摘要
目的了解我国分离的VGⅠ及VGⅡ型格特隐球菌在体外的生长特性及对蜡螟的毒力差异.方法在对我国分离的8株格特隐球菌多位点序列分型的基础上,通过体外培养法绘制生长曲线、观察黑色素生成并测量荚膜厚度.利用蜡螟感染试验检测格特隐球菌的半数致死时间(LT50)和在48 h的半数致死浓度(LC50).同时采用14株新型隐球菌作为对比研究.结果8株格特隐球菌中有6株VGⅠ型,2株VGⅡ型.30℃培养,VGⅠ及VGⅡ型格特隐球菌与新型隐球菌的生长曲线基本一致,它们在96 h各自生长的总菌数均可达10^8 CFU/ml;37℃培养,它们在所有测试时间点的总菌数均不及30℃培养.新型隐球菌在30℃和37℃培养黑色素产生量无差异,但格特隐球菌VGⅠ型和VGⅡ型均显示37℃培养产生的黑色素量多于30℃.格特隐球菌VGⅠ型在37℃的荚膜-细胞壁直径比值大于30℃,差异具有统计学意义(P<0.001).蜡螟体内毒力试验显示,新型隐球菌、格特隐球菌VGⅠ型和VGⅡ型的LT50长短排序为:格特隐球菌VGⅡ型<格特隐球菌VGⅠ型<新型隐球菌.1×106 CFU/ml浓度下,格特隐球菌VGⅡ型的LT50为72 h.48 h只有格特隐球菌VGⅡ型对蜡螟致死数过半,LC50为1×10^8 CFU/ml.结论新型隐球菌、格特隐球菌VGⅠ型和VGⅡ型均在30℃培养条件下较37℃繁殖更快,但格特隐球菌在37℃时产生的黑色素量以及形成荚膜的厚度均大于30℃培养时.VGⅡ型格特隐球菌对蜡螟的半数致死时间最短,毒力最强.
Objective To understand the in vitro growth characteristics of Cryptococcus gattii VGⅠand VGⅡisolated in China and the diversity in their virulence to Galleria mellonella.Methods Based on the results of multilocus sequence typing for eight strains of Cryptococcus gattii isolated in China,the strains were cultured in vitro to draw growth curves,observe the melanin production and measure the capsule thickness.The median lethal time(LT50)and median lethal dose(LC50)at 48 h of Cryptococcus gattii were calculated using Galleria mellonella infection test.Fourteen strains of Cryptococcus neoformans were studied for comparison.Results The eight Cryptococcus gattii strains were six VGⅠand two VGⅡ.The growth curves of Cryptococcus gattii VGⅠand VGⅡwere similar to that of Cryptococcus neoformans when culture at 30℃.The total number for each of them could reach 10^8 CFU/ml at 96 h under 30℃.However,the total number at any time point at 37℃was less than that at 30℃.There was no significant difference in the amount of melanin produced by Cryptococcus neoformans under 30℃and 37℃,but both VGⅠand VGⅡtypes of Cryptococcus gattii could produce more amount of melanin under 37℃than under 30℃.The ratio of capsule/cell wall diameter of Cryptococcus gattii VGⅠwas greater at 37℃than that at 30℃with statistical significance(P<0.001).Cryptococcus neoformans showed the longest LT50,followed by VGⅠand VGⅡtypes of Cryptococcus gattii.The LT50 of Cryptococcus gattii VGⅡat the concentration of 1×106 CFU/ml was 72 h,and its LC50 at 48 h was 1×10^8 CFU/ml.Conclusions Like Cryptococcus neoformans,Cryptococcus gattii VGⅠand VGⅡgrew faster under 30℃than under 37℃,but more melanin was produced and thicker capsule was formed under 37℃than under 30℃.Among Cryptococcus neoformans and VGⅠand VGⅡtypes of Cryptococcus gattii,Cryptococcus gattii VGⅡshowed the shortest LT50 and the strongest virulence to Galleria mellonella.
作者
杨晨
金亮
王丽凤
薛新颖
沈定霞
Yang Chen;Jin Liang;Wang Lifeng;Xue Xinying;Shen Dingxia(Medical Laboratory Center,the First Medical Center of Chinese PLA General Hospital,Beijing 100853,China)
出处
《中华微生物学和免疫学杂志》
CAS
CSCD
北大核心
2019年第10期725-730,共6页
Chinese Journal of Microbiology and Immunology
基金
国家自然科学基金青年项目(81700007)
解放军总医院转化医学项目(2018TM-12)。
关键词
格特隐球菌
分子型
生长特性
蜡螟
毒力
Cryptococcus gattii
Molecular type
Growth characteristics
Galleria mellonella
Vir-ulence
