SMRT sequencing and ddPCR reveal the complexity of developmental trajectories and temporal dynamics of gut bifidobacterial communities in infants

Infant intestinal microbiome is closely linked with health and risk of disease. Bifidobacterium are important components of the infant gut and are known to confer various health effects on the host. However, few studies have described the precise composition and dynamics of early infant gut bifidobacterial communities. Thus, this was a pilot study aiming to describe the developmental trajectories and temporal dynamics of bifidobacterial communities in infants before 6 months of age. A total of 28 fecal samples from 4 infants(GF, ZZ, QM, TN, respectively)were collected and analyzed after 5, 15, 30, 60, 90, 120, 150, and 180 days of birth by a bifidobacteria-target method(based on single-molecule real-time sequencing of partial bifidobacterial rpsK genes)in conjunction with droplet digital polymerase chain reaction(ddPCR). The infant fecal microbiota comprised a total of 11 bifidobacterial species, including 4 major species, i.e., B. dentium(37.35%), B. catenulatum(32.04%), B. breve(22.24%), and B. animalis(8.02%). The infant microbiota showed highly individualized developmental trajectories. The leading species for GF was B. catenulatum, with a relatively stable developmental trajectory. In ZZ, B. breve was enriched, and the developmental trajectory was rather fluctuating. The most abundant species for QM and TN was B. dentium. The developmental trajectory of B. dentium in QM showed a trend of gradual decrease, whereas an opposite trend was seen in samples of TN. The results of ddPCR confirmed large variations in quantities of bifidobacteria between infants and suggested discordances in temporal dynamics of bifidobacterial communities during the first half year of infancy. In conclusion, our results suggested that the early infant gut bifidobacterial microbiota was highly complex and temporal dynamics, with individualized developmental trajectories, which should be considered in future research of infant gut microbiota.

Next Generation Transcriptome Sequencing and Quantitative Real-Time PCR Technologies for Characterisation of the Bemisia tabaci Asia 1 mtCOI Phylogenetic Clade

A programme of functional genomics research is underway at the University of Greenwich,UK,to develop and apply genomics technologies to characterise an economically-important but under-researched Bemisia tabaci（Hemiptera：Aleyrodidae）,the Asia 1 mtCOI phylogenetic group.A comparison of this putative species from India with other important B.tabaci populations and insect species may provide targets for the development of more effective whitefly control strategies.As a first step,next-generation sequencing（NGS）has been used to survey the transcriptome of adult female whitefly,with high quality RNA preparations being used to generate cDNA libraries for NGS using the Roche 454 Titanium DNA sequencing platform.Contig assemblies constructed from the resultant sequences（301 094 reads）using the software program CLC Genomics Workbench generated 3 821 core contigs.Comparison of a selection of these contigs with related sequences from other B.tabaci genetic groups has revealed good alignment for some genes（e.g.,HSP90）but misassemblies in other datasets（e.g.,the vitellogenin gene family）,highlighting the need for manual curation as well as collaborative international efforts to obtain accurate assemblies from the existing next generation sequence datasets.Nevertheless,data emerging from the NGS has facilitated the development of accurate and reliable methods for analysing gene expression based on quantitative real-time RT-PCR,illustrating the power of this approach to enable rapid expression analyses in an organism for which a complete genome sequence is currently lacking.

Evaluation of Real-Time 16S rDNA PCR and Pyrosequencing for Routine Identification of Bacteria in Joint Fluid and Tissue Specimens

16S rDNA PCR and sequencing are powerful tools for bacterial detection and identification, although their routine use is not currently widespread in the field of clinical microbiology. The availability of pyrosequencing now makes 16S rDNA assays more accessible to routine diagnostic laboratories, but this approach has had limited evaluation in general diagnostic practice. In this study we evaluated a real-time 16S rDNA PCR and pyrosequencing assay for use in a routine microbiology laboratory, by retrospectively testing joint fluid and joint tissue specimens received for conventional culture. We found that use of the real-time 16S rDNA assay was clinically valuable in this specimen type because it enabled us to identify a small number of culture-negative infections. Although faster and less labour-intensive, we found that the utility of pyrosequencing for pathogen identification is still hampered by shorter read lengths compared to conventional (Sanger) sequencing. Combining results from both molecular and conventional culture methods, bacteria were only detected in 11.8% specimens in this study. However, the detection rate was increased to 18.6% if specimens were only included from patients with a documented clinical suspicion of infection. In conclusion, while pyrosequencing had significant advantages in speed and ease-of-use over conventional sequencing, multiple reactions will be required to deliver comparable species-level identification, thus negating many of the benefits of using the technique. We found that 16S rDNA PCR and sequencing should be rationally targeted on the basis of good clinical information in the routine diagnostic setting, and not used as a general screening test for the exclusion of bacterial infection in joint specimens.

Real-Time Update of Sequence Placement Logic for High Arch Dams Based on Evidence Weight Discount

Sequence placement logic plays a significant role in construction simulation of high arch dams and directly affects the simulation process and results.To establish a sequence logic for dam block placement,the construction scheme,real-time construction process,and random factors of the site all need to be considered in detail.There are few studies available currently that take all these factors into consideration.To address this problem,a real-time update of sequence placement logic for high arch dams based on evidence weight discount is proposed in this study.First,the subjective weight of the dam block sequence priority criteria is built using a consistent matrix method based on the construction scheme.Second,using evidence theory,dynamic objective weight of the priority criteria and basic probability assignment is built.Finally,using a weight self-adaptive adjustment method and comprehensive evidence discounting,the placing probabilities of different dam blocks are obtained.A case study indicates that this method can realize realtime update of sequence placement logic.

Complete genome sequence of a Rodent Torque teno virus in Hainan Island, China and establishment of a real-time PCR for detecting Rodent Torque teno virus 3

Objective:To perform whole-genome sequencing and phylogenetic analysis of the local endemic strain of Rodent Torque teno virus (RoTTV), RoTTV3-HMU1, found in Rattus norvegicus, Haikou City, Hainan Province, and establish a SYBR Green I based real-time PCR detection assay for RoTTV3.Methods: Based on the high-throughput genome sequencing analysis, specific primers were designed and the whole genome sequence was amplified by PCR and Sanger sequencing. Specific detection primers were designed based on the conserved sequences of RoTTV3. The recombinant plasmid contained the whole genome of RoTTV3-HMU1 was constructed as a standard control. The experimental conditions were optimized and the real-time PCR detection assay of RoTTV3 was established.Results: The genomic sequence of RoTTV carried by Rattus norvegicus in Haikou City was successfully sequenced. Phylogenetic analysis indicated that the virus belongs to the RoTTV3 genotype. In this experiment, the real-time PCR detection method of RoTTV3 was established. The standard curve generated had a wide dynamic range from 1×(102-108) copies/μL, with a linear correlation (R2=1.000). The melting curve analysis using SYBR Green showed only one specific melting peak and no primer-dimmers represented. The detection limit was 100 copies/reaction.Discussion: This study was the first report of the RoTTV in Hainan Islands, and its phylogenetic analysis was of great significance to the origin and evolution of RoTTV. The RoTTV3 real-time PCR detection method established in this experiment has a high sensitivity and good specificity, which lays a technical foundation for the epidemiological investigation of RoTTV3.

Exploring the hepatitis C virus genome using single molecule realtime sequencing

Single molecular real-time(SMRT)sequencing,also called third-generation sequencing,is a novel sequencing technique capable of generating extremely long contiguous sequence reads.While conventional short-read sequencing cannot evaluate the linkage of nucleotide substitutions distant from one another,SMRT sequencing can directly demonstrate linkage of nucleotide changes over a span of more than 20 kbp,and thus can be applied to directly examine the haplotypes of viruses or bacteria whose genome structures are changing in real time.In addition,an error correction method(circular consensus sequencing)has been established and repeated sequencing of a single-molecule DNA template can result in extremely high accuracy.The advantages of long read sequencing enable accurate determination of the haplotypes of individual viral clones.SMRT sequencing has been applied in various studies of viral genomes including determination of the full-length contiguous genome sequence of hepatitis C virus(HCV),targeted deep sequencing of the HCV NS5A gene,and assessment of heterogeneity among viral populations.Recently,the emergence of multi-drug resistant HCV viruses has become a significant clinical issue and has been also demonstrated using SMRT sequencing.In this review,we introduce the novel third-generation PacBio RSII/Sequel systems,compare them with conventional next-generation sequencers,and summarize previous studies in which SMRT sequencing technology has been applied for HCV genome analysis.We also refer to another long-read sequencing platform,nanopore sequencing technology,and discuss the advantages,limitations and future perspectives in using these thirdgeneration sequencers for HCV genome analysis.

Establishment of TaqMan Real-time Quantitative PCR Assay for Foreign Gene Copy Numbers in Transgenic Soybean

TaqMan quantitative PCR technique was used to detect the copies of exogenous CaMV35S flanks sequence in transgenic soybean. With soybean lectin as the endogenous reference gene, and gene complex DNA in non-GMO soybeans as the endogenous reference standard, the gradient dilution method was used to separately calculate Ct value of endogenous reference gene and plasmid DNA and correlation standard curve equation of logarithm of copies, and then to calculate the copies of samples through substituting thus-obtained Ct into the standard curve equation. The standard curve equation of endogenous reference gene was y =–3.422x＋35.201, R2=0.998; the standard curve equation of exogenous gene was y =–3.495x＋35.303, R2=0.999. The sample copies was got by putting Ct value into the standard curve equation, and it was the ratio of exogenous gene and reference gene. We found that CaMV35S gene in transgenic soy was single copy.

Diagnosis of cytomegalovirus encephalitis using metagenomic nextgeneration sequencing of blood and cerebrospinal fluid:A case report

BACKGROUND Cytomegalovirus(CMV)infections in the population are mostly subclinical,inapparent,or latent.However,it is rare in brain tissue.Most reported CMV encephalitis cases were patients with immunodeficiency.The diagnosis and detection rate of CMV encephalitis in patients with normal immune function needs to be further improved.CASE SUMMARY An 86-year-old male was admitted due to a sudden onset of unconsciousness for 3 h.The patient developed status epilepticus and was relieved after antiepileptic treatment.Encephalitis was considered due to the high signals of diffusionweighted imaging sequences in the right central region by magnetic resonance imaging.Metagenomic next-generation sequencing(mNGS)of blood and cerebrospinal fluid revealed CMV,with unique reads number being 614 and 1,respectively.Simultaneous quantitative PCR results showed CMV positive in blood samples and negative in cerebrospinal fluid samples.The patient was finally diagnosed as CMV encephalitis with status epilepticus.After the antiviral,hormonal,andγ-globulin pulse therapy,the patient’s condition improved,and he was finally discharged.CONCLUSION mNGS could be a reliable approach for the diagnosis of CMV encephalitis,with high efficiency,sensitivity,and specificity.

重庆地区RhD变异型无偿献血者的基因多态性及其表型研究

目的对重庆地区22例RhD变异型无偿献血者标本进行Rh血型血清学检测和三代基因测序,了解重庆地区RhD变异型的表型分布及其基因分型。方法选择2023年1—8月本中心参与无偿献血的人群作为研究对象。使用传统血清学方法对其进行RhD表型鉴定,确定为RhD变异型后使用D-screen试剂盒对其进行RhD不同抗原表位的检测。此外,提取其基因组DNA,使用叠瓦式引物设计进行多段扩增、拼接获得RHD基因全长序列进行三代测序检测,并用SnapGene软件对序列结果进行分析。结果在22例RhD变异型中,8例为DVI 3型(36.36%),其存在RHD-CE(3-6)-D杂交等位基因;6例部分弱D15型(27.27%),主要发生的突变为c.845G>A;6例亚洲型Del(27.27%),主要发生的突变为c.1227G>A,还有1例弱D17型发生的突变为c.340C>T和1例推测为部分D(c.491A>T,p.Asp164Val,错义突变)。结论重庆地区无偿献血人群中最常见的RhD变异型为DVI 3型,使用SMRT三代测序技术可以获得RhD变异型单倍体全长。

SMRT测序技术及其在微生物研究中的应用

高通量测序技术的发展为研究者深入探索微生物世界提供可能。随着以Pacific Bio Sciences(PacBio)公司的单分子实时测序(Single molecule real time sequencing,SMRT)为代表的第三代测序(Third generation sequencing,TGS)技术逐渐发展成熟,微生物研究方法正面临又一次新的变革。SMRT测序技术凭借其特殊建库方式(SMRTbell)和超长的测序读长等特点,为微生物16S rRNA基因全长测序提供新的选择。同时,为组装完整可靠的宏基因组和微生物全基因组提供新方法。随着PacBio测序平台的成本大幅下降,SMRT测序技术的PacBio系列平台开始逐渐被应用于微生物16S rRNA基因测序、宏基因组测序和全基因组测序研究中。综述了SMRT测序技术的技术原理和特点及其在微生物16S rRNA基因全长测序、宏基因组测序等方面的应用,并分析了目前SMRT测序技术在微生物各方面研究中的优势和存在的问题,提出基于SMRT测序技术获得的长片段在后期分析中存在的问题。SMRT测序技术将越来越多地引入到微生物研究中,期望为将要选择使用SMRT测序技术研究微生物的研究人员提供一定参考。

基于SMRT技术的水杉全长转录组分析及基因功能注释

以水杉原生种为材料,提取其幼嫩植株的根、茎和叶的总RNA,经mRNA纯化、反转录、全长转录组文库构建等过程,再采用SMRT技术测定其全长转录本序列,运用生物信息学对获得的原始转录组数据进行分析。结果显示:提取的总RNA符合建库要求;全长转录组测序共获得了包含5914711个亚读段(subreads)的14.0 Gb的数据,质量控制处理后包括236130个全长非嵌合读段(reads)和97626个一致性reads;转录本经去冗余处理后共获得61057个全长一致性读段(unigenes),其中有54099个被成功注释到7个数据库中,注释比达88.60%;对水杉unigenes作CDS(coding sequence)长度分布及转录因子分析,其CDS长度范围为144~6477 nt,平均长度约为679 nt;共检测到2386个转录因子,这些转录因子可以归类为29个家族。

自然发酵酸马奶对人体肠道菌群的影响——基于PacBio SMRT测序技术

采用PacBio SMRT测序技术研究了内蒙古锡林郭勒盟地区一名健康志愿者在连续饮用酸马奶60 d前后肠道菌群的变化。结果表明,连续饮用酸马奶可以增加志愿者肠道菌群的丰度和多样性,使志愿者肠道菌群更加趋于健康化。此外,志愿者肠道中存在大量的"肠道核心微生物群",饮用酸马奶会使志愿者肠道中硬壁菌门的相对含量升高。在种的水平上,饮用酸马奶可以促进部分有益生菌如柔嫩梭菌群、多形拟杆菌的生长,这可能是酸马奶具有众多益生作用的原因之一。

基于PacBio SMRT技术的婴幼儿配方奶粉微生物安全性评价

目的:婴幼儿配方奶粉中的大量细菌已被灭活,然而灭活微生物仍影响产品品质和货架期。现行纯培养技术只能对食品基质中活菌进行检测,无法全面评估污染微生物组成,而基于宏基因组学策略能够对婴幼儿配方奶粉加工过程中污染微生物进行全面客观的评价。方法:采集6份婴幼儿配方奶粉,使用细菌纯培养、单分子实时测序技术(PacBio SMRT)和微滴式数字PCR(ddPCR)联用技术对其污染微生物组成进行评价。结果:采用纯培养技术在样品中均未检测到大肠菌群、沙门氏菌、金黄色葡萄球菌、阪崎肠杆菌和芽孢。使用PacBio SMRT测序技术,在婴幼儿配方奶粉中共鉴定出14个细菌门、138个细菌属和255个细菌种。其中6份样品均存在过嗜冷菌蜡样芽孢杆菌,其平均相对含量高达23.54%,这一灭活的细菌也会影响产品货架期。此外,在IF3、IF4、IF5和IF6样品中,检测到相对含量较低的致病菌大肠杆菌,其相对含量分别为0.06%,0.01%,0.15%和0.05%。采用ddPCR技术对SMRT测序方法检测到的致病菌蜡样芽孢杆菌和大肠杆菌进行定量分析,发现每克奶粉样品中蜡样芽孢杆菌和大肠杆菌的平均拷贝数取对数后分别为5.45和4.89。结论:在6份婴幼儿配方奶粉中均未检出致病菌,符合食品安全国家标准,然而奶粉中被灭活的蜡样芽孢杆菌和大肠杆菌可能增加产品腐败的风险,影响产品的货架期。本研究结合多个技术全面评价婴幼儿配方奶粉的微生物污染情况,初步建立婴幼儿配方奶粉的微生物检测技术。

Biomonitoring for traditional herbal medicinal products using DNA metabarcoding and single molecule, real-time sequencing

Global concerns have been paid to the potential hazard of traditional herbal medicinal products(THMPs). Substandard and counterfeit THMPs, including traditional Chinese patent medicine, health foods, dietary supplements, etc. are potential threats to public health. Recent marketplace studies using DNA barcoding have determined that the current quality control methods are not sufficient for ensuring the presence of authentic herbal ingredients and detection of contaminants/adulterants. An efficient biomonitoring method for THMPs is of great needed. Herein, metabarcoding and single-molecule, realtime(SMRT) sequencing were used to detect the multiple ingredients in Jiuwei Qianghuo Wan(JWQHW), a classical herbal prescription widely used in China for the last 800 years. Reference experimental mixtures and commercial JWQHW products from the marketplace were used to confirm the method. Successful SMRT sequencing results recovered 5416 and 4342 circular-consensus sequencing(CCS) reads belonging to the ITS2 and psb A-trn H regions. The results suggest that with the combination of metabarcoding and SMRT sequencing, it is repeatable, reliable, and sensitive enough to detect species in the THMPs, and the error in SMRT sequencing did not affect the ability to identify multiple prescribed species and several adulterants/contaminants. It has the potential for becoming a valuable tool for the biomonitoring of multi-ingredient THMPs.

采用SMRT测序技术考察莲子的真菌群落多样性

目的 考察莲子中真菌群落的多样性。方法 采用单分子实时(SMRT)测序技术对莲子(红莲和白莲)中真菌的ITS全长扩增片段进行测序分析。通过评估测序数据、分析其α和β多样性,剖析真菌的组成、考察组间差异及菌属间的相关关系,剖析莲子的真菌群落结构。结果 共检测到1界、10门、30纲、75目、158科、247属和342种真菌,优势菌为Botryosphaeria wangensis(0~79.57%)、Lasiodiplodia laeliocattleyae(0.32%~49.18%)和Colletotrichum aenigma(0~31.76%)和Wallemia canadensis(0~22.86%)。有潜在致病风险的真菌为Colletotrichum aenigma、Aspergillus vitricola、Rhizomucor pusillus,存在产毒风险的真菌为Fusarium pernambucanum。红莲和白莲样品的真菌组成在组间存在显著性差异,差异菌主要是Botryosphaeria wangensis和Wallemia canadensis。结论 SMRT测序技术对研究莲子中真菌的多样性具有较好的适用性,并可通过分析产毒真菌的种类为莲子的安全使用提供风险预警。

九里香全长转录组测序分析

目的:获得九里香Murraya exotica L.Mant.全长转录组数据库,为深入挖掘其全长基因信息提供参考。方法:利用Pacino Sequel平台的第三代测序技术,对九里香的根、茎、叶、花、果混合样品进行全长转录组测序,并对原始转录组数据进行分析。结果:共获得94435个转录本,平均长度为76476.23 bp,80583条环形一致性序列,通过聚类、校正和去冗余后最终得到108443个高质量的isoforms,其中在非冗余蛋白(NR)、核苷酸序列(NT)、基因本体(GO)、真核生物相邻类的聚簇(KOG)、蛋白家族(Pfam)、京都基因与基因组百科全书(KEGG)和SwissProt共注释了100219个isoforms,同时检测出34182个简单序列重复(SSR)位点,其中18482个单核苷酸数量占主导位置;检测了2574个转录因子,29592个长链非编码RNAs(lncRNAs)和30322个mRNAs。结论:获得了较为可靠的九里香全长转录组数据,为深入研究九里香的生长发育、相关代谢途径、功能基因利用、基原物种鉴定等提供数据参考。

Comprehensive analysis of the full-length transcripts and alternative splicing involved in clubroot resistance in Chinese cabbage

Chinese cabbage is an economically important Brassica vegetable worldwide, and clubroot, which is caused by the soilborne protist plant pathogen Plasmodiophora brassicae is regarded as a destructive disease to Brassica crops. Previous studies on the gene transcripts related to Chinese cabbage resistance to clubroot mainly employed RNA-seq technology,although it cannot provide accurate transcript assembly and structural information. In this study, PacBio RS II SMRT sequencing was used to generate full-length transcriptomes of mixed roots at 0, 2, 5, 8, 13, and 22 days after P. brassicae infection in the clubroot-resistant line DH40R. Overall, 39 376 high-quality isoforms and 26 270 open reading frames(ORFs) were identified from the SMRT sequencing data. Additionally, 426 annotated long noncoding RNAs(lncRNAs),56 transcription factor(TF) families, 1 883 genes with poly(A) sites and 1 691 alternative splicing(AS) events were identified. Furthermore, 1 201 of the genes had at least one AS event in DH40R. A comparison with RNA-seq data revealed six differentially expressed AS genes(one for disease resistance and five for defensive response) that are potentially involved in P. brassicae resistance. The results of this study provide valuable resources for basic research on clubroot resistance in Chinese cabbage.

Integrative SMRT sequencing and ginsenoside profiling analysis provide insights into the biosynthesis of ginsenoside in Panax quinquefolium

Panax quinquefolium is one of the most common medicinal plants worldwide.Ginsenosides are the major pharmaceutical components in P.quinquefolium.The biosynthesis of ginsenosides in different tissues of P.quinquefolium remained largely unknown.In the current study,an integrative method of transcriptome and metabolome analysis was used to elucidate the ginsenosides biosynthesis pathways in different tissues of P.quinquefolium.Herein,22 ginsenosides in roots,leaves,and flower buds showed uneven distribution patterns.A comprehensive P.quinquefolium transcriptome was generated through single molecular real-time(SMRT)and second-generation sequencing(NGS)technologies,which revealed the ginsenoside pathway genes and UDP-glycosyltransferases(UGT)family genes explicitly expressed in roots,leaves,and flower buds.The weighted gene co-expression network analysis(WGCNA)of ginsenoside biosynthesis genes,UGT genes and ginsenoside contents indicated that three UGT genes were positively correlated to pseudoginsenoside F11,notoginsenoside R1,notoginsenoside R2 and pseudoginsenoside RT5.These results provide insights into ginsenoside biosynthesis in different tissues ofP.quinquefolium.

The role of small non-coding RNAs(sncRNAs)in male infertility:A scoping review

Objective:To give a brief overview of the field of epigenetics and the potential predictive power that small non-coding RNA(sncRNA)may hold in relation to improving the treatment and diagnosis of male infertility.Methods:PRISMA-ScR was used as the scoping review guideline for this investigation.All article data here have been accessed from MEDLINE–PubMed,Science Direct,EBSCO,Scopus,Sage Journals,and Google Scholar.The terms"small non coding RNA,male,infertility,miRNA,sperm"were used in the search between 2015 and 2023.Results:The study comprised 35 publications in total.Several sncRNAs,miR-155,miR-16,miR-196,miR-525-3p,miR-891 were found to be effective in regulating the mechanism of spermatozoa processing in the infertility of men.sncRNA can be used as a biomarker of male infertility.Conclusions:sncRNAs can act as biomarkers for the diagnosis of reproductive diseases.Actually,by recognizing sncRNAs and their mechanisms,a new way to treat infertile men would be paved.The functional annotation of sncRNAs in spermatogenesis is still in its infancy but has enormous potential.This is despite the fact that many potential sncRNAs have been found to date with the use of cutting-edge technology and publicly accessible sncRNA annotation tools.

Quantitative assessment of hematopoietic chimerism by quantitative real-time polymerase chain reaction of sequence polymorphism systems after hematopoietic stem cell transplantation

Background Analysis of changes in recipient and donor hematopoietic cell origin is extremely useful to monitor the effect of hematopoietic stem cell transplantation （HSCT） and sequential adoptive immunotherapy by donor lymphocyte infusions. We developed a sensitive, reliable and rapid real-time PCR method based on sequence polymorphism systems to quantitatively assess the hematopoietic chimerism after HSCT. Methods A panel of 29 selected sequence polymorphism （SP） markers was screened by real-time PCR in 101 HSCT patients with leukemia and other hematological diseases. The chimerism kinetics of bone marrow samples of 8 HSCT patients in remission and relapse situations were followed longitudinally. Results Recipient genotype discrimination was possible in 97.0% （98 of 101） with a mean number of 2.5 （1-7） informative markers per recipient/donor pair. Using serial dilutions of plasmids containing specific SP markers, the linear correlation （r） of 0.99, the slope between -3.2 and -3.7 and the sensitivity of 0.1% were proved reproducible. By this method, it was possible to very accurately detect autologous signals in the range from 0.1% to 30%. The accuracy of the method in the very important range of autologous signals below 5% was extraordinarily high （standard deviation 〈1.85%） which might significantly improve detection accuracy of changes in autologous signals early in the post-transplantation course of follow-up. The main advantage of the real-time PCR method over short tandem repeat PCR chimerism assays is the absence of PCR competition and plateau biases, with demonstrated greater sensitivity and linearity. Finally, we prospectively analyzed bone marrow samples of 8 patients who received allografts and presented the chimerism kinetics of remission and relapse situations that illustrated the sensitivity level and the promising clinical application of this method. Conclusion This SP-based real-time PCR assay provides a rapid, sensitive, and accurate quantitative assessment of mixed chimerism that can be useful in predicting graft rejection and early relapse.