RT–PCR analysis ofCandida albicansALS gene expression in a hyposalivatory rat model of oral candidiasis and in HIV-positive human patients

Abstract

ALS gene expression was studied in the hyposalivatory rat model of oral candidiasis and in clinical specimens collected from HIV-positive patients to assess similarities in expression patterns between the model system and clinical isolates. Two Candida albicans strains, SC5314 and OY-2-76, were used in the rat model system and infection progressed for 3 or 5 days. The strains produced similar oral lesions at 3 days. At 5 days, strain OY-2-76 produced more superficial lesions containing relatively more yeast forms compared to invasive hyphal forms observed for strain SC5314. For all infections, the most severe lesions were observed on the tongue and gingiva overlying the mandible. ALS transcripts were easier to detect by RT-PCR later in infection and under other conditions where more fungal cells were present. Expression of ALS1, ALS2, ALS3 and ALS4 was observed in rats infected for 3 days with ALS5 and ALS9 transcripts detected after 5 days of infection. Expression of ALS6 was observed in a single specimen from a 5-day infection while ALS7 transcript was never found. Expression of all ALS genes was observed in oral clinical material collected from HIV-positive patients although ALS6 and ALS7 transcripts required an extra PCR amplification step to be detected. Overall, the patterns of ALS gene expression were similar between the rat model and human clinical specimens, suggesting that the model would be useful for studying the phenotype of al delta/al delta mutant strains.

Property Differences among the Four Major Candida albicans Strain Clades

“…However, no associations were found between the various midrepeat alleles and strain virulence for mice. Since adherence and morphogenesis are phenomena mediated and regulated by many gene products (1,9,14,19,28,42), it is likely that C. albicans possesses considerable functional redundancy with respect to these properties, so while differences may arise between adhesin structures within different strain clades, these are unlikely to translate to detectable effects on strain virulence.…”

Host–pathogen interactions and virulence-associated genes during Candida albicans oral infections

“…1, and Wächtler et al, 2011;Zakikhany et al, 2007), such as adhesins, including members of the agglutinin-like sequence (Als) family and hyphal wall protein 1 (Hwp1). Genes encoding these adhesins were shown to be expressed in samples from patients suffering from oral candidiasis (Green et al, 2006;Naglik et al, 2006;Zakikhany et al, 2007). Adhesion via Hwp1 is due to an astonishing example of fungal adaptation to the host and can be described as molecular mimicry since the amino-terminal effector region of Hwp1 is recognized as a substrate for host transglutaminase activity, which is associated with the surface of oral epithelial cells.…”

“…Commonly used cell lines for monolayer infection experiments include TR146 and FaDu (Dalle et al, 2009;Park et al, 2009). Additionally, investigations using biopsy samples from patients suffering from oral candidiasis have been performed, providing valuable insight into the processes which actually occur during infections (Green et al, 2006;Naglik et al, 2005Naglik et al, , 2006Naglik et al, , 2008bSchaller et al, 1998;Zakikhany et al, 2007).…”

Recent mouse and rat methods for the study of experimental oral candidiasis

“…This condition has been used by various researchers to induce oral candidiasis in rat models 38 , 47 - 50 . Green et al 50 studied C. albicans ’ expression of ALS genes (encoding large cell-surface glycoproteins that function in the process of adhesion to host surfaces) in the hyposalivatory Sprague-Dawley rat model after surgical removal of the salivary glands.…”