Pathogenicity of basidiospores of Filobasidiella neoformans var. neoformans

Sukroongreung, S; Kitiniyom, K.; Nilakul, C; Tantimavanich, Srisurang

doi:10.1111/j.1365-280x.1998.00181.x

Cited by 25 publications

(37 citation statements)

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“…Human infection is acquired by inhalation of infectious propagules such as desiccated yeast cells or maybe basidiospores from environment sources 21,35,44 . C. neoformans is a heterothallic basidiomycete that exists as two mating types, α and a, being determined by single locus MAT, with two alleles 24 .…”

Section: Introductionmentioning

confidence: 99%

Genotyping, serotyping and determination of mating-type of Cryptococcus neoformans clinical isolates from São Paulo State, Brazil

Matsumoto

Fusco‐Almeida

Baeza

et al. 2007

Rev. Inst. Med. trop. S. Paulo

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SUMMARYThe basidiomycetous yeast Cryptococcus neoformans is an important fungal pathogen mainly in immunocompromised patients. In this study, 47 clinical isolates of C. neoformans from regions of São Paulo State were studied serologically by using the Crypto Check Iatron RM 304-K kit, their genetic diversity was estimated by PCR-fingerprinting with a microsatellite-specific sequence (GACA) 4 , RAPD with primer 6 (Amersham Pharmacia Biotech), PCR-restriction fragment length polymorphism (RFLP) analysis of the phospholipase B gene (PLB1) digested with AvaI and mating type analysis by PCR. All 47 strains isolated from HIV positive patients included in this study were serotype A and MATα. The majority of the isolates (45/47) were VNI and only two were VNII by PCR-fingerprinting and PCR-RFLP analysis. High degree of homogeneity was observed when (GACA) 4 was used, being highly correlated (> 0.9). In contrast, the RAPD analysis was more heterogeneous with higher number of molecular profiles. By PCR-RFLP, no new molecular type was found, enhancing the suggestion that the differences based on conserved gene as PLB1, can be resultant of ongoing divergent evolution within the C. neoformans complex, into the current eight subtypes. Our results furnish new information on the molecular epidemiology of C. neoformans in the southeast region of Brazil.

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Section: Introductionmentioning

confidence: 99%

Genotyping, serotyping and determination of mating-type of Cryptococcus neoformans clinical isolates from São Paulo State, Brazil

Matsumoto

Fusco‐Almeida

Baeza

et al. 2007

Rev. Inst. Med. trop. S. Paulo

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“…C. neoformans var. neoformans serotype D spores have been reported to be up to 100 times more infectious than yeast cells in an immunocompromised murine inhalation model (50). Studies to purify spores and analyze their pathogenicity in animal models using different infection methods were previously reported, documenting that spores can serve as infectious propagules under certain conditions, including when directly inoculated intracerebrally, intravenously, or by inhalation (7,50,59).…”

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Spores as Infectious Propagules ofCryptococcus neoformans

Velagapudi¹,

Hsueh²,

et al. 2009

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Cryptococcus neoformans and Cryptococcus gattii are closely related pathogenic fungi that cause pneumonia and meningitis in both immunocompromised and immunocompetent hosts and are a significant global infectious disease risk. Both species are found in the environment and are acquired via inhalation, leading to an initial pulmonary infection. The infectious propagule is unknown but is hypothesized to be small desiccated yeast cells or spores produced by sexual reproduction (opposite-or same-sex mating). Here we characterize the morphology, germination properties, and virulence of spores. A comparative morphological analysis of hyphae and spores produced by opposite-sex mating, same-sex mating, and self-fertile diploid strains was conducted by scanning electron microscopy, yielding insight into hyphal/basidial morphology and spore size, structure, and surface properties. Spores isolated by microdissection were found to readily germinate even on water agarose medium. Thus, nutritional signals do not appear to be required to stimulate spore germination, and as-yet-unknown environmental factors may normally constrain germination in nature. As few as 500 CFU of a spore-enriched infectious inoculum (ϳ95% spores) of serotype A C. neoformans var. grubii were fully virulent (100% lethal infection) in both a murine inhalation virulence model and the invertebrate model host Galleria mellonella. In contrast to a previous report on C. neoformans var. neoformans, spores of C. neoformans var. grubii were not more infectious than yeast cells. Molecular analysis of isolates recovered from tissues of infected mice (lung, spleen, and brain) provides evidence for infection and dissemination by recombinant spore products. These studies provide a detailed morphological and physiological analysis of the spore and document that spores can serve as infectious propagules.

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“…The spores that result from both traditional a-␣ mating and monokaryotic fruiting are the potential infectious agent of this organism (40,49). In addition, several genes within the 100-kb region of the mating type locus are linked to the virulence of this yeast (4,44).…”

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Amt2 Permease Is Required To Induce Ammonium-Responsive Invasive Growth and Mating in Cryptococcus neoformans

Rutherford¹,

Lin²,

Nielsen³

et al. 2008

Eukaryot Cell

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The conserved AmtB/Mep/Rh family of proteins mediate the transport of ammonium across cellular membranes in a wide range of organisms. Certain fungal members of this group are required to initiate filamentous growth. We have investigated the functions of two members of the AmtB/Mep/Rh family from the pathogenic basidiomycete Cryptococcus neoformans. Amt1 and Amt2 are low-and high-affinity ammonium permeases, respectively, and a mutant lacking both permeases is unable to grow under ammonium-limiting conditions. AMT2 is transcriptionally induced in response to nitrogen limitation, whereas AMT1 is constitutively expressed. Single and double amt mutants exhibit wild-type virulence in two models of cryptococcosis. Consistent with this, the formation of two C. neoformans virulence factors, cell wall melanin and the extracellular polysaccharide capsule, is not impaired in cells lacking either or both of the Amt1 and Amt2 permeases. Amt2 is, however, required for the initiation of invasive growth of haploid cells under low-nitrogen conditions and for the mating of wild-type cells under the same conditions. We propose that Amt2 may be a new fungal ammonium sensor and an element of the signaling cascades that govern the mating of C. neoformans in response to environmental nutritional cues.

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Pathogenicity of basidiospores of Filobasidiella neoformans var. neoformans

Cited by 25 publications

References 0 publications

Genotyping, serotyping and determination of mating-type of Cryptococcus neoformans clinical isolates from São Paulo State, Brazil

Genotyping, serotyping and determination of mating-type of Cryptococcus neoformans clinical isolates from São Paulo State, Brazil

Spores as Infectious Propagules ofCryptococcus neoformans

Amt2 Permease Is Required To Induce Ammonium-Responsive Invasive Growth and Mating in Cryptococcus neoformans

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