Establishment and preliminary application of dengue virus envelope domain III IgG antibody capture enzyme-linked immuno-absorbent assay / 中华预防医学杂志

<p><b>OBJECTIVE</b>To establish a highly sensitive and specific assay to detect dengue virus (DENV) envelope protein domain III (EDIII) IgG antibody, and to explore its value in the diagnosis and seroepidemiological survey of dengue.</p><p><b>METHODS</b>The DENV EDIII IgG antibody capture ELISA was developed using the recombinant full-length DENV EDIII, which was prepared by Pichia yeast expression system as the capture antigen. The serum samples were collected from the same group of 35 DENV-1 patients of primary infection during disease period in 2006 and their follow-up phase in 2010; and the sensitivity of the assay was compared to that of the commercial Panbio DENV IgG ELISA.</p><p><b>RESULTS</b>The sensitivity of DENV EDIII IgG ELISA in detecting the serum samples from disease period and follow-up phase was 87% (20/23) and 94% (33/35), respectively; whereas the sensitivity of Panbio DENV IgG ELISA was 71% (25/35) and 0, respectively. The sensitivity of DENV EDIII IgG ELISA in detecting the serum samples from both periods was similar, without statistical significance (χ(2) = 0.946, P = 0.331). For serum samples from disease period, the sensitivity of DENV EDIII IgG ELISA was comparable with that of Panbio DENV IgG ELISA (χ(2) = 1.924, P = 0.165). However, DENV EDIII IgG ELISA demonstrated a significantly higher sensitivity than Panbio DENV IgG ELISA in detecting the serum samples from follow-up phase (χ(2) = 62.432, P = 0.000).</p><p><b>CONCLUSION</b>DENV EDIII IgG capture ELISA is highly sensitive in detecting IgG in the serum samples from either disease period or follow-up phase. This method might be a promising alternative for diagnosis and seroepidemiologic survey of dengue.</p>

Inhibitory effect of short hairpin RNA targeting survivin gene on human ectopic endometrial cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To construct a lentiviral expression vector for short hairpin RNA (shRNA) of human survivin gene, and assess its gene silencing effect in human ectopic endometrial cells.</p><p><b>METHODS</b>Human survivin gene shRNA sequence was designed using a software available on-line. The synthesized shRNA sequence was cloned into the pGCL-GFP vector to construct LV-survivin shRNA, which was confirmed by PCR and DNA sequence analysis. The packaging 293T cells were cotransfected with LV-survivin shRNA, pHelper 1.0 and pHelper 2.0, and the titer of the lentivirus was determined. The recombinant lentivirus was injected into human ectopic endometrial cells and the survivin mRNA expression was examined by semi-quantitative reverse transcription-polymerase chain reaction (RT-PCR) in comparison with that in the non-transfected and blank vector-transfected human ectopic endometrial cells.</p><p><b>RESULTS</b>PCR analysis and DNA sequencing confirmed correct insertion of the shRNA sequence into the lentiviral vector. The titer of virus after packaging was 8x10(8) U/ml. Survivin mRNA expression in human ectopic endometrial cells transfected by LV-survivin shRNA was significantly inhibited compared with those in the non-transfected and empty vector transfected human ectopic endometrial cells (P<0.01), and no significant difference was found between the latter two groups.</p><p><b>CONCLUSION</b>The lentiviral shRNA vector of survivin gene constructed can effectively inhibit the expression of survivin gene in human ectopic endometrial cells in vitro. This vector provides a tool for investigating the role of survivin gene in the occurrence and progression of endometriosis and for searching new therapeutic targets.</p>

To evaluate the neutralizing abilities of anti-dengue virus antibodies with nonstructural protein 1 antigen capture enzyme-linked immunosorbent assay / 中华预防医学杂志

<p><b>OBJECTIVE</b>To produce neutralizing antibodies against envelope protein domain III (EDIII) of dengue virus serotype I (DENV-1) and evaluate the nonstructural protein 1 (NS1) antigen capture enzyme-linked immunosorbent assay (ELISA) for identification of antibody neutralizing abilities.</p><p><b>METHODS</b>Five BALB/c mice and one New Zealand Rabbit were immunized with recombinant EDIII protein of DENV-1 for the production of hybridomas and hyperimmune sera. Indirect ELISA, immunofluorescence assay (IFA) and Western Blot analyses were applied to identify specificity of antibodies. Comparing to plaque reduction neutralization test (PRNT), the new established DENV-1 specific NS1 antigen capture ELISA was used for detecting the neutralizing abilities of these antibody.</p><p><b>RESULTS</b>Four strains of monoclonal antibodies (mAbs) named 1A1, 1B3, 3D3 and 9D6 and one hyperimmune serum of rabbit were obtained, all of which were approved to have neutralizing abilities to DENV-1 with the PRNT titer of 1:1024, 1:512, 1:256, 1:4096 and 1:4096. MAb 3D3 with the lowest neutralization titer in PRNT had not shown neutralizing ability to DENV-1 in NS1 antigen capture ELISA, while MAbs 1A1, 1B3 and 9D6 and the rabbit hyperimmune serum could protect the C6/36 from being infected by DENV-1 with the neutralization titer of 1:32, 1:32, 1:128 and 1:128 in this assay.</p><p><b>CONCLUSION</b>NS1 antigen capture ELISA could be used to identify antibody neutralizing abilities to DENV, it was a faster and more convenient way to screen antibodies with high neutralization titer and might also be used as one of the methods to evaluate the effects of vaccines.</p>

Expression and identification of H5 subtype hemagglutinin of avian influenza A virus in insect cells / 南方医科大学学报

<p><b>OBJECTIVE</b>To clone and express avian influenza A virus [A/Hong Kong/482/97(H5N1)] H5 subtype hemagglutinin in baculovirus-insect cell expression system and investigate the antigenicity and bioactivity of the recombinant protein.</p><p><b>METHODS</b>H5 gene of influenza A virus was amplified by PCR. The recombinant bacmid was obtained by cloning the gene to the donor plasmid of pFastBacHTB and transformed into DH10Bac competent cells. The recombinant baculovirus stock was prepared by transfecting the recombinant bacmid DNA into the insect cell line for protein expression after amplification. Immunofluorescene assay (IFA) and Western blotting were performed to identify the antigenicity of the recombinant protein, and hemagglutination assay was used to identify its bioactivity.</p><p><b>RESULTS</b>The recombinant his-H5 protein was expressed in the insect cells with a relative molecular mass of 64,000, which showed erythrocyte-agglutinating activities with the red blood cells of guinea pig. Western blotting and IFA demonstrated that the recombinant his-H5 could be recognized and bound by standard anti-H5 sera.</p><p><b>CONCLUSION</b>The recombinant his-H5 with a post-translation modification is successfully obtained in insect cells, which may provide a potential source for further study of the antigen's biological function and for production of the subunit vaccine or monoclonal antibodies.</p>

Antigenicity analysis of nucleocapsid proteins of 3 human coronaviruses SARS-CoV, 229E and OC43 with their monoclonal antibodies / 南方医科大学学报

<p><b>OBJECTIVE</b>To prepare and characterize monoclonal antibodies (mAbs) against the recombinant nucleocapsid (N) protein of 3 human coronaviruses SARS-CoV, 229E and OC43 and study the antigenic relationship between the 3 N proteins.</p><p><b>METHODS</b>BALB/c mice were immunized with the recombinant N proteins of SARS-CoV, 229E and OC43 to obtain the mAbs by means of hybridoma. Screening and identification of the mAbs were performed using indirect enzyme-linked immunosorbent assay (ELISA), Western blotting and indirect immunofluorescence assay. Cross-reactivity between the N proteins of the 3 coronaviruses was analyzed with the prepared mAbs.</p><p><b>RESULTS</b>The mAbs against the recombinant N proteins of SARS-CoV, 229E and OC43 were obtained, which reacted specifically with the corresponding viral N protein as shown by indirect ELISA, Western blotting and indirect immunofluorescence assay. No cross-reactivity was found between the 3 N proteins.</p><p><b>CONCLUSION</b>The prepared mAbs against the recombinant N proteins may provide valuable assistance in studying antigenic relationships of N proteins between the 3 human coronaviruses.</p>

Development and application of triple antibodies-based sandwich ELISA for detecting nucleocapsid protein of SARS-associated coronavirus / 中华流行病学杂志

<p><b>OBJECTIVE</b>To prepare and characterize monoclonal antibodies (mAb) and polyclonal antibodies against nucleocapsid (N) protein of severe acute respiratory syndrome (SARS)-associated coronavirus (SARS-CoV) and to establish antibodies-based sandwich ELISA for detecting N protein of SARS-CoV, which might apply to early diagnosis of patients with SARS-CoV infection.</p><p><b>METHODS</b>BALB/c mice were immunized with purified recombinant N protein of SARS-CoV for producing mAbs, and New Zealand white rabbits were immunized for producing polyclonal antibodies. The identification of antibodies was performed using indirect enzyme-linked immunosorbent assay (ELISA), indirect fluorescent-antibody assay (IFA), and Western immunoblotting. Capturing and detecting antibodies were selected by pairing the mAbs and polyclonal antibodies one by one and an antibodies-based sandwich antigen capture ELISA was used for detecting N antigen of SARS-CoV.</p><p><b>RESULTS</b>Nine mAbs and hyperimmune rabbit polyclonal antibodies, specifically against SARS-CoV nucleocapsid protein were obtained. Using paired ELISA assay, three mAbs N1E8, N8E1 and N10E4 were selected as capturing antibody and rabbit polyclonal antibodies as detecting antibody then triple antibodies-based sandwich ELISA was established following horseradish peroxidase (HRP)-conjugated goat anti-rabbit immunoglobulin G. The recombinant N protein was used as a standard to establish a detection sensitivity of approximated 50 pg/ml with this assay. When tested with 420 serum specimens from serologically confirmed SARS patients, the positive rates of serum N protein were 90.1%, 23% and 0%, in which sera collected from 1 to 10 days, 11 to 20 days and beyond 21 days respectively after the onset of symptoms. The specificity of the assay was 99.86% in 715 control serum specimens. There was no cross-reaction with other respiratory viruses and coronaviruses.</p><p><b>CONCLUSION</b>Specific and high affinity mAbs and rabbit polyclonal antibodies were obtained. By paired and optimized sandwich ELISA, a sensitive and specific antigen capture ELISA was established for detecting N antigen of SARS-CoV, which might apply to early diagnosis, source tracing and epidemiological studies of SARS.</p>

Association between gene mutation of cytochrome P450 1A1 in exon 7 A4889G locus and susceptibility to endometriosis / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To assess the possible association between gene mutation of cytochrome P450 1A1(CYP1A1) in exon 7 A4889G locus and the susceptibility to endometriosis (EM).</p><p><b>METHODS</b>Allele specific-polymerase chain reaction method was used to analyze gene mutation in exon 7 A4889G locus of CYP1A1 in 76 patients with endometriosis and 80 healthy controls.</p><p><b>RESULTS</b>The frequency of allele G on A4889G locus of CYP1A1 gene showed a significant difference between the study cohort and the control group (Chi2=7.498, P<0.01), with an odds ratio of 1.957. Statistically significant difference in the frequencies of genotypes AA, AG and GG was observed between the two groups (Chi2=6.915, P<0.05). Individuals with homozygotes for G allele were at higher risk of suffering from EM when compared against those with homozygotes for A allele, the odds ratio being 3.437 (Chi2=5.430, P<0.05).</p><p><b>CONCLUSION</b>The above results suggest that gene mutation of CYP1A1 in exon 7 A4889G locus might be a genetic susceptible factor of endometriosis. The mutation allele of CYP1A1 gene appears to increase the risk of endometriosis.</p>