Virus Reverse Transcriptase-polymerase Chain Reaction Research Articles

Design and Evaluation of the Primers for Rift Valley Fever (RVF) Virus RT-PCR Detection

Rift Valley Fever (RVF) is a notifiable multiple species diseases in the OIE list, and causes human and agricultural losses in endemic regions. To develop the rapid method for detecting of RVF, 2 specific primers for reverse transcriptase polymerase chain reaction (RT-PCR) and 7 overlapping oligo primers were designed according to the nucleotide sequence information of RVFV published in GenBank, and a DNA fragment about 318 bp of the segment S was synthesized in vitro by overlap extension PCR to construct the recombinant plasmid pMD19-T-RVFVS. Then, the 2 specific primers were evaluated via a serial of tests, including reaction temperature optimization test, sensitivity and specificity tests. The results showed that the 2 designed primers are suitable for RVFV RT-PCR detection which is a rapid method with good specificity and sensitivity, the detection limit was approximately 85 copies of the cloned viral genomic fragments (pMD19-T-RVFVS) as well as resulted in no cross-reaction for peste des petits ruminants virus (PPRV), Epidemic encephalitis B virus, E.coli , Salmonella and Pasteurella multocida etc common pathogens isolated from ruminants detection.

Detection of human viral RNA via a combined fluorescence and SERS molecular beacon assay.

A dual-mode molecular beacon on a multiplexed substrate has been developed and applied to the measurement of unlabeled human viral RNA. The detection system is based on a combined surface-enhanced Raman scattering (SERS) and fluorescent molecular beacon assay that is assembled on Nanobarcodes™ particles. In this assay, a molecular beacon probe terminated with a fluorescent Raman label dye is conjugated to the metallic Nanobarcodes™ particles. The molecular beacon probe is a single-stranded oligonucleotide that has been designed with a hairpin structure that holds the dye at 3′-end close to the particle surface when the probe is attached through a 5′-thiol group. In this configuration, the SERS spectrum of the label was obtained and its fluorescence quenched because the dye is in very close proximity to a noble metal surface with nanoscale features (Nanobarcodes™ particles). The SERS signal decreased and the fluorescence signal increased when target viral RNA was captured by this molecular beacon probe. In addition, a hepatitis C virus reverse transcriptase-polymerase chain reaction (HCV RT-PCR) product was detected using this dual-mode beacon. The development of a multiplexed, label-free assay system with the reassurance offered by detection of two distinctly separate signals offers significant benefits for rapid molecular diagnostics.

Lassa Fever, Nigeria, 2003 and 2004

Lassa Fever, Nigeria, 2003 and 2004

Nictitating Membrane as a Potentially Useful Postmortem Diagnostic Specimen for Classical Swine Fever

The gold standard for diagnosis of classical swine fever (CSF) is cell culture virus isolation combined with reverse transcriptase-polymerase chain reaction (RT-PCR) and fluorescent antibody test (FAT) in cryosections of tonsils, spleen, various lymph nodes, ileum, and kidney. Autolytic and heterolytic samples render correct FAT evaluation difficult and can even yield false-negative or ambiguously positive results. To extend the spectrum of CSF diagnostic specimens, the authors tested whether the nictitating membrane (NM) might be a useful adjunct diagnostic specimen in wild boars and domestic pigs. To accomplish this, results of virus isolation, FAT, and RT-PCR were compared on NM samples and lymphoid tissues, which are the routine specimens of choice for CSF diagnosis. Wild boars (n = 30) and domestic pigs (n = 8) were experimentally challenged with various CSF virus (CSFV) strains or isolates of different virulence. The FAT revealed CSFV antigen in surface and tubular adenoid epithelium as well as in lymphatic follicles of the NM. In wild boars and domestic pigs with CSF, a strong agreement was found between results of FAT, virus isolation, and RT-PCR on NM and lymphoid tissues. These results suggest that NM is a useful additional specimen that can provide valuable data for postmortem diagnosis of CSF. The NM is relatively easy to sample at necropsy, and postmortem autolysis and heterolysis of this tissue is minimal compared with internal organs.

Osteoprogenitor Cells and Osteoblasts Are Targets for Hepatitis C Virus

The goal of this study was to determine whether human osteoblasts might harbor the hepatitis C virus. We tested for positive-strand and negative-strand (replicative) hepatitis C virus RNA by reverse transcriptase-polymerase chain reaction, by in situ reverse transcriptase-polymerase chain reaction for intracellular localization of the hepatitis C virus, and by amplicon sequencing in in vitro differentiated mature osteoblasts from STRO-1+ osteoprogenitor cells from patients with chronic hepatitis C and from healthy individuals. We only detected the hepatitis C virus genome in STRO-1+ cells and mature osteoblasts from carriers with chronic hepatitis C, and we found hepatitis C virus negative strands expressed sporadically in these patients. Using in situ hepatitis C virus reverse transcriptase-polymerase chain reaction, we determined that the percentage of infected carrier osteoblasts ranged from 8.0-15.3%. These data provide evidence of hepatitis C virus presence and replication in human osteoprogenitors and osteoblasts, which may have important implications for bone allograft processing.

A novel nested PCR for the diagnosis of calicivirus infections in the cat

A novel nested PCR (nPCR) assay is reported on the diagnosis of the feline calicivirus (FCV) infection. The test was performed on 47 ocular and 40 pharyngeal swabs collected from 47 cats with respiratory syndrome; among the 87 samples examined, 18 ocular and 23 pharyngeal swabs were positive in nPCR. The nPCR sensitivity was compared to other diagnostic techniques such as virus isolation on cell culture and reverse transcriptase-polymerase chain reaction (RT-PCR). The nPCR was more sensitive than the virus isolation and RT-PCR; therefore, it can be used for calicivirosis diagnosis in cats.

Gene-array analysis of glioma cells after treatment with an anti-PKCalpha siRNA: a general protocol.

Post-transcriptional gene silencing is a powerful tool to reveal gene function. In this chapter, we have used gene-array technology to analyze changes in gene expression after specific targeting of the protein kinase Calpha isoform with small interfering RNAs (siRNAs). Expression profiles were investigated on a human gene array of 588 key genes involved in DNA synthesis, apoptosis, cell-cell communication, intracellular signal-transduction pathways, cell-surface molecules and transcription factors. The data indicate that siRNAs are an ideal tool for target validation, and show that RNA-dependent RNA polymerase is not required for RNAi in mammalian cells.