通讯机构：
[Lu, Fangguo] U;[Hu, J; Lu, FG] H;Hunan Univ Chinese Med, Dept Microbiol, Sch Med, Changsha 410208, Hunan, Peoples R China.;Univ Innovat Team Hunan Prov, Key Discipline Pathogen Biol, Changsha 410208, Hunan, Peoples R China.
关键词：
*16S rRNA;*Carboxyfluorescein;*DNA probe;*DNA/RNA hybrids;*Drug-resistant bacteria;*Enzymatic reaction;*Fluorescence resonance energy transfer;*Fluorometry;*Quenching
摘要：
The authors describe a method for the fluorometric determination of methicillin-resistant Staphylococcus aureus (MRSA) by exploiting target-triggered chain reactions and deoxyribonuclease I (DNase I)-aided target recycling. It is making use of a carboxy-fluorescein (FAM)-labeled single-stranded probe containing two sections. One is complementary to the 5' terminus of the target, while the 3' terminus of the other target is adsorbed on the surface of graphene oxide (GO) via pi-stacking interactions without the target (16S rRNA). This adsorption results in quenching of the fluorescence of the label and protects it from being cleaved by DNase I. However, upon addition of the target, DNA/RNA hybrids are repelled by GO. This leads to fluorescence recovery as measured at excitation/emission wavelengths of 480/514 nm due to a chain reaction that is triggered by the target. The signal is strongly amplified by using DNase I-mediated target recycling. The 16S rRNA of MRSA can be detected by this method in the 1 to 30 nM concentration range, and the detection limit is 0.02 nM. The method was applied to analyze bacterial samples, and the detection limit is as low as 30 CFU . mL(-1). The assay is highly sensitive and selective and in our percpetion has a large potential in diagnosis of drug-resistant bacteria. Graphical abstract Schematic of the graphene oxide-based fluorescent bioassay for Methicillin-resistant Staphylococcus aureus detection by using target-triggered chain reaction and deoxyribonuclease I-aided signal amplification.
摘要：
The 2009 H1N1 influenza (Pdm09) pandemic has been referred to as the first influenza pandemic of the twenty-first century. There is a marked difference in antigenicity between the pandemic H1N1 virus and past seasonal H1N1 viruses, which allowed the pandemic virus to spread rapidly in humans. Antibodies (Abs) against hemagglutinin (HA), especially neutralizing Abs against epitopes in the head of HA, play critical roles in defending the host against the virus. Some preexisting neutralizing Abs that recognize neutralizing epitopes of Pdm09 HA, thereby affording cross-protection, have been reported. To better understand the protective effects of epitopes in Pdm09 HA, we constructed a series of plasmid DNAs (DNA vaccines) by cloning various combinations of Pdm09 neutralizing epitopes into the HA backbone derived from A/PR/8/1934 (H1N1). We subsequently compared the protective immune responses induced by these various forms of HA in a mouse model. We found that the plasmid DNAs with epitope substitutions provided better protection against lethal virus challenge and induced higher strain-specific antibody titers, with epitope Sa being the most effective. Moreover, the combination of epitopes Sa and Sb provided almost complete protection in mice. These findings provide new insights into the protective efficacy of neutralizing epitopes of influenza HA.
作者机构：
[Fang, Fang; Zhang, Fenghua; Peng, Bo; Fang, F; Chen, Ze; Chang, Haiyan] Hunan Normal Univ, Coll Life Sci, Changsha, Hunan, Peoples R China.;[Zhang, Ran] Hunan Normal Univ, Sch Med, Changsha, Hunan, Peoples R China.;[Lu, Fangguo] Hunan Univ Chinese Med, Sch Med, Changsha, Hunan, Peoples R China.;[Wang, Fuyan] Cent S Univ, Dept Immunol, Coll Basic Med Sci, Changsha, Hunan, Peoples R China.;[Chen, Ze] Shanghai Inst Biol Prod, Shanghai, Peoples R China.
通讯机构：
[Fang, F; Chen, Z] H;[Chen, Ze] S;Hunan Normal Univ, Coll Life Sci, Changsha, Hunan, Peoples R China.;Shanghai Inst Biol Prod, Shanghai, Peoples R China.
关键词：
Vaccines;Influenza;Enzyme-linked immunoassays;Immune response;H5N1;Viral vaccines;Vaccination and immunization;Influenza viruses
摘要：
Maternally-derived antibodies (MDAs) can protect offspring against influenza virus infection but may also inhibit active immune responses. To overcome MDA- mediated inhibition, active immunization of offspring with an inactivated H5N1 whole-virion vaccine under the influence of MDAs was explored in mice. Female mice were vaccinated twice via the intraperitoneal (IP) or intranasal (IN) route with the vaccine prior to mating. One week after birth, the offspring were immunized twice via the IP or IN route with the same vaccine and then challenged with a lethal dose of a highly homologous virus strain. The results showed that, no matter which immunization route (IP or IN) was used for mothers, the presence of MDAs severely interfered with the active immune response of the offspring when the offspring were immunized via the IP route. Only via the IN immunization route did the offspring overcome the MDA interference. These results suggest that intranasal immunization could be a suitable inoculation route for offspring to overcome MDA interference in the defense against highly pathogenic H5N1 virus infection. This study may provide references for human and animal vaccination to overcome MDA-induced inhibition.
摘要：
Two new anthraquinones, 1,3-dihydroxy-5-methoxy-6-methoxymethyl-2-methyl-9,10-anthraquinone (1) and 1,3-dihydroxy-5-methoxy-2,6-bismethoxymethyl-9,10-anthraquinone (2), together with ten known anthraquinone derivatives (3-12), three coumarin derivatives (13-15), and 6-gingerol (16) were isolated from the barks of Morinda citrifolia (Noni) collected in the Yongxing island of Xisha. The structures of compounds (1-16) were determined on the basis of extensive spectroscopic analyses, as well as by comparison with literature reports. The new compounds 1 and 2 were tested for their antiviral, cytotoxic, and antibacterial activities. In the primary bioassays, compounds 1 and 2 displayed weak antiH1N1 activity with IC50 values of 66.1 and 10.5 mu M, respectively. In addition, compound 2 showed weak anti-H3N2 activity with IC50 value of 11.5 mu M, and had weak antimicrobial activity against Staphylococcus aureus with MIC value of 24.5 mu M. (C) 2015 Phytochemical Society of Europe. Published by Elsevier B.V. All rights reserved.
