关键词: 葡萄孢弗隆那霉;致病力;暗色丝孢霉病;动物实验

Abstract:

Objective To study the difference in pathogenicity and genotype between two isolates of Veronaeae botryosa with different temperature tolerance. Methods Two strains of Veronaeae botryose were isolated from two patients with phaeohyphomycosis in Jiangsu and Henan province respectively. Of them, the Jiangsu strain could grow well at 37 ℃, but Henan strain could not grow at 36 ℃. Eighty mice were equally classified into immunocompetent and immuno-suppressed （induced by cyclophosphamide） groups to be inoculated with the two strains of Veronaeae botryosa respectively. Ten mice remained uninoculated and served as the control. The general condition, growth and organic involvement of mice were observed for 4 weeks followed by the killing of surviving mice. Homogenated tissue samples were obtained from liver, spleen, lung, kidney and brain; then, tissue culture, direct microscopy and pathological examination were performed. Genomic DNA was extracted from tissue samples and subjected to random amplified polymorphic DNA （RAPD） analysis. PCR was performed to amplify the internal transcribed spacer （ITS） of rDNA followed by sequencing. Results Systemic phaeohyphomycosis was induced in both immunocompetent and immuno-suppressed mice by the Jiangsu strain of Veronaeae botryose; the mortality was 30% in immunocompetent mice and 65% in immuno-suppressed mice with statistical significance between the two groups. In immuno-suppressed mice inoculated with the Jiangsu strain, the infection rate was 100% in the lung，significantly higher than in other organs; on direct microscopy the infection rate reached 64.7% in the liver, and 70.5% on tissue culture. There was no significant difference in the infection rate among these organs in immunocompetent mice inoculated with the Jiangsu strain, with the infection rate being 57.8% in the lung and 42.1% in the liver. Increased infection rate was observed in the lung of immuno-suppressed mice compared with immunocompetent mice （P < 0.05）. No definite infection was seen in immunocompetent or immuno-suppressed mice innoculated with the Henan strain. RAPD analysis and sequencing revealed that there was a base variation （A/G） at position 236 of ITS gene between the two strains. Conclusions The two strains of Veronaeae botryosa have different genotypes. Systemic phaeohyphomycosis can be caused in immunocompetent and immuno-suppressed mice by the Veronaeae botryosa isolate from Jiangsu Province; the mortality was higher in immuno-suppressed mice than in immunocompetent mice. The pathogenicity of Veronaeae botryose is associated with the immune status of hosts. In immuno-suppressed mice, lung is the organ most susceptible to infection by Veronaeae botryosa.