Pseudohyphal Regulation by the Transcription Factor Rfg1p in Candida albicans
ABSTRACT The opportunistic human fungal pathogen Candida albicans is a major cause of nosocomial infections. One of the fundamental features of C. albicans pathogenesis is the yeast-to-hypha transition. Hypha formation is controlled positively by transcription factors such as Efg1p and Cph1p, which are required for hyphal growth, and negatively by Tup1p, Rfg1p, and Nrg1p. Previous work by our group has shown that modulating NRG1 gene expression, hence altering morphology, is intimately linked to the capacity of C. albicans to cause disease. To further dissect these virulence mechanisms, we employed the same strategy to analyze the role of Rfg1p in filamentation and virulence. Studies using …
Candida albicans adhesin Als3p is dispensable for virulence in the mouse model of disseminated candidiasis
The presence of specific proteins, including Ece1p, Hwp1p and Als3p, distinguishes theCandida albicanshyphal cell wall from that of yeast-form cells. These proteins are thought to be important for the ability ofC. albicanscells to adhere to living and non-living surfaces and for the cell-to-cell adhesion necessary for biofilm formation, and also to be pivotal in mediatingC. albicansinteractions with endothelial cells. Using anin vitroflow adhesion assay, we previously observed that yeast cells bind in greater numbers to human microvascular endothelial cells than do hyphal or pseudohyphal cells. This is consistent with previous observations that, in a murine model of disseminated candidiasis…
Human toll-like receptor 4 mutations are associated with susceptibility to invasive meningococcal disease in infancy.
Toll-like receptor 4 (TLR4) is required for efficient recognition of bacterial infections. We investigated an association between 2 TLR4 mutations (Asp 299 Gly and Thr 399 Ile) and meningococcal disease in 197 patients and 214 healthy controls by allele-specific real time polymerase chain reaction and direct sequencing. Although the allele frequency was not higher in the overall patient population, a significantly higher frequency in the 40 patients younger than 12 months of age (P = 0.007) was observed. We conclude that TLR4 mutations represent a risk factor for meningococcal disease in this age group.
Age-Dependent Association of Human Mannose-Binding Lectin Mutations With Susceptibility to Invasive Meningococcal Disease in Childhood
Mannose-binding lectin (MBL) is an important factor of the innate immune system, and MBL-initiated complement activation is an important early defense mechanism against various bacterial infections, including invasive meningococcal disease.In a pediatric cohort (ages 2-215 months) with invasive meningococcal disease, we investigated the overall and age-stratified frequency of 3 MBL exon 1 variations (C154T, G161A, G170A), previously shown to result in markedly decreased MBL plasma concentrations, by allele specific fluorescent hybridization probe real-time PCR assays and direct sequencing. Healthy age-matched volunteers with the same ethnic background and no history of meningococcal disease…