Study on the Technical Parameters for Estimating HIV-1 Incidence by Using a Recombinant Antigen-based Capture Enzyme Immunoassay - China.

Introduction: A novel recombinant antigen-based capture enzyme immunoassay (RAg-CEIA) was optimized and used to determine technical parameters for estimating human immunodeficiency virus type 1 (HIV-1) incidence in China.

Methods: We employed orthogonal experimental design to optimize RAg-CEIA by adjusting raw material dilution ratios. The assay was used to measure normalized optical density (ODn) values in 171 longitudinal plasma specimens from 51 HIV-1 seroconverting individuals, plotted against estimated days post-seroconversion.

Development and implementation of a novel method for detecting hepatitis C virus resistance-associated substitutions to NS3, NS5A, and NS5B inhibitors in Linzhou, China.

Background: Hepatitis C virus (HCV) resistance-associated substitutions (RASs) have a significant impact on the treatment of HCV with direct-acting antivirals (DAAs). However, limited research has been conducted, and no standardized methods for detecting RASs in mainland China.

Objectives: To develop and apply a novel method for detecting HCV RASs in HCV RNA-positive patients in Linzhou, China.

Transmission network characteristics based on env and gag sequences from MSM during acute HIV-1 infection in Beijing, China.

Molecular epidemiology can be used to identify human immunodeficiency virus (HIV) transmission clusters, usually using pol sequence for analysis. In the present study, we explored appropriate parameters to construct a simple network using HIV env and gag sequences instead of pol sequences for constructing a phylogenetic tree and a genetic transmission subnetwork, which were used to identify individuals with many potential transmission links and to explore the evolutionary dynamics of the virus among men who have sex with men (MSM) in Beijing. We investigated 70 acute HIV-1 infections, which consisted of HIV-1 subtype B (15.

An alternative strategy to western blot as a confirmatory diagnostic test for HIV infection.

Background: In China, western blot (WB) is the recommended procedure for the diagnosis of HIV infection. However, this technique is time consuming and labor intensive, and its complexity restricts wide application in resource-limited regions.

Objective: The aim of this study was to evaluate the efficacy of a dry blood spots (DBS)-urine paired enzyme-linked immunosorbent assay (ELISA) test, instead of WB, for HIV antibody detection.

Development of a New Limiting-Antigen Avidity Dot Immuno-Gold Filtration Assay for HIV-1 Incidence.

Several laboratory assays on cross-sectional specimens for detecting recent HIV infections were developed, but these assays could not be applied in resource-limited and high HIV-incidence areas. This study describes the development of a rapid assay that can simultaneously detect the presence of HIV-1 antibodies of current and/or recent infection. The dot immuno-gold filtration assay (DIGFA) was used to detect recent infection on the principle of antibody avidity changes between recent and long-term infections.

Next Generation Sequencing-Based Investigation of Potential Patient-to-Patient Hepatitis C Virus Transmission during Hemodialytic Treatment.

We investigated potential patient-to-patient transmission of hepatitis C virus (HCV) in two hemodialysis centers in Beijing, China. Approximately 8.25% (32/388) hemodialysis patients were HCV antibody positive, and 4.

Short Communication: Investigating a Chain of HIV Transmission Events Due to Homosexual Exposure and Blood Transfusion Based on a Next Generation Sequencing Method.

This study investigates a chain of HIV transmission events due to homosexual exposure and blood transfusion in China. The MiSeq platform, a next generation sequencing (NGS) system, was used to obtain genetic details of the HIV-1 env region (336 base pairs). Evolutionary analysis combined with epidemiologic evidence suggests a transmission chain from patient T3 to T2 through homosexual exposure and subsequently to T1 through blood transfusion.

Recalibration of the limiting antigen avidity EIA to determine mean duration of recent infection in divergent HIV-1 subtypes.

Background: Mean duration of recent infection (MDRI) and misclassification of long-term HIV-1 infections, as proportion false recent (PFR), are critical parameters for laboratory-based assays for estimating HIV-1 incidence. Recent review of the data by us and others indicated that MDRI of LAg-Avidity EIA estimated previously required recalibration. We present here results of recalibration efforts using >250 seroconversion panels and multiple statistical methods to ensure accuracy and consensus.

[Contact tracing of a possible case of HIV sexual transmission by using Miseq platform].

Objective: An approach for analysis of HIV quasispecies using Miseq high-throughput sequencing platform (hereinafter referred to as Miseq platform) was established and applied to contact tracing for a possible case of HIV sexual transmission.

Methods: Four plasma specimens were collected from 2 HIV infections (P1 and P2) suspected to be involved in the sexual transmission and 2 local HIV infections as controls (P3 and P4). The RNAs were extracted from the specimens and then reverse-transcribed into cDNA.

[Molecular investigation of a possible case of HIV transmission after a blood transfusion].

Objective: A molecular technique based on quasispecies analysis for tracing postexposure HIV transmission was applied in an investigation of a possible case of HIV transmission after blood transfusion.

Methods: Sixteen plasma specimens were collected from 3 HIV infections (T1-T3) involved in a possible HIV transmission chain and 13 HIV/AIDS (C1-C13) controls. The RNAs were extracted and then amplified by RT-PCR, the PCR products were cloned and sequenced.

Two types of nanoparticle-based bio-barcode amplification assays to detect HIV-1 p24 antigen.

Background: HIV-1 p24 antigen is a major viral component of human immunodeficiency virus type 1 (HIV-1) which can be used to identify persons in the early stage of infection and transmission of HIV-1 from infected mothers to infants. The detection of p24 is usually accomplished by using an enzyme-linked immunosorbent assay (ELISA) with low detection sensitivity. Here we report the use of two bio-barcode amplification (BCA) assays combined with polymerase chain reaction (PCR) and gel electrophoresis to quantify HIV-1 p24 antigen.

Detection of recent HIV-1 infection using a new limiting-antigen avidity assay: potential for HIV-1 incidence estimates and avidity maturation studies.

Background: Accurate and reliable laboratory methods are needed for estimation of HIV-1 incidence to identify the high-risk populations and target and monitor prevention efforts. We previously described a single-well limiting-antigen avidity enzyme immunoassay (LAg-Avidity EIA) to detect recent HIV-1 infection.

Methods: We describe here further optimization and characterization of LAg-Avidity EIA, comparing it to the BED assay and a two-well avidity-index (AI) EIA.

[Comparison of three HIV antibody confirmatory assay kits in confirming early HIV infection].

Objective: This study was to compare the performance of three HIV antibody confirmatory assay kits in confirming early HIV infection.

Methods: Five HIV antibody-positive plasma specimens were ten-fold serially diluted and then detected by ELISA. The above diluted specimens were detected with the following three HIV antibody confirmatory assay kits to analyze their sensitivity, including Wantai-RIBA (Recombinant immunoblot assay, Beijing Wantai Biological Pharmacy, China), MP-WB (HIV Blot 2.

Quality assurance in the HIV/AIDS laboratory network of China.

Background: In 2009, there were 8273 local screening laboratories, 254 confirmatory laboratories, 35 provincial confirmatory central laboratories and 1 National AIDS Reference Laboratory (NARL) in China. These laboratories were located in Center for Disease Control and Prevention (CDC) facilities, hospitals, blood donation clinics, maternal and child health (MCH) hospitals and border health quarantine health-care facilities.

Methods: The NARL and provincial laboratories provide quality assurance through technical, bio-safety and managerial training; periodic proficiency testing; on-site supervisory inspections; and commercial serologic kit evaluations.

Current HIV-2 diagnostic strategy overestimates HIV-2 prevalence in China.

A significant number of HIV-2 infections have been reported in China using Western blot as per current guidelines for HIV-2 diagnosis in China. However, most specimens were also positive on HIV-1 Western blot suggesting cross-reactivity and possible overestimation. We carried out the current study to evaluate a strategy to diagnose the HIV-2 infections in China.

Antibody responses to individual proteins of SARS coronavirus and their neutralization activities.

A novel coronavirus, the severe acute respiratory syndrome (SARS) coronavirus (SARS-CoV), was identified as the causative agent of SARS. The profile of specific antibodies to individual proteins of the virus is critical to the development of vaccine and diagnostic tools. In this study, 13 recombinant proteins associated with four structural proteins (S, E, M and N) and five putative uncharacterized proteins (3a, 3b, 6, 7a and 9b) of the SARS-CoV were prepared and used for screening and monitoring their specific IgG antibodies in SARS patient sera by protein microarray.

Retrospective serological investigation of severe acute respiratory syndrome coronavirus antibodies in recruits from mainland China.

Different assays were used to analyze 1,621 serum specimens collected from military recruits from the People's Republic of China in 2002 for severe acute respiratory syndrome (SARS) coronavirus antibodies. The results demonstrated that the subjects either had rarely been exposed to the virus before the 2003 SARS outbreak or had not been exposed but the nucleocapsid protein cross-reacted with other antibodies in humans.

Use of the COOH portion of the nucleocapsid protein in an antigen-capturing enzyme-linked immunosorbent assay for specific and sensitive detection of severe acute respiratory syndrome coronavirus.

Antibody detection with a recombinant COOH portion of the severe acute respiratory syndrome (SARS) coronavirus nucleocapsid (N) protein, N13 (amino acids 221 to 422), was demonstrated to be more specific and sensitive than that with the full-length N protein, and an N13-based antigen-capturing enzyme-linked immunosorbent assay providing a convenient and specific test for serodiagnosis and epidemiological study of SARS was developed.

Antigenicity analysis of different regions of the severe acute respiratory syndrome coronavirus nucleocapsid protein.

Background: The widespread threat of severe acute respiratory syndrome (SARS) to human health has made urgent the development of fast and accurate analytical methods for its early diagnosis and a safe and efficient antiviral vaccine for preventive use. For this purpose, we investigated the antigenicity of different regions of the SARS coronavirus (SARS-CoV) nucleocapsid (N) protein.

Methods: The cDNA for full-length N protein and its various regions from the SARS-CoV was cloned and expressed in Escherichia coli.

[Development of a rapid separating incubation method for detection of Escherichia coli O157:H7 in food].

To detect Escherichia coli O157:H7 in food, a selective and differential medium, CTV-MUG-RSMAC agar, was designed. Using this medium, the growth of most interfering organisms could be inhibited, and three main biochemical characteristics, including sorbitol-negative, rahmnose-negative and MUG-negative, to identify E. coli O157:H7 could also be simultaneously recognized.