ABSTRACT
Objective To prepare quality control samples for St.Louis encephalitis virus(SLEV)molecular detection by constructing pseudovirus containing target sequences of SLEV.Methods According to the principles of armored RNA technique, the prM gene sequence of SLEV was cloned into the prokaryotic expression vector to generate recombinant plasmid pSE380-MS2-SLEV.Then, recombinant E.coli transformed with the corresponding plasmid was induced with IPTG to produce recombinant pseudovirus particles.The particles were purified by chloroform and further characterized by double enzyme digestion and transmission electron microscopy.The temperature sensitivity experiments and quantitative RT-PCR were performed to validate the potential of these pseudovirus particles as quality control samples.Results PCR amplification and sequencing analysis confirmed that the prM gene sequence of SLEV was cloned into vector pSE380-MS2.Transmission electron microscopy showed that homogenous spherical particles with a diameter of about 25 nm were produced upon IPTG induction.The SLEV genomic RNA within the pseudovirus particles was resistant to DNaseⅠand RNase A digestion, and remained stable for 20 days at 37℃.These samples were validated with quantitative RT-PCR for SLEV.Conclusion The RNase-resistant and stable pseudovirus particles containing prM fragment of SLEV are constructed successfully, which can be used as positive quality control samples for RNA extraction and molecular detection.
ABSTRACT
Enterovirus 71 (EV71) is one of the primary causative agents of hand, foot and mouth disease in children and closely associated with severe neurological complications and even deaths.EV71 outbreaks have occurred throughout the Asia-Pacific region since 1990s, posing global public health threat;however, no specific therapeutic strategy exists for severe EV71 infection.Several inactivated vaccine products have entered or finished the clinical trial stage, and some novel vaccine candidates, including live attenuated, subunit, and virus-like particle, show great potential for further develop-ment.This review summarizes the present situation and progress in the development of EV71 vaccines.
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Beijing has been one of the epicenters attacked most severely by the SARS-CoV (severe acute respiratory syndrome-associated coronavirus) since the first patient was diagnosed in one of the city's hospitals. We now report complete genome sequences of the BJ Group, including four isolates (Isolates BJ01, BJ02, BJ03, and BJ04) of the SARS-CoV. It is remarkable that all members of the BJ Group share a common haplotype, consisting of seven loci that differentiate the group from other isolates published to date. Among 42 substitutions uniquely identified from the BJ group, 32 are non-synonymous changes at the amino acid level. Rooted phylogenetic trees, proposed on the basis of haplotypes and other sequence variations of SARS-CoV isolates from Canada, USA, Singapore, and China, gave rise to different paradigms but positioned the BJ Group, together with the newly discovered GD01 (GD-Ins29) in the same clade, followed by the H-U Group (from Hong Kong to USA) and the H-T Group (from Hong Kong to Toronto), leaving the SP Group (Singapore) more distant. This result appears to suggest a possible transmission path from Guangdong to Beijing/Hong Kong, then to other countries and regions.
Subject(s)
Humans , Genome, Viral , Haplotypes , Mutation , Open Reading Frames , Phylogeny , Severe acute respiratory syndrome-related coronavirus , GeneticsABSTRACT
Much attention has been paid to photocatalytic oxidation in the field of air and water purification. Photocatalytic oxidation employs semiconductors such as TiO2, ZnO as a photocatalyst in ultraviolet radiation. Several factors which affect photocatalytic decomposition were discussed in the present paper. Photocatalytic oxidation technique is applicable for the elimination of gas-phase contamination in air.