Role of AFR1, an ABC transporter-encoding gene, in the in vivo response to fluconazole and virulence of Cryptococcus neoformans
Role of AFR1, an ABC transporter-encoding gene, in the in vivo response to fluconazole and virulence of Cryptococcus neoformans
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DOI：
10.1128/iai.74.2.1352-1359.2006
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发表时间：
2006-02-01
影响因子：
3.1
通讯作者：
Fadda, G
中科院分区：
文献类型：
--
作者：
Sanguinetti, M;Posteraro, B;Fadda, G
我们最近证明，在新生隐球菌中ATP结合盒（ABC）转运蛋白编码基因AFR 1的上调参与了该酵母菌对氟康唑的体外耐药性。在本研究中，我们研究了AFR 1在全身性隐球菌病小鼠模型中对氟康唑的体内反应中的作用。小鼠感染野生型氟康唑敏感株。新生儿，菌株BPY 22;在体外对氟康唑表现出高敏感性的afr 1突变株BPY 444或在体外对氟康唑表现出耐药性的afr 1过表达菌株BPY 445。在三组中的每一组中，感染动物被随机分配到氟康唑治疗或未治疗对照亚组。正如预期的那样，氟康唑延长了BPY 22和BPY 444感染小鼠的存活时间并降低了真菌组织负荷（与未治疗相比），而对BPY 445感染小鼠无显著影响。当研究这些菌株在小鼠中的致病性时，在吸入或静脉内接种后，菌株BPY 445比BPY 22的毒力显著更强，但是仅当通过呼吸道获得感染时，用BPY 444感染的小鼠比BPY 22感染的动物存活显著更长。在体外巨噬细胞感染研究中，菌株BPY 445与菌株BPY 22和BPY 444相比也显示出增强的细胞内存活，这表明其增强的毒力可能是由于其对吞噬细胞产生的抗微生物因子的脆弱性降低。这些发现表明，AFR 1基因的上调是决定体内氟康唑耐药性或影响新生隐球菌毒力的重要因素。
We have recently demonstrated that upregulation of the ATP binding cassette (ABC) transporter-encoding gene AFR1 in Cryptococcus neoformans is involved in the in vitro resistance to fluconazole of this yeast. In the present study, we investigated the role of AFR1 in the in vivo response to fluconazole in a mouse model of systemic cryptococcosis. Mice were infected with a wild-type fluconazole-susceptible strain of C. neoformans, strain BPY22; an afr1 mutant, BPY444, which displayed hypersusceptibility to fluconazole in vitro; or an AFR1-overexpres sing strain, BPY445, which exhibited in vitro resistance to the drug. In each of the three groups, infected animals were randomly assigned to fluconazole treatment or untreated-control subgroups. As expected, fluconazole prolonged survival and reduced fungal tissue burdens (compared with no treatment) in BPY22- and BPY444-infected mice, whereas it had no significant effects in mice infected with BPY445. When the pathogenicities of these strains in mice were investigated, strain BPY445 was significantly more virulent than BPY22 following inhalational or intravenous inoculation, but mice infected with BPY444 survived significantly longer than BPY22-infected animals only when infection was acquired via the respiratory tract. In in vitro macrophage infection studies, strain BPY445 also displayed enhanced intracellular survival compared with strains BPY22 and BPY444, suggesting that its increased virulence may be due to its reduced vulnerability to the antimicrobial factors produced by phagocytic cells. These findings indicate that the upregulation of the AFR1 gene is an important factor in either determining the in vivo resistance to fluconazole or influencing the virulence of C neoformans.