检测滤纸干血滴中间日疟原虫(英文)

从滤纸干血滴上用Chelex处理洗脱下的疟原虫DNA,经套式PCR扩增间日疟原虫SSUrRNA基因特异性121bp片段,分析该方法的敏感性和特异性。37例血样检测结果全部阳性,当原虫密度低至25个原虫/uL血时仍可成功检测到该特异条带,且其它三种人疟原虫(恶性疟原虫,三日疟原虫和卵形疟原虫)血样均为阴性。提示滤纸干血滴与PCR扩增技术相结合,是疟疾诊断或流行病学调查的实用工具。     

环介导等温扩增技术检测间日疟原虫方法的建立及应用分析

目的建立一种快速、简便的检测间日疟原虫的环介导等温扩增方法（LAMP）并与常规PCR方法作比较。方法根据间日疟原虫环子孢子蛋白（CSP）基因序列合成2对特异性LAMP引物,优化Mg2＋浓度、dNTPs浓度、BstDNA聚合酶添加量、反应温度、时间以及设计引物缺省试验。评估优化后的LAMP反应的特异性和灵敏性。检测133份患者血样,以显微镜检方法为金标准,比较LAMP和多重PCR法检测间日疟原虫的敏感性和特异性。结果 LAMP法检测重组质粒DNA（Pv-rDNA）的灵敏度达到10-10,为传统PCR方法的100倍。镜检确诊的68例间日疟、43例恶性疟和22例非疟疾患者中,LAMP法和多重PCR检测间日疟原虫的敏感性为98.53%和97.06%,两法基本相当（χ2=0.34,P〉0.05）;特异性为86.15%和100%,LAMP法低于多重PCR法,差异有统计学意义（χ2=9.67,P〈0.05）。LAMP法的阳性预测值和阴性预测值分别为88.16%和98.25%,多重PCR的阳性预测值和阴性预测值分别为100%和97.01%。结论 LAMP法检测间日疟原虫具有快速简便、敏感性高、设备要求低的特点,具有较好的应用前景。     

套式PCR检测滤纸干血滴中间日疟原虫

从滤纸干血滴上用Ｃｈｅｌｅｘ处理洗脱下的疟原虫ＤＮＡ,经套式ＰＣＲ扩增间日疟虫ＳＳＵｒＲＮＡ基因特异性１２１ｂｐ片段,分析该方法的敏感性和特异性。３７例血栓检测结果一部阳性,当原虫密度低全２５个原虫／ｕＬ血时仍可成功检测到该特异条带,且其它三种人疟原虫（恶性疟虫,三日疟原虫和卵疟原虫）血样均为阴性。提示滤纸干血滴与ＰＣＲ扩增技术相结合,是疟疾诊断或流行病学调查的实用工具。     

疟原虫的形态学及快速免疫诊断研究与临床应用

疟疾的实验室诊断对于临床治疗至关重要,诊断失误会造成患者误诊、漏诊甚至死亡。血涂片的染色镜检是疟疾实验室诊断的金标准。本研究旨在对感染人体的4种疟原虫:恶性疟原虫P.falciparum、间日疟原虫P.vivax、以及卵形疟原虫P.ovale和三日疟原虫P.malaiae在红细胞中的各期形态进行系统梳理,以提高形态诊断过程中的准确率。本文对2018年疑似疟疾样本的快速检测试剂条(RDT)和镜检形态学检测结果进行比较。结果发现,虽然RDT检测快速、易于操作,但镜检仍然是疟疾确诊的金标准。同时定期形态学培训及质控考核应该成为疟疾检测实验室的常规工作。     

直接PCR法检测血液中伊氏锥虫感染

为建立伊氏锥虫动基体DNA(KinetoplastDNA,kDNA)的PCR扩增技术,血液直接PCR法检测伊氏锥虫的感染,本文以伊氏锥虫kDNA片段为靶扩增DNA设计引物,确定最适PCR反应条件,建立kDNA片段的PCR扩增技术,应用直接扩增缓冲液(Ampdirect)从感染小鼠的滤纸血标本直接PCR检测伊氏锥虫。结果发现,PCR扩增伊氏锥虫kDNA片段分子量为364bp,能检测的最小DNA量是0·06pg,与布氏锥虫、活动锥虫没有交叉反应。应用直接扩增缓冲液不需进行样本的DNA抽提,直接PCR能检测感染小鼠的早期滤纸血样本,敏感性高于镜检法。本实验建立的直接PCR法检测伊氏锥虫具有较高的敏感性和特异性,方法快捷,可进一步应用于伊氏锥虫病的早期诊断以及现场调查。     

应用多聚酶链反应技术检测疟原虫的初步研究

根据编码恶性疟原虫(P．f)红细胞结合抗原(EBA-175)的部分DNA片段和间日疟原虫(P．v．)小亚基核糖体RNA基因序列设计合成恶性疟原虫和间日疟原虫的特异性引物各一对并进行多聚酶链反应(PCR)检测恶性疟和间日疟病人标本。扩增产物经琼脂糖电泳分析，可见在P．f.样本中扩增出特异的492bp大小的DNA片段，P．v．样本中扩增出特异的714bp大小的DNA片段。而在健康人血的白细胞、伯氏疟原虫样本和食触猴疟原虫样本中均不能扩增出以上片段。其结果与镜检符合率分别达95％和93.3％以上，表明该方法是一种特异、敏感的检测方法。     

用单克隆抗体免疫全银染色法诊断恶性疟的初步研究

用杂交瘤技术已产生出11株针对恶性疟原虫红内期抗原的单克隆抗体,其中3株单克隆抗体-11G5、13A2和14D9可用于双抗夹心免疫金银染色法检测恶性疟病人血中抗原。当用11G5和13A2作为捕获抗体,以胶体金标记的14D9作为探针检测恶性疟疾病人感染血时均显示出较好的效果,实验中共检测30份恶性疟病人感染血和30份健康血,结果11G5和14D9夹心时阳性检出率为96.7％(29/30),并与健康人血样品无明显的假阳性反应;13A2与14D9夹心时血阳性检出率为93.3％(28/30),假阳性率为3.3％(1/30)。此外,1株针对猴间日疟抗原的     

荧光定量分型PCR、多重PCR和测序检测HBV基因型的方法学比较

目的 比较荧光定量分型PCR、直接测序和多重PCR三种HBV基因分型法,对本实验室建立的荧光定量分型PCR方法进行评价.方法 用多重PCR、直接测序和荧光定量分型PCR法检测113份HBV DNA阳性的临床样本.结果 荧光定量分型PCR和直接测序法检出率100%,多重PCR法检出率94.69%,6份样本未能分型.荧光定量分型PCR和多重PCR的Kappa系数0.915,荧光定量分型PCR和直接测序法的Kappa系数0.742,一致性均较好.对B/C基因型混合感染样本,荧光定量分型PCR法检出28例(24.78%),多重PCR法检出19例(16.81%),直接测序法检出13例(11.50%).结论 荧光定量分型PCR分型结果准确可靠,对基因型混合感染样本的检出率明显高于多重PCR及直接测序法,是一种高效、简便、快速、准确的HBV基因分型法,适用于大规模流行病学调查.     

人体组织切片的Giemsa染色法诊断输入性疟疾

疟疾可根据流行病学史、临床表现以及实验室检查结果等进行诊断,疟原虫是疟疾的病原体.显微镜观察血涂片来检查疟原虫或疟原虫抗原阳性是实验室确诊疟疾的关键.利用人体组织切片查见疟原虫,取代血涂片镜检确诊疟疾在国内尚未见报道.笔者在法医病理鉴定中遇到1例,对组织切片进行了Giemsa染色,并尝试摸索最适宜的染色条件,清楚地显示了疟原虫在脑、肝脏组织深部血管内的形态及发育状况,现报道如下.     

吉林省延边地区一例输入性卵形疟复发病例亚型鉴定及基因特征分析

为确诊一例输入性卵形疟复发病例并鉴定其亚型,采集已开始服用青蒿素哌喹片的输入性卵形疟复发病例患者静脉血,通过薄血膜涂片吉姆萨染色镜检查看其形态特征,采用巢式PCR方法扩增其18S rRNA特异性基因,鉴定其疟原虫种类,再通过基因测序进行同源性比对和遗传进化分析。薄血膜涂片吉姆萨染色镜检结果显示,该患者血液红细胞中疟原虫已开始萎缩破裂,形态不典型,巢式PCR检测为卵形疟原虫强阳性。基因序列分析显示其序列与NCBI GenBank卵形疟Curtisi亚型序列同源性达99%。     

Detection and species determination of malaria parasites by PCR: comparison with microscopy and with ParaSight-F and ICT malaria Pf tests in a clinical environment

A rapid procedure for the diagnosis of malaria infections directly from dried blood spots by PCR amplification was evaluated with samples from 52 patients. Plasmodium infections were identified with a genus-specific primer set, and species differentiation between Plasmodium falciparum and Plasmodium vivax was analyzed by multiplex PCR. The PCR test with any of the three primer sets was able to detect as few as four parasites per microliter by gel electrophoresis or by nonisotopic paper hybridization chromatography. The diagnoses obtained by PCR correlated closely with those obtained by Giemsa staining except for two samples observed to have mixed P. falciparum-P. vivax infections. These were initially missed by microscopic analysis. In comparison with antigen-capture assays for P. falciparum, the PCR assays were able to detect three infections that were missed by the ParaSight-F test. The PCR test was negative for nine ParaSight-F-positive samples and one ICT Malaria Pf-positive sample, and these were confirmed to be false-positive results. The PCR thus gave no false-negative or false-positive results. Patients undergoing antimalarial therapy were also monitored by the PCR assay. Four of seven patients who were PCR positive for P. vivax at the time of discharge were later readmitted to the hospital with a recurrence of P. vivax infection. We would like to propose that PCR is a sensitive and easy method that can serve as a useful addition to microscopy for the diagnosis and the clinical monitoring of treatment of malaria.     

Real-time PCR for detection and identification of Plasmodium spp

Rapid and accurate detection of malaria parasites in blood is needed to institute proper therapy. We developed and used a real-time PCR assay to detect and distinguish four Plasmodium spp. that cause human disease by using a single amplification reaction and melting curve analysis. Consensus primers were used to amplify a species-specific region of the multicopy 18S rRNA gene, and SYBR Green was used for detection in a LightCycler instrument. Patient specimens infected at 0.01 to 0.02% parasitemia densities were detected, and analytical sensitivity was estimated to be 0.2 genome equivalent per reaction. Melting curve analysis based on nucleotide variations within the amplicons provided a basis for accurate differentiation of Plasmodium falciparum, P. vivax, P. ovale, and P. malariae. For assay validation, 358 patient blood samples from the National University Hospital in Singapore and Evanston Northwestern Healthcare in Illinois were analyzed. Of 76 blinded patient samples with a microscopic diagnosis of P. falciparum, P. vivax, or P. ovale infection, 74 (97.4%) were detected by real-time PCR, including three specimens containing mixed P. falciparum-P. vivax infections. No Plasmodium DNA was amplified in any of the 82 specimens sent for malaria testing but that were microscopically negative for Plasmodium infection. In addition, 200 blood samples from patients whose blood was collected for reasons other than malaria testing were also determined to be negative by real-time PCR. Real-time PCR with melting curve analysis could be a rapid and objective supplement to the examination of Giemsa-stained blood smears and may replace microscopy following further validation.     

Usefulness of Seminested Multiplex PCR in Surveillance of Imported Malaria in Spain

The use of a new PCR-based method for the diagnosis of malaria in the Spanish Malaria Reference Laboratory has promoted an increase in confirmed cases of malaria. From August 1997 to July 1998, a total of 192 whole-blood samples and 71 serum samples from 168 patients were received from the hospitals of the Spanish National Health System. Most of the patients came from west-central African countries (85%). This molecular method showed more sensitivity and specificity than microscopy, detecting 12.4% more positive samples than microscopy and 13% of mixed infections undetectable by Giemsa stain. Plasmodium falciparum was the main species detected, with 68% of the total positive malaria cases, followed by Plasmodium malariae (29%), Plasmodium vivax (14%), and Plasmodium ovale (7%), including mixed infections in all cases. This report consists of the first wide, centralized survey of malaria surveillance in Spain. The reference laboratory conducted the analysis of all imported cases in order to detect trends in acquisition. The use of a seminested multiplex PCR permitted confirmation of the origins of the infections and the Plasmodium species involved and confirmation of the effectiveness of drug treatments. This PCR also allowed the detection of the presence in Spain of primaquine-tolerant P. vivax strains from west-central Africa, as well as the detection of a P. falciparum infection induced by transfusion.     

Applied genomics: data mining reveals species-specific malaria diagnostic targets more sensitive than 18S rRNA

Accurate and rapid diagnosis of malaria infections is crucial for implementing species-appropriate treatment and saving lives. Molecular diagnostic tools are the most accurate and sensitive method of detecting Plasmodium, differentiating between Plasmodium species, and detecting subclinical infections. Despite available whole-genome sequence data for Plasmodium falciparum and P. vivax, the majority of PCR-based methods still rely on the 18S rRNA gene targets. Historically, this gene has served as the best target for diagnostic assays. However, it is limited in its ability to detect mixed infections in multiplex assay platforms without the use of nested PCR. New diagnostic targets are needed. Ideal targets will be species specific, highly sensitive, and amenable to both single-step and multiplex PCRs. We have mined the genomes of P. falciparum and P. vivax to identify species-specific, repetitive sequences that serve as new PCR targets for the detection of malaria. We show that these targets (Pvr47 and Pfr364) exist in 14 to 41 copies and are more sensitive than 18S rRNA when utilized in a single-step PCR. Parasites are routinely detected at levels of 1 to 10 parasites/μl. The reaction can be multiplexed to detect both species in a single reaction. We have examined 7 P. falciparum strains and 91 P. falciparum clinical isolates from Tanzania and 10 P. vivax strains and 96 P. vivax clinical isolates from Venezuela, and we have verified a sensitivity and specificity of ～100% for both targets compared with a nested 18S rRNA approach. We show that bioinformatics approaches can be successfully applied to identify novel diagnostic targets and improve molecular methods for pathogen detection. These novel targets provide a powerful alternative molecular diagnostic method for the detection of P. falciparum and P. vivax in conventional or multiplex PCR platforms.     

Evaluation of rapid immunocapture assays for diagnosis of Plasmodium vivax in Korea

The rapid immunocapture assays, OptiMal and ICT, were evaluated from 87 individuals for the diagnosis of malaria infections directly from whole blood. A total of 87 individuals was examined for malaria parasites by microscopic examination of Giemsa-stained blood smears, and 65 cases were positive for Plasmodium vivax by microscopy. Correspondingly, the OptiMal test identified malaria infection in 45 cases (69.2%) of microscopy positive cases. Of these, two cases were misinterpreted as Plasmodium falciparum, whereas ICT detected P. vivax infection in 29 (44.6%) patients. We would like to propose that rapid immuno capture assays are an easy method that can serve as a useful tool in addition to microscopy for the diagnosis of malaria, but sensitivity is not yet satisfactory for diagnosis of P. vivax in Korea.     

Multiplex 5' nuclease-quantitative PCR for diagnosis of relapsing fever in a large Tanzanian cohort

Relapsing fever (RF) is caused by tick- and louse-borne Borrelia spp., is characterized by recurrent fever, and is often misdiagnosed as malaria. Because of submicroscopic bacteremia, microscopy can be insensitive between febrile bouts. We designed a multiplex quantitative PCR (qPCR) assay to distinguish RF Borrelia from Plasmodium falciparum and P. vivax. The assay specifically (100%) amplified pathogenic RF Borrelia (1 copy/reaction). We then tested blood from participants within a Tanzanian cohort assessed at scheduled intervals and with fever. Among 8,617 blood samples from 2,057 participants surveyed routinely, 7 (0.08%) samples and 7 (0.3%) participants had RF DNA (median, 4.4 × 10(3) copies/ml). Of 382 samples from 310 febrile persons, 15 (3.9%) samples from 13 (4.2%) participants had RF DNA (median, 7.9 × 10(2) copies/ml). Five (1.3%) samples from 4 (1.3%) participants were found to harbor Borrelia by microscopy. We conclude that multiplex qPCR holds promise for improved clinical diagnosis and epidemiologic assessment of RF.     

Comparison of the OptiMAL Test with PCR for Diagnosis of Malaria in Immigrants

The OptiMAL test (Flow Inc., Portland, Oreg.), which detects a malaria parasite lactate dehydrogenase (pLDH) antigen, has not been evaluated for its sensitivity in the diagnosis of malaria infection in various epidemiological settings. Using microscopy and a PCR as reference standards, we performed a comparison of these assays with the OptiMAL test for the detection of Plasmodium falciparum and Plasmodium vivax infection in 550 immigrants who had come from areas where malaria is endemic to reside in Kuwait, where malaria is not endemic. As determined by microscopy, 125 (23%) patients had malaria, and of these, 84 (67%) were infected with P. vivax and 36 were infected with P. falciparum; in 5 cases the parasite species could not be determined due to a paucity of the parasites. The PCR detected malaria infection in 145 (26%) patients; 102 (70%) of the patients had P. vivax infection and 43 had P. falciparum infection. Of the five cases undetermined by microscopy, the PCR detected P. falciparum infection in two cases, P. vivax infection in two cases, and mixed (P. falciparum plus P. vivax) infection in one case. Correspondingly, the OptiMAL test detected malaria infection in 95 patients (17%); of these, 70 (74%) had P. vivax infection and 25 were infected with P. falciparum. In this study, 61 (49%) of the 125 malaria cases, as confirmed by microscopy, had a degree of parasitemia of <100 parasites per microl, and 23 (18%) of the cases had a degree of <50 parasites per microl. Our results show that the sensitivity of the OptiMAL test is high (97%) at a high level of parasitemia (>100 parasites/microl) but drops to 59% when the level is <100 parasites/microl and to 39% when it is <50 parasites/microl. In addition, the OptiMAL test failed to identify four patients whose blood smears contained P. falciparum gametocytes only. We conclude that the sensitivity and specificity of the OptiMAL test are comparable to those of microscopy in detecting malaria infection at a parasitemia level of >100 parasites/microl; however, the test failed to identify more than half of the patients with a parasitemia level of <50 parasites/microl. Thus, the OptiMAL test should be used with great caution, and it should not replace conventional microscopy in the diagnosis of malaria infection.     

Molecular test for vivax malaria with loop-mediated isothermal amplification method in central China

Vivax malaria has the highest incidence in central China. High-throughput and cost-effective testing methods are essential for vivax malaria diagnosis in this area. Loop-mediated isothermal amplification (LAMP) is an established nucleic acid amplification method, which provides a promising platform for the molecular detection of malaria parasites in development countries. This study was performed to compare the LAMP method, the nested PCR-based method, and microscopic examinations in diagnosing vivax malaria. LAMP detected vivax malaria parasites in 160 of 164 microscopically positive samples (sensitivity, 97.6%), whereas nested PCR detected Plasmodium vivax in 162 of 164 samples (sensitivity, 98.8%). No false-positive results were obtained by LAMP or nested PCR among fever-positive and healthy samples. The sensitivities and specificities of the two molecular tests were consistently high. In addition, the reproducibility of the LAMP assays using water bath, which reduced the cost substantially. LAMP method is an accurate, rapid, simple, and cost-effective method that may be useful for diagnosis in field diagnoses instead of nested PCR. This method is feasible to diagnose vivax malaria parasite in endemic areas of central China.