Seropositive Reaction Rates of 9 B-Cell Epitopes of the SARS-CoV-2 Spike Protein and the Relationship between the Epitopes and Neutralizing Antibody.

Objective: The aim of the study was to analyze the relationship between serum antibody and neutralizing antibody titers in convalescent coronavirus disease 2019 (COVID-19) patients with different disease severities, and the seropositive reaction rates of 9 reported B-cell epitopes of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).

Methods: Serum IgG and total antibody titers of 165 convalescent COVID-19 patients were determined by chemiluminescence, the serum neutralization antibody titers were determined by microneutralization assay, and the S/CO values of 9 peptides were detected by indirect enzyme-linked immunosorbent assay. Correlations between the aforementioned indexes were statistically analyzed, and differences in patients with different diseases severities were evaluated.

A newly identified linear epitope on non-RBD region of SARS-CoV-2 spike protein improves the serological detection rate of COVID-19 patients.

Background: Serological test is helpful in confirming and tracking infectious diseases in large population with the advantage of fast and convenience. Using the specific epitope peptides identified from the whole antigen as the detection antigen is sensitive and relatively economical. The development of epitope peptide-based detection kits for COVID-19 patients requires comprehensive information about epitope peptides.

Study on the COVID-19 infection status, prevention and control strategies among people entering Shenzhen.

Background: The novel coronavirus disease 2019 (COVID-19) confirmed cases overseas have continued to rise in the last months, and many people overseas have chosen to return to China. This increases the risk of a large number of imported cases which may cause a relapse of the COVID-19 outbreak. In order to prevent imported infection, the Shenzhen government has implemented a closed-loop management strategy using nucleic acid testing (NAT) for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and requiring 14 days of medical observation for individuals with an overseas tour history (Hong Kong, Macao, Taiwan province and other countries).

Insight into the practical performance of RT-PCR testing for SARS-CoV-2 using serological data: a cohort study.

Background: Virological detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) through RT-PCR has limitations for surveillance. Serological tests can be an important complementary approach. We aimed to assess the practical performance of RT-PCR-based surveillance protocols and determine the extent of undetected SARS-CoV-2 infection in Shenzhen, China.

Incidence of novel coronavirus (2019-nCoV) infection among people under home quarantine in Shenzhen, China.

Background: Since the outbreak of 2019-nCoV in December, Chinese government has implemented various measures including travel bans, centralized treatments, and home quarantines to slowing the transmission across the country. In this study, we aimed to estimate the incidence of 2019-nCoV infection among people under home quarantine in Shenzhen, China.

Methods: We used a stratified multistage random sampling method to recruit participants and collected demographic information and laboratory results of people under home quarantine.

Genomic characterization of influenza A (H7N9) viruses isolated in Shenzhen, Southern China, during the second epidemic wave.

There were three epidemic waves of human infection with avian influenza A (H7N9) virus in 2013-2014. While many analyses of the genomic origin, evolution, and molecular characteristics of the influenza A (H7N9) virus have been performed using sequences from the first epidemic wave, genomic characterization of the virus from the second epidemic wave has been comparatively less reported. In this study, an in-depth analysis was performed with respect to the genomic characteristics of 11 H7N9 virus strains isolated from confirmed cases and four H7N9 virus strains isolated from environmental samples in Shenzhen during the second epidemic wave.

Seroprevalence to avian influenza A(H7N9) virus among poultry workers and the general population in southern China: a longitudinal study.

Background: Confirmed cases of avian influenza A(H7N9) virus infection in humans continue to occur in mainland China. Few confirmed cases have occurred in poultry workers despite potentially higher rates of exposure.

Methods: A serological survey was conducted in May and December 2013 in poultry market workers, and in March and September 2013 in the general population.

Epidemiological dynamics and phylogeography of influenza virus in southern China.

Background: Understanding the epidemiological dynamics of influenza virus is central to surveillance and vaccine strain selection. It has been suggested that tropical and subtropical regions represent the global source of influenza epidemics. However, our understanding of the epidemiological dynamics of influenza virus in these regions is limited by a relative lack of long-term data.

[Analyses of serological and genetic characteristics on novel H1N1 influenza A virus from the infected patient in Shenzhen].

Analysis of serological and genetic characteristics on 2009 swine-origin influenza A (H1N1) virus (S-OIV) isolated from four patients with severe disease in Shenzhen were performed. Microneutralization assay showed that the neutralizing antibody titers of the infected patients did not exceed 1 : 20 in a short term post infection, which could not neutralize the viruses efficiently. Hemagglutination inhibition (HI) tests confirmed that the antigenicity of S-OIV from the patients was distinct from the seasonal influenza A virus, but similar to the reference strains of S-OIV.

[Identification and sequence analysis of E gene of Dengue virus type 2 strain isolated from patient serum in Shenzhen].

Objective: To isolate and identify the pathogen of Dengue fever from Shenzhen city in 2005 - 2006, and to analyze the molecular characteristics of the isolated Dengue virus strain as well as to explore its possible origin.

Methods: IgM and IgG of serum samples taken from 60 suspected Dengue fever patients were detected by ELISA and immunochromatography, and 9 specimens were positive. Nine samples from patients with early stage Dengue fever were used to isolate virus with C6/36 cell line and the positive cell cultures were identified by MGB fluorescent PCR.

[Epidemiological and molecular characterization of seasonal influenza A/H3N2 viruses circulating in Shenzhen, 2005 - 2007].

Objective: To determine the epidemiological characteristics of seasonal influenza in Shenzhen from 2005 to 2007 and the molecular variation of HA1 domain of influenza H3N2 viruses.

Methods: The consultation rate for influenza-like illness (ILI) were calculated weekly for indicating the influenza activities (the Shenzhen Influenza Surveillance System mainly consisted of 16 institutions with 9 hospitals, 6 districts and one municipal centers of disease control and prevention). Pharyngeal swabs from the cases of ILI, which were collected during 2005 to 2007 from the city-wide and quality-controlled surveillance network, were used to propagate the viruses.

[Rapid detection of influenza virus N2 subtype by fluorescence quantitative RT-PCR].

Objective: Developing a rapid method to detect influenza virus N2 subtype by fluorescence real-time quantitative RT-PCR.

Methods: According to conservative sequences of NA gene of influenza virus N2 subtype, a pair primers and Taq-man probe were designed, respectively. Using one step RT-PCR kit to set up real-time RT-PCR system for detection of influenza virus N2 subtype, after the standard quantitative curve of the assay was established using 10-fold serial dilution of TCID50, the sensitivity was determined.

[Study on molecular epidemiological characteristics of influenza H1N1 viruses circulating in Shenzhen, China from 2005 to 2007].

Objective: To study the genetic and epidemiological characteristics of HA1 of influenza H1N1 viruses circulating in Shenzhen from 2005 to 2007.

Methods: The HA1 region was analyzed by RT-PCR and subsequently sequenced to analyze the HA1 genetic evolution. Phylogenetic analysis was confirmed on the homology of nucleotide comparing with the reference viruses of vaccines recommended by WHO and representative virus confirmed by China CDC.

[Study on the molecular characteristic of natural infection of rodents with Hantaviruses in Shenzhen city].

Objective: In order to investigate Hantavirus (HV) infection of captured rodents and to understand the genotypes and the molecular characteristic of Hantaviruses in Shenzhen.

Methods: The captured rodents were classified and the density of distribution was calculated. A total of 472 animals were captured, among which Rattus norvegicus was the dominant group.

[Study on characterization of the hemagglutinin gene of avian influenza virus H5N1 subtype originated from the pan Pacific regions].

Objective: To understand the gene characterization of hamagglutinin (HA) of AIV H5N1 subtype originated from the pan Pacific regions in order to find out its mutation possibility.

Methods: 50 HA gene sequences originated from pan Pacific regions were downloaded, including Thailand, Vietnam, Hong Kong, Indonesia, mainland of China, Mongolia and Russia, the alignments of nucleic acid and amino acid sequence of HA gene were analyzed, and the phylogenetic relationships among 50 H5N1 high pathogenic avian influenza (HPAI) virus were evaluated by bio-software DNASTAR 5.0 and MEGA 3.

[A case of human highly pathogenic avian influenza in Shenzhen, China: application of field epidemiological study].

Objective: Based on analyzing the characteristics of a case with human avian influenza and the effects of field epidemiological study.

Methods: An emergency-response-system was started up to follow the probable human Highly Pathogenic Avian Influenza case initially detected by the "Undefined Pneumonia Surveillance System of Shenzhen". Public health professionals administered several epidemiologic investigations and giving all the contacts of the patient with a 7-day-long medical observation for temporally related influenza-like illness.

Serologic and genetic characterization analyses of a highly pathogenic influenza virus (H5N1) isolated from an infected man in Shenzhen.

Highly pathogenic avian influenza (HPAI) H5N1 virus caused a wave of outbreaks in China during 2005--2006, resulting in a total of 20 cases of human infection in 14 provinces of China. On June16, 2006, a case of H5N1 human infection was confirmed in Shenzhen. The virus isolated from the patient, A/Guangdong/2/06, was characterized genetically and the relationship between the tracheal virus load and the antibody titer of the infected man was analyzed.

[Laboratory diagnosis and molecular characterization analysis of the H5N1 influenza virus isolated from the first human case in Shenzhen, China].

The tracheal aspirates and serum samples of a suspected human case of high-pathogenic avian influenza (firstly found in Shenzhen, China) were collected and tested by a series of assays. The results showed that the RNA extracted from the tracheal aspirate specimens of the patient was confirmed positive for H5N1 avian influenza virus by Real-time PCR. The H5N1 avian influenza virus was isolated from patient's tracheal aspirates on MDCK cell and was named A/Guangdong/2/06(H5N1).

A multiplex real-time RT-PCR for detection and identification of influenza virus types A and B and subtypes H5 and N1.

A multiplex real-time RT-PCR method for the simultaneous detection of influenza virus types A and B and identification of subtypes H5 and N1 in a single tube is described. The method was developed with four sets of primers and probes which were specific to influenza virus (sub)types A, B, H5, and N1, and evaluated by using a total of 40 influenza virus reference strains, including 17 avian influenza A (12 H5N1, 1 H1N1, 1 H3N2, 1 H4N6, 1 H7N3, and 1 H9N2), 18 human influenza A (11 H3N2, 6 H1N1 and 1 H5N1) and 5 influenza B viruses. The method exhibited a high specificity and sensitivity of approximately 10(1)-10(2)copies/microl for each (sub)type and a high reproducibility with intra- and inter-assay CV from 0.

[Surveillance on natural infection of rodents with hantavirus in Shenzhen city and identification of a hantavirus strain SZ2083].

Objective: For clarifying the situation of the natural infection of rodents having hemorrhagic fever with renal syndrome (HFRS) virus and to type Hantavirus (HV) using molecular technique in Shenzhen city in 2005, and offering guidance for prevention and control of HFRS.

Methods: Data on the host animals was collected from the city of Shenzhen. ELISA and indirect immunofluorscent antibody(IFA) test were applied to the specific antibodies against HV in the sera of captured rats.

[Study on the rapid detection of Dengue viruses by Taqman MGB real-time fluorescent PCR].

Objective: To develop the Taqman MGB real-time fluorescent PCR assay for rapid detection of Dengue viruses.

Methods: Using Taqman MGB technique, a pair of universal primers and Taqman MGB probe were designed according to a highly reserved sequence of the 3'-noncoding region of dengue viruses type 1-4. Dengue virus strains were used as standard and Japanese encephalitis virus strains were used as control, the real-time PCR assay for specific and sensitive detection of the dengue viruses was established.

[Rapid detection of influenza virus A by fluorescence quantitative RT-PCR].

Objective: To develop a method to rapidly detect influenza virus type A by fluorescence real-time quantitative RT-PCR.

Methods: According to conservative sequence of influenza virus type A M2 gene, a pair primers and Taqman probe were designed, respectively. After the quantitative curve of the assay were established using tenfold serial dilution of TCID50, the sensitivity and the specificity of clinic samples were determined.

[Evaluation on construction and expression in vitro of nucleic acid vaccine of nucleoprotein of influenza virus A].

Objective: Constructing nucleic acid vaccine of influenza virus A to study the protective effects.

Methods: NP gene was reverse transcripted from influenza virus A and linked with pSECTAG 2/Hygro A to constructed nucleic acid vaccine of influenza virus A. The constructed nucleic acid vaccine was transinfected into VERO cell resorting to lipofectamineTM2000.

[Modified molecular beacon-based dual real-time PCR for detection of SARS virus and its application].

Objective: To develop the modified molecular beacon-based dual fluorescent PCR assays for detection of SARS virus. The assay was applied to the early clinic diagnosis & animal tracking.

Methods: On the basis of the obtained core sequence of open reading frame 1b of the coronavirus polymerase gene sequences, which was published in GenBank, using modified molecular beacon probe, artifical virus techinique and two different fragments amplification with different fluoresce, one set of primers and probe were designed.