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Cryptococcus gattii virulence composite: candidate genes revealed by microarray analysis of high and less virulent Vancouver island outbreak strains.

Ngamskulrungroj P, Price J, Sorrell T, Perfect JR, Meyer W - PLoS ONE (2011)

Bottom Line: In vitro phenotypic studies and transcription analysis confirmed the microarray results.Gene disruption of LAC1 and MPK1 revealed defects in melanin synthesis and cell wall integrity, respectively, where CAS3 was not essential for capsule production.Overall, this study provides the basis for further genetic studies to characterize the differences in the virulence composite of strains with minor evolutionary divergences in gene expression in the primary pathogen C. gattii, that have led to a major invasive fungal infection outbreak.

View Article: PubMed Central - PubMed

Affiliation: Molecular Mycology Research Laboratory, Centre for Infectious Diseases and Microbiology, Sydney Medical School-Westmead, Westmead Millennium Institute, Sydney Emerging Infections and Biosecurity Institute, The University of Sydney, Westmead Hospital, Westmead, New South Wales, Australia.

ABSTRACT
Human and animal cryptococcosis due to an unusual molecular type of Cryptococcus gattii (VGII) emerged recently on Vancouver Island, Canada. Unlike C. neoformans, C. gattii causes disease mainly in immunocompetent hosts, despite producing a similar suite of virulence determinants. To investigate a potential relationship between the regulation of expression of a virulence gene composite and virulence, we took advantage of two subtypes of VGII (a and b), one highly virulent (R265) and one less virulent (R272), that were identified from the Vancouver outbreak. By expression microarray analysis, 202 genes showed at least a 2-fold difference in expression with 108 being up- and 94 being down-regulated in strain R265 compared with strain R272. Specifically, expression levels of genes encoding putative virulence factors (e.g. LAC1, LAC2, CAS3 and MPK1) and genes encoding proteins involved in cell wall assembly, carbohydrate and lipid metabolism were increased in strain R265, whereas genes involved in the regulation of mitosis and ergosterol biosynthesis were suppressed. In vitro phenotypic studies and transcription analysis confirmed the microarray results. Gene disruption of LAC1 and MPK1 revealed defects in melanin synthesis and cell wall integrity, respectively, where CAS3 was not essential for capsule production. Moreover, MPK1 also controls melanin and capsule production and causes a severe attenuation of the virulence in a murine inhalational model. Overall, this study provides the basis for further genetic studies to characterize the differences in the virulence composite of strains with minor evolutionary divergences in gene expression in the primary pathogen C. gattii, that have led to a major invasive fungal infection outbreak.

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Related in: MedlinePlus

Capsule formation of strains R265 and R272.Yeast cells were grown in DME at 37°C with 5% CO2 and RPMI-1640 medium at 37°C with 5% CO2 for 72 h.
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pone-0016076-g002: Capsule formation of strains R265 and R272.Yeast cells were grown in DME at 37°C with 5% CO2 and RPMI-1640 medium at 37°C with 5% CO2 for 72 h.

Mentions: When cultured in three different capsule-inducing conditions, capsule size was larger in strain R265 than in strain R272. The average capsule to capsule: cell wall to cell wall ratios of strain R265 compared to strain R272 were 2.1 versus 1.8 in DME and 3.0 versus 2.1 in RPMI with CO2 (Figure 2). All results were statistically significant (p = 0.005 for DME and p<0.001 for RPMI).


Cryptococcus gattii virulence composite: candidate genes revealed by microarray analysis of high and less virulent Vancouver island outbreak strains.

Ngamskulrungroj P, Price J, Sorrell T, Perfect JR, Meyer W - PLoS ONE (2011)

Capsule formation of strains R265 and R272.Yeast cells were grown in DME at 37°C with 5% CO2 and RPMI-1640 medium at 37°C with 5% CO2 for 72 h.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3020960&req=5

pone-0016076-g002: Capsule formation of strains R265 and R272.Yeast cells were grown in DME at 37°C with 5% CO2 and RPMI-1640 medium at 37°C with 5% CO2 for 72 h.
Mentions: When cultured in three different capsule-inducing conditions, capsule size was larger in strain R265 than in strain R272. The average capsule to capsule: cell wall to cell wall ratios of strain R265 compared to strain R272 were 2.1 versus 1.8 in DME and 3.0 versus 2.1 in RPMI with CO2 (Figure 2). All results were statistically significant (p = 0.005 for DME and p<0.001 for RPMI).

Bottom Line: In vitro phenotypic studies and transcription analysis confirmed the microarray results.Gene disruption of LAC1 and MPK1 revealed defects in melanin synthesis and cell wall integrity, respectively, where CAS3 was not essential for capsule production.Overall, this study provides the basis for further genetic studies to characterize the differences in the virulence composite of strains with minor evolutionary divergences in gene expression in the primary pathogen C. gattii, that have led to a major invasive fungal infection outbreak.

View Article: PubMed Central - PubMed

Affiliation: Molecular Mycology Research Laboratory, Centre for Infectious Diseases and Microbiology, Sydney Medical School-Westmead, Westmead Millennium Institute, Sydney Emerging Infections and Biosecurity Institute, The University of Sydney, Westmead Hospital, Westmead, New South Wales, Australia.

ABSTRACT
Human and animal cryptococcosis due to an unusual molecular type of Cryptococcus gattii (VGII) emerged recently on Vancouver Island, Canada. Unlike C. neoformans, C. gattii causes disease mainly in immunocompetent hosts, despite producing a similar suite of virulence determinants. To investigate a potential relationship between the regulation of expression of a virulence gene composite and virulence, we took advantage of two subtypes of VGII (a and b), one highly virulent (R265) and one less virulent (R272), that were identified from the Vancouver outbreak. By expression microarray analysis, 202 genes showed at least a 2-fold difference in expression with 108 being up- and 94 being down-regulated in strain R265 compared with strain R272. Specifically, expression levels of genes encoding putative virulence factors (e.g. LAC1, LAC2, CAS3 and MPK1) and genes encoding proteins involved in cell wall assembly, carbohydrate and lipid metabolism were increased in strain R265, whereas genes involved in the regulation of mitosis and ergosterol biosynthesis were suppressed. In vitro phenotypic studies and transcription analysis confirmed the microarray results. Gene disruption of LAC1 and MPK1 revealed defects in melanin synthesis and cell wall integrity, respectively, where CAS3 was not essential for capsule production. Moreover, MPK1 also controls melanin and capsule production and causes a severe attenuation of the virulence in a murine inhalational model. Overall, this study provides the basis for further genetic studies to characterize the differences in the virulence composite of strains with minor evolutionary divergences in gene expression in the primary pathogen C. gattii, that have led to a major invasive fungal infection outbreak.

Show MeSH
Related in: MedlinePlus