[Identification of pathogens in the vitreous of patients with infectious uveitis by metagenomic sequencing].

Objective: To investigate the role of metagenomic sequencing in the diagnosis of infectious uveitis. Methods: Cross-sectional study. A total of 19 vitreous specimens of patients with suspected infectious uveitis from March 2016 to July 2018 in Beijing Tongren Hospital were collected, including 8 males and 11 females, 19 to 68 years old. There were 10 cases in the right eye, 8 cases in the left eye and 1 case in both eyes. Acute retinal necrosis was clinically diagnosed in 8 patients (9 eyes), and the diagnosis was unknown in 11 patients (11 eyes). About 1 ml of the vitreous fluid was reserved for each specimen, 800 μl for metagenomic sequencing and 200 μl for real-time fluorescence quantitative PCR verification. The TIANamp Micro DNA Kit was used to extract the sample DNA for metagenomic sequencing, and the ultrasonic fragment was broken to 200-300 bp. The BGISEQ-500 platform was used for sequencing. The data with low quality and length less than 35 bp were cleared from the sequencing data to obtain high-quality data. Through biological authentication software, the reference human genome sequence and low complexity were removed from high-quality data. The data obtained were compared with a special microorganism database regarding the percentage of microbial sequences, the number of unique sequences, coverage and sequencing depth, so as to determine positive sequencing parameters, which were classified into bacteria, viruses, fungi and parasites. Real-time fluorescence quantitative PCR was performed to validate the accuracy. Results: A variety of microorganisms were detected by metagenomic sequencing in 19 specimens, including 3 cases of varicella zoster virus, 2 cases of Candida albicans, 1 case of Propionibacterium acnes and 1 case of Haemophilus parainfluenzae. The percentage of microbial sequences was 77.93% （1 794/2 302）, 99.98% （12 843/12 845） and 98.88%（5 733/5 798）, and the number of unique sequences was 1 794, 12 843 and 57 33 in varicella zoster virus cases, respectively. The verification of varicella zoster virus by PCR was consistent with that by metagenomic sequencing. Conclusion: Metagenomic sequencing can be used as an alternative method for laboratory diagnosis of infectious uveitis. (Chin J Ophthalmol, 2020, 56: 519-523).目的： 探讨宏基因组测序（MGS）技术在感染性葡萄膜炎诊断中的作用。 方法： 横断面研究。对2016年3月至2018年7月首都医科大学附属北京同仁医院临床疑诊为感染性葡萄膜炎的19例患者的19份玻璃体标本进行MGS检测。患者中男性8例，女性11例，年龄19~68岁；右眼10例，左眼8例，双眼1例；临床诊断急性视网膜坏死8例（9只眼），诊断不明11例（11只眼）。每份标本留取玻璃体约1 ml，800 μl标本用于MGS，200 μl标本用于实时荧光定量PCR的验证实验。MGS使用TIANamp Micro DNA Kit试剂盒提取样本DNA，BGISEQ-500平台测序。将测序数据中低质量和长度小于35 bp的数据、人类参考基因组序列及低复杂度序列去除后，获得的数据与专用微生物数据库比对分析，通过统计对比序列数占比、唯一序列数、覆盖率、测序深度等参数确定测序阳性结果，使用实时荧光定量PCR方法对上述结果准确性进行验证。 结果： 19份标本MGS检出多种微生物，7份测序结果为阳性。其中3份为水痘-带状疱疹病毒、2份为白念珠菌、1份为痤疮丙酸杆菌、1份为副流感嗜血杆菌。3份水痘-带状疱疹病毒标本检出的序列数占比分别为77.93%（1 794/2 302）、99.98%（12 843/12 845）、98.88%（5 733/5 798），唯一序列数分别为1 794、12 843、5 733条；实时荧光定量PCR验证结果显示此3份标本水痘-带状疱疹病毒载量均较高，与MGS结果一致。 结论： MGS可作为感染性葡萄膜炎实验室诊断方法的一种选择。（中华眼科杂志，2020，56：519-523）.