secrete very different cohorts of
    proteins. The proportionally greater number of proteins with a putative
    role in nutrient scavenging in the hypervirulent strain could suggest
    this strain has a greater capacity to source nutrients from a range of
    available substrates and hence more readily expand in new ecological
    niches. The greater number of potentially allergenic proteins in the
    strain exhibiting low-level virulence could indicate this strain triggers a
    more effective immune response in the mammalian host leading to
    clearance of the pathogen.
    Original languageEnglish
    Article numberP222
    Pages (from-to)163-163
    Number of pages1
    Issue numberS4
    Publication statusPublished - Jun 2012
    Event18th Congress of the International Society for Human and Animal Mycology - Berlin, Germany
    Duration: 11 Jun 201215 Jun 2012


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