Rapid detection of avian influenza virus a and subtype H5N1 by single step multiplex reverse transcription-polymerase chain reaction.
ABSTRACT Outbreaks of H5N1 highly pathogenic avian influenza (HPAI) virus caused great economic losses to the poultry industry and resulted in human deaths in Thailand and Viet Nam in 2004. Rapid typing and subtyping of H5N1 viruses, especially from clinical specimens, are desirable for taking prompt control measures to prevent the spread of the disease. Here, we developed a set of oligonucleotide primers able to detect, type and subtype H5 and N1 influenza viruses in a single step multiplex reverse transcription-polymerase chain reaction (RT-PCR). RNA was extracted from allantoic fluid or from specimens with guanidinium isothiocyanate reagent. Reverse transcription and PCR were carried out with a mixture of primers specific for influenza viruses of type A, subtype H5 and N1 in a single reaction system under identical conditions. The amplified DNA fragments were analyzed by agarose gel electrophoresis. All the H5N1 viruses tested in the study and the experimental specimens presented three specific bands by the method established here. The results presented here suggest that the method described below is rapid and specific and, therefore, could be valuable in the rapid detection of H5N1 influenza viruses in clinics.
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ABSTRACT: The H5N1 subtype of the highly pathogenic (HP) avian influenza virus has been recognized for its ability to cause serious pandemics among humans. In the present study, new monoclonal antibodies (mAbs) against viral proteins were established for the immunological detection of H5N1 influenza virus for research and diagnostic purposes. B-cell hybridomas were generated from mice that had been hyperimmunized with purified A/Vietnam/1194/2004 (NIBRG-14) virion that had been inactivated by UV-irradiation or formaldehyde. After screening over 4,000 hybridomas, eight H5N1-specific clones were selected. Six were specific for hemagglutinin (HA) and had in vitro neutralization activity. Of these, four were able to broadly detect all tested clades of the H5N1 strains. Five HA-specific mAbs detected denatured HA epitope(s) in Western blot analysis, and two detected HP influenza virus by immunofluorescence and immunohistochemistry. A highly sensitive antigen-capture sandwich ELISA system was established by combining mAbs with different specificities. In conclusion, these mAbs may be useful for rapid and specific diagnosis of H5N1 influenza. Therapeutically, they may have a role in antibody-based treatment of the disease.Japanese journal of infectious diseases 01/2012; 65(1):19-27. · 1.51 Impact Factor
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ABSTRACT: The appearance of eight new respiratory viruses, including the SARS coronavirus in 2003 and swine-origin influenza A/H1N1 in 2009, in the human population in the past nine years has tested the ability of virology laboratories to develop diagnostic tests to identify these viruses. Nucleic acid based amplification tests (NATs) for respiratory viruses were first introduced two decades ago and today are utilized for the detection of both conventional and emerging viruses. These tests are more sensitive than other diagnostic approaches, including virus isolation in cell culture, shell vial culture (SVC), antigen detection by direct fluorescent antibody (DFA) staining, and rapid enzyme immunoassay (EIA), and now form the backbone of clinical virology laboratory testing around the world. NATs not only provide fast, accurate and sensitive detection of respiratory viruses in clinical specimens but also have increased our understanding of the epidemiology of both new emerging viruses such as the pandemic H1N1 influenza virus of 2009, and conventional viruses such as the common cold viruses, including rhinovirus and coronavirus. Multiplex polymerase chain reaction (PCR) assays introduced in the last five years detect up to 19 different viruses in a single test. Several multiplex PCR tests are now commercially available and tests are working their way into clinical laboratories. The final chapter in the evolution of respiratory virus diagnostics has been the addition of allelic discrimination and detection of single nucleotide polymorphisms associated with antiviral resistance. These assays are now being multiplexed with primary detection and subtyping assays, especially in the case of influenza virus. These resistance assays, together with viral load assays, will enable clinical laboratories to provide physicians with new and important information for optimal treatment of respiratory virus infections.Critical Reviews in Clinical Laboratory Sciences 09/2011; 48(5-6):217-49. · 3.78 Impact Factor
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ABSTRACT: We have previously developed a software package called PrimerHunter to design primers for PCR-based virus subtyping. In this study, 9 pairs of primers were designed with PrimerHunter and successfully used to differentiate the 9 neuraminidase (NA) genes of avian influenza viruses (AIVs) in multiple PCR-based assays. Furthermore, primer pools were designed and successfully used to decrease the number of reactions needed for NA subtyping from 9 to 4. The quadruplicate primer-pool method is cost-saving, and was shown to be suitable for the NA subtyping of both cultured AIVs and uncultured AIV swab samples. The primers selected for this study showed excellent sensitivity and specificity in NA subtyping by RT-PCR, SYBR green-based Real-time PCR and Real-time RT-PCR methods. AIV RNA of 2 to 200 copies (varied by NA subtypes) could be detected by these reactions. No unspecific amplification was displayed when detecting RNAs of other avian infectious viruses such as Infectious bronchitis virus, Infectious bursal disease virus and Newcastle disease virus. In summary, this study introduced several sensitive and specific PCR-based assays for NA subtyping of AIVs and also validated again the effectiveness of the PrimerHunter tool for the design of subtyping primers.PLoS ONE 01/2013; 8(11):e81842. · 3.73 Impact Factor