Attenuation of mouse hepatitis virus by deletion of the LLRKxGxKG region of Nsp1.

Coronaviruses are a family of large positive-sense RNA viruses that are responsible for a wide range of important veterinary and human diseases. Nsp1 has been shown to have an important role in the pathogenetic mechanisms of coronaviruses in vivo. To assess the function of a relatively conserved domain (LLRKxGxKG) of MHV nsp1, a mutant virus, MHV-nsp1-27D, with a 27 nts (LLRKxGxKG) deletion in nsp1, was constructed using a reverse genetic system with a vaccinia virus vector. The mutant virus had similar growth kinetics to MHV-A59 wild-type virus in 17CI-1 cells, but was highly attenuated in vivo. Moreover, the mutant virus completely protected C57BL/6 mice from a lethal MHV-A59 challenge. To further analyze the mechanism of the attenuation of the mutant virus, changes in reporter gene expression were measured in nsp1- or nsp1-27D-expressing cells; the results showed that nsp1 inhibited reporter gene expression controlled by different promoters, but that this inhibition was reduced for nsp1-27D. The research in vivo and in vitro suggests that the LLRKxGxKG region of nsp1 may play an important role in this process.

Studying the pathogenicity of TBEV to human neuroblastoma tumor cells / 中华微生物学和免疫学杂志

Objective To identify the infection and the replication of Tick-borne encephalitis virus(TBEV) in human neuroblastoma cells.Methods After being inffected with TBEV,the cell culture supernatant of human neuroblastoma cell line SK-N-SH was collected and assayed at different time points.Byusing real-time RT-PCR and plaque assay to measure the titer of virus in the supernatant,the replication andproliferation of TBEV in human neuroblastoma cell was identified.Meanwhile,the morphological change of SK-N-SH after TBEV infection was also visualized by observation under microscope and immunmquorescenceassay.Results Real-time RT-PCR and plaque assay both demonstrated that TBEV could replicate effectively in SK-N-SH cells,the peak titer could reach 2.92× 107 PFU/ml on 3 days post-inoculation.And significant morphological change occured on infected SK-N-SH cells after 2 days post inoculation.By immunofluorescence assay,the virus particles could be detected and visualized.Conclusion TBEV can replicate andproliferate effcctively and cause significant cell morphological changes in human neuroblastoma cell SK-N-SH,which demonstrated that SK-N-SH could be a suitable cell model for TBEV culture.

Construction and Genetic Analysis of Murine Hepatitis Virus Strain A59 Nsp16 Temperature Sensitive Mutant and the Revertant Virus / 中国病毒学·英文版

Coronaviruses (CoVs) are generally associated with respiratory and enteric infections and have long been recognized as important pathogens of livestock and companion animals. Mouse hepatitis virus (MHV) is a widely studied model system for Coronavirus replication and pathogenesis. In this study, we created a MHV-A59 temperature sensitive (ts) mutant Wu"-ts18(cd) using the recombinant vaccinia reverse genetics system. Virus replication assay in 17C1-1 cells showed the plaque phenotype and replication characterization of constructed Wu"-ts18(cd) were indistinguishable from the reported ts mutant Wu"-ts 18. Then we cultured the ts mutant Wu"-ts 18(cd) at non-permissive temperature 39.5℃, which "forced" the ts recombinant virus to use second-site mutation to revert from a ts to a non-ts phenotype. Sequence analysis showed most of the revertants had the same single amino acid mutation at Nsp16 position 43. The single amino acid mutation at Nsp16 position 76 or position 130 could also revert the ts mutant Wu"-ts 18 (cd) to non-ts phenotype, an additional independent mutation in Nsp13 position 115 played an important role on plaque size. The results provided us with genetic information on the functional determinants of Nsp16. This allowed us to build up a more reasonable model of CoVs replication-transcription complex.

Development of antibody-array for detection of six arboviruses / 中华微生物学和免疫学杂志

ObjectiveTo develop an antibody-array system for multiple detection of antibodies against Japanese B encephalitis virus (JEV),Tick-borne encephalitis virus (TBV),Dengue virus ( DENV ),West Nile virus (WNV),Western equine encephalitis virus (WEEV) and East Equine encephalitis virus (EEEV).MethodsRecombined antigens were spotted on array as capture antigens.Specific antibodies were detected by using a sandwich ELISA format.Rabbit antiserum was employed to select and confirm the specificity of antigens and to optimize the conditions of the assay.The detection efficiency of the system was validated by 40 clinical suspected serum samples and compared with the relative ELISA assays.ResultsEleven recombined antigens were selected as diagnostic antigens with high specificity.Better detection could be achieved when scale of antigen concentrations were within 0.125-0.900 mg/ml and the serum dilutions were 1:100-1:1000.When detecting the 26 clinical suspected TBE serum samples,20 were IgG positive (76.9％),and 17 were IgM positive (65.3％) which was 96.1％ and 84.6％ consistent with the relevant ELLSA tests,the 8 clinical suspected JEV serum samples,4 were IgG positive (50.0％),and 5 were IgM positive (62.0％),which was 86.3％ and 90.1％ consistent with the relevant ELLSA tests.As for the 22 DEN serum samples,13 were IgG positive (60％) and 15 were IgM positive (68％) which was 85％ and 93％ consistent with ELISA.The specificity of the assay was 100％ and the sensitivity was higher than the relative ELISAs.ConclusionThe developed antibody-array is highly specific and reliable,which could be used for the detection of antibodies against the 6 arboviruses.

The application of monoclonal antibody 2A10 on protein chip for detecting of Flavivirus / 中华微生物学和免疫学杂志

Objective To evaluate the Flavivirus specific monoclonal antibody(McAb) 2A10 as detective antibody for simultaneously identify tick borne encephalitis virus( TBEV), Japanese encephalitis virus( JEV), dengue ( DEN )-2, DEN-4 and yellow fever virus ( YFV ) by antibody microarray technique.Methods The antibody microarray was developed by spotting TBEV, JEV, DEN-2, DEN-4 and YFV specific McAb on chip as capture antibodies. After incubating with cultured viral supernatants of the above viruses, CY3 labeled detective antibody 2A10 was added to the chips. After reaction, the antibody microarray was scanned and the results were analyzed. By comparing the signal intensities of different spots on chips,the detecting titre and sensitivity of 2A10 for Flavivirus were determined, and the value of 2A10 in detection of Flavivirus was evaluated. Results The hybridization results demonstrated that the titre of 2A10 for Flavi2A10 was specific for Flavivirus and could be used as universal detective antibody for Flavivirus on antibody microarray.

A genome sequence of novel SARS-CoV isolates: the genotype, GD-Ins29, leads to a hypothesis of viral transmission in South China / 基因组蛋白质组与生物信息学报·英文版

We report a complete genomic sequence of rare isolates (minor genotype) of the SARS-CoV from SARS patients in Guangdong, China, where the first few cases emerged. The most striking discovery from the isolate is an extra 29-nucleotide sequence located at the nucleotide positions between 27,863 and 27,864 (referred to the complete sequence of BJ01) within an overlapped region composed of BGI-PUP5 (BGI-postulated uncharacterized protein 5) and BGI-PUP6 upstream of the N (nucleocapsid) protein. The discovery of this minor genotype, GD-Ins29, suggests a significant genetic event and differentiates it from the previously reported genotype, the dominant form among all sequenced SARS-CoV isolates. A 17-nt segment of this extra sequence is identical to a segment of the same size in two human mRNA sequences that may interfere with viral replication and transcription in the cytosol of the infected cells. It provides a new avenue for the exploration of the virus-host interaction in viral evolution, host pathogenesis, and vaccine development.

STUDY ON THE ASSOCIATION BETWEEN A NOVEL CORONAVIRUS AND THE SARS PATHOGEN / 解放军医学杂志

Objective To determine the causative association between a newly isolated coronavirus and the current epidemic of severe acute respiratory syndrome (SARS) Methods Coronavirus was isolated from the samples of patients with SARS by cell culture Immunofluorescence assay and neutralization test were used to detect the antibodies in serum of SARS patients against newly isolated coronavirus, in order to analyze and determine the association between coronavirus and SARS pathogen Results The antibodies against the novel coronavirus could be detected in 99 of 113 sera from clinically diagnosed SARS patients The results of 10 pairs of double serum detection showed that, antibody titers in the late phase were significantly higher than those in the acute phase, and a highest increase by 128 folds was being found. The neutralization test showed that the antibodies from SARS patients' sera could neutralize the novel coronavirus Conclusion The newly isolated coronavirus was closely associated with and possibly the key pathogen of SARS