Comparison of amplicon-sequencing, pyrosequencing and real-time PCR for detection of YMDD mutants in patients with chronic hepatitis B

Detection of hemagglutinin variants of the pandemic influenza A (H1N1) 2009 virus by pyrosequencing

For influenza viruses, pyrosequencing has been successfully applied to the high-throughput detection of resistance markers in genes encoding the drug-targeted M2 protein and neuraminidase. In this study, we expanded the utility of this assay to the detection of multiple receptor binding variants of the hemagglutinin protein of influenza viruses directly in clinical specimens. Specifically, a customized pyrosequencing protocol that permits detection of virus variants with the D, G, N, or E amino acid at position 222 in the hemagglutinin of the 2009 pandemic influenza A (H1N1) virus was developed. This customized pyrosequencing protocol was applied to the analysis of 241 clinical specimens. The use of the optimized nucleotide dispensation order allowed detection of mixtures of variants in 10 samples (4.1%) which the standard cyclic nucleotide dispensation protocol failed to detect. The optimized pyrosequencing protocol is expected to provide a more accurate tool in the analysis of virus variant composition.

Metagenomic pyrosequencing and microbial identification

BACKGROUND

The Human Microbiome Project has ushered in a new era for human metagenomics and high-throughput next-generation sequencing strategies.

CONTENT

This review describes evolving strategies in metagenomics, with a special emphasis on the core technology of DNA pyrosequencing. The challenges of microbial identification in the context of microbial populations are discussed. The development of next-generation pyrosequencing strategies and the technical hurdles confronting these methodologies are addressed. Bioinformatics-related topics include taxonomic systems, sequence databases, sequence-alignment tools, and classifiers. DNA sequencing based on 16S rRNA genes or entire genomes is summarized with respect to potential pyrosequencing applications.

SUMMARY

Both the approach of 16S rDNA amplicon sequencing and the whole-genome sequencing approach may be useful for human metagenomics, and numerous bioinformatics tools are being deployed to tackle such vast amounts of microbiological sequence diversity. Metagenomics, or genetic studies of microbial communities, may ultimately contribute to a more comprehensive understanding of human health, disease susceptibilities, and the pathophysiology of infectious and immune-mediated diseases.

Identifications of pathogens - a bioinformatic point of view

Over the past 15 years, microbiology has undergone a momentous shift toward molecular methods. New sequences appear daily in the public databases and new computer tools and web servers are published on a regular basis. Major advances in molecular identifications of pathogens have been made because new biotechnology methods have appeared that often require a thorough in silico analysis of sequences. However, significant difficulties partly remain in developing efficient methods because the public databases contain many poorly annotated or partial sequences (often of environmental origin) and also because there are few dedicated web servers and curated databases.

Progress in the treatment of hepatitis B and digestive tumors with cantharidin and its analogues

Blister beetle or mylabris, pungent in flavor and toxic in nature, has been used for more than 2000 years as traditional Chinese medicine in China. Cantharidin, an active ingredient of the blister beetle, is an effective therapeutic agent against cancers of the liver, breast, esophagus, lung and intestine, etc. However, it is very toxic. Nocantharidin (NCTD), a derivative of cantharidin first synthesized in China, is a new anti-tumor drug with strong anti-tumor activities and increases the number of while blood cells. Cantharidin can be used in the treatment of hepatitis B and pointed condyloma. This paper reviews the progress in its clinical applications at home and abroad.

Comparison of ligase detection reaction and real-time PCR for detection of low abundant YMDD mutants in patients with chronic hepatitis B

AIM: To compare the ligase detection reaction (LDR) and real-time PCR for detection of low abundant YMDD mutants in patients with chronic hepatitis B infection.

METHODS: Mixtures of plasmids and serum samples from 52 chronic hepatitis B patients with low abundant lamivudine-resistant mutations were tested with LDR and real-time PCR. Time required and reagent cost for both assays were evaluated.

RESULTS: Real-time PCR detected 100, 50, 10, 1 and 0.1% of YIDD plasmid, whereas LDR detected 100, 50, 10, 1, 0.1, and 0.01% of YIDD plasmid, in mixtures with YMDD plasmid of 10⁶ copies/mL. Among the 52 clinical serum samples, completely concordant results were obtained for all samples by both assays, and 39 YIDD, 9 YVDD, and 4 YIDD/YVDD were detected. Cost and time required for LDR and real-time PCR are 60/80 CNY (8/10.7 US dollars) and 4.5/2.5 h, respectively.

CONCLUSION: LDR and real-time PCR are both sensitive and inexpensive methods for monitoring low abundant YMDD mutants during lamivudine therapy in patients with chronic hepatitis B. LDR is more sensitive and less expensive, while real-time PCR is more rapid.

DNA pyrosequencing-based bacterial pathogen identification in a pediatric hospital setting

Sole reliance on biochemical methods can limit the clinical microbiology laboratory's ability to identify bacterial pathogens. This study describes the incorporation of DNA pyrosequencing-based identification for routine pathogen identification of atypical clinical isolates in a large children's hospital. The assay capitalized on the highly conserved nature of 16S rRNA genes by positioning amplification and sequencing primers in conserved target sequences flanking the variable V1 and V3 regions. A total of 414 isolates of 312 pediatric patients were tested by DNA pyrosequencing during the time period from December 2003 to July 2006. Seventy-eight different genera were specified by DNA pyrosequencing, and isolates were derived from diverse specimen types. By integrating DNA sequencing of bacterial pathogens with conventional microbiologic methods, isolates that lacked a definitive identification by biochemical testing yielded genus- or species-level identifications in approximately 90% of cases by pyrosequencing. Improvements incorporated into the assay process during the period of clinical testing included software enhancements, improvements in sequencing reagents, and refinements in database search strategies. Coupled with isolation by bacteriologic culture and biochemical testing, DNA pyrosequencing-based bacterial identification was a valuable tool that markedly improved bacterial pathogen identification in a pediatric hospital setting.