[Show abstract][Hide abstract] ABSTRACT: RNA interference (RNAi) is a powerful tool to silence gene expression. Small interfering RNA (siRNA)-induced RNA degradation has been recently used as an antivirus agent to inhibit specific virus replication. Here, we showed that several siRNAs specific for conserved regions of influenza virus matrix (M2) and nucleocapsid protein (NP) genes could effectively inhibit expression of the corresponding viral protein. We also evaluated the antiviral potential of these siRNAs targeting M2 and NP of H5N1 avian influenza virus (AIV), which are essential to viral replication. We investigated the inhibitory effect of M2-specific siRNAs and NP-specific siRNAs on influenza A virus (H5N1, H1N1 and H9N2) replication in Madin-Darby canine kidney (MDCK) cells and BALB/c mice. The results showed that treatment with these siRNAs could specifically inhibit influenza A virus replication in MDCK cells (0.51-1.63 TCID(50) reduction in virus titers), and delivery of pS-M48 and pS-NP1383 significantly reduced lung virus titers in the infected mice (16-50-fold reduction in lung virus titers) and partially protected the mice from lethal influenza virus challenge (a survival rate of 4/8 for H1N1 virus-infected mice and 2/8 for H5N1 virus infected mice). Moreover, the treatment of pS-M48 and pS-NP1383 could suppress replication of different subtypes of influenza A viruses, including a H5N1 highly pathogenic avian isolate strain. The results provided a basis for further development of siRNA for prophylaxis and therapy of influenza virus infection in humans and animals.
Full-text · Article · Dec 2007 · Antiviral Research
[Show abstract][Hide abstract] ABSTRACT: In 2004, 3 and 4 strains of avian influenza virus (subtype H5N1) were isolated from waterfowl and chickens, respectively, in central People's Republic of China. Viral replication and pathogenicity were evaluated in chickens, quails, pigeons, and mice. We analyzed the sequences of the hemagglutinin and neuraminidase genes of the isolates and found broad diversity among them.
Preview · Article · Jun 2007 · Emerging infectious diseases
[Show abstract][Hide abstract] ABSTRACT: A latex agglutination test (LAT) was developed for rapid detection of antibodies to H5 avian influenza viruses (AIVs). The hemagglutinin protein of H5 AIV was covalently linked to carboxylated latex by ethyl-dimethyl-amino-propyl carbodiimide to prepare the sensitized latex beads. The LAT was evaluated with the hemagglutination inhibition (HI) assay as the reference test. The H5-LAT showed a sensitivity of 87.0% and specificity of 88.9% in detecting 126 serum samples from experimentally infected chickens and a sensitivity of 82.5% and specificity of 86% in detecting 587 field chicken serum samples from mostly vaccinated chickens. The agreement ratio between H5-LAT and HI was found to be 87.3% and 83.1% for the two groups of samples, respectively. Difficulty with background agglutination in stored chicken sera was overcome by serum pretreatment with either dried chicken liver powder or dilution buffer containing detergent Tween-20. The H5-LAT has advantages over a previously reported whole-virus LAT in terms of biosafety in preparation, chemical stability, and higher specificity. It is a rapid and simple test suitable for field monitoring of antibodies to H5-type AIV.