Journal of medical and veterinary mycology : bi-monthly publication of the International Society for Human and Animal Mycology最新文献

Several investigators have developed monoclonal antibodies against the capsular polysaccharide of Cryptococcus neoformans which have potential therapeutic applications. Using a rat model of C. neoformans meningitis, we studied the biodistribution and pharmacokinetics of a murine anticryptococcal capsular monoclonal antibody (mAb 2H1) after intravenous and intracisternal administration. After intravenous administration of 125I-labelled 2H1 to infected rats, there was no detectable localization of 125I in the brain or cerebrospinal fluid by either gamma-camera imaging of the whole animal or organ scintillation counting. In contrast, direct intracisternal instillation of 2H1 to infected rats resulted in persistent intracranial activity. In addition, the whole body half-life of intravenously administered radio labelled mAb 2H1 was significantly reduced in infected rats compared with uninfected rats. Our observations suggest that if high central nervous system (CNS) levels of mAb are needed to achieve a therapeutic effect in human C. neoformans meningoencephalitis, direct administration of mAb into the cerebrospinal fluid or modification of the mAb to increase penetration into the CNS may be required. Furthermore, higher or more frequent dosing of mAb may be required to maintain therapeutic levels in the presence of infection. This study demonstrates the usefulness of the rat as an experimental system for studying issues related to cryptococcosis.

In the present study, using sodium dodecyl sulphate-polyacrylamide gel electrophoresis and Western blot techniques, the patterns of proteins extracted from C. neoformans yeast cells were analysed. A major 105 kilodalton (kDa) antigen that binds to Concanavalin A and cross-reacts with anti-mannan antibodies was identified. The 105 kDa mannoprotein, highly expressed in the acapsular mutant of C. neoformans with respect to the encapsulated strain, is involved in the lymphoproliferative response of T lymphocytes to Cryptococcus-sensitized monocytes.

Contact-sensing or thigmotropism is the directional growth response of cells in relation to topographical guidance cues. Thigmotropism is thought to play a major role in the location of infectable sites on plants by phytopathogenic fungi and has recently been shown to be a property of hyphae in the human pathogenic fungus Candida albicans. Here we show that hyphae of the dermatophytes Epidermophyton floccosum, Microsporum canis and Trichophyton mentagrophytes reorientate their direction of growth in response to grooves and pores of membrane substrata as did hyphae of the saprophytes Mucor mucedo and Neurospora crassa. This suggests that the thigmotropic behaviour of hyphae is not a specific property of pathogens, but rather a general feature of the growth of fungal hyphae that must forage for nutrients on surfaces and within solid materials.

Sporothrix schenckii (1099-18) cell wall peptido-rhamnomannan (CWPR) was fractionated by affinity chromatography with Concanavalin A. The Con A-bound and Con A-unbound fractions were probed with an anti-S. schenckii rabbit serum. We identified within the Con A-bound fraction three main antigens with approximate molecular weights of 84, 70 and 58 kDa. Glycopeptide beta-elimination reduced rabbit antiserum reactivity for the 84 kDa antigen (gp84) with concomittant enhanced reactivity for the 70 kDa antigen (gp70). By Western blot with Con A-HRP conjugate we demonstrated that gp84 strongly reacted with this lectin and this was the predominant antigen identified. The gp84 antigen was also demonstrated to be present on other S. schenckii strains.

Two atopic siblings presented with unilateral chronic scaly plantar lesions. Histology revealed the presence of fungi with unusual morphological aspects. Scopulariopsis brevicaulis and Phoma spp., respectively, grew on repeated cultures. Dermatophytes were absent. Such opportunistic fungal infections of the stratum corneum are extremely rare.