ABSTRACT
Several commercial assays for SARS-CoV-2 RT-PCR are available but few of them were assessed. We evaluate the Allplex 2019-nCoV (Seegene) assay using 41 nasopharyngeal samples. The rates of agreement were 92.7% and 100% with the GeneFinder COVID-19 plus (Elitech) and the diagnosis of the infectious disease specialist respectively. Four samples display a Ct < 22.0 for the E and RdRp genes while the N gene was not detected, suggesting a variability of the viral sequence. There was no cross-reactivity with other respiratory viruses. The Allplex 2019-nCoV appears as a reliable method, but additional evaluations using more samples are needed. RT-PCR assays should probably include at least 2 viral targets.
Subject(s)
Betacoronavirus/genetics , Coronavirus Infections/diagnosis , Nucleocapsid Proteins/genetics , Pneumonia, Viral/diagnosis , RNA-Dependent RNA Polymerase/genetics , Reverse Transcriptase Polymerase Chain Reaction/methods , Viral Envelope Proteins/genetics , Viral Nonstructural Proteins/genetics , COVID-19 , COVID-19 Testing , Clinical Laboratory Techniques/methods , Coronavirus Envelope Proteins , Coronavirus Nucleocapsid Proteins , Coronavirus RNA-Dependent RNA Polymerase , France , Humans , Nasopharynx/virology , Pandemics , Phosphoproteins , Prospective Studies , SARS-CoV-2ABSTRACT
BACKGROUND: A new enzyme immunoassay based on the simultaneous detection of nucleocapsid proteins of hepatitis C virus (HCV) and anti-HCV (Monolisa HCV antigen-antibody Ultra, Bio-Rad) was evaluated as an alternative to nucleic acid testing (NAT) for the diagnosis of HCV infection during the window period in blood donations. STUDY DESIGN AND METHODS: The study included 107 sequential samples from 10 HCV seroconversion commercial panels; 81 samples were in the preseroconversion phase, and 26 were collected after seroconversion. All samples were tested with HCV antigen-antibody assay and the two minipool (MP) NAT procedures that are routinely used in France (transcription-mediated amplification in pools of 8 and COBAS AmpliScreen HCV test [Roche Diagnostic] in pools of 24 donations). RESULTS: From the 44 samples collected during window period that were MP-NAT-positive, 31 (70.5%) were also positive with the Monolisa HCV antigen-antibody assay. The mean delay in detecting HCV infection between these two methods was 5.1 days (range, 0-24 days). The Monolisa HCV antigen-antibody assay led to a reduction in the window period of 26.8 days (range, 0-72 days). All samples collected after seroconversion were detected with the HCV antigen-antibody assay. The specificity analyzed in 2503 consecutive blood donations was estimated at 99.88 percent. CONCLUSION: This new developed assay presents an improvement for the detection of HCV infection, especially in the early phase of infection when antibodies are undetectable. Although less sensitive than NAT, this assay could be a suitable solution for blood screening in developing countries where NAT (or HCV core antigen-specific assay) is not affordable or its implementation is not feasible.
Subject(s)
Hepacivirus/isolation & purification , Hepatitis C Antibodies/isolation & purification , Hepatitis C/prevention & control , Immunoassay/methods , Viral Core Proteins/isolation & purification , Biomarkers , Blood Banking/methods , Hepacivirus/genetics , Hepacivirus/immunology , Hepatitis C/blood , Hepatitis C/diagnosis , Hepatitis C Antibodies/blood , Hepatitis C Antibodies/immunology , Humans , RNA, Viral/blood , Sensitivity and Specificity , Viral Core Proteins/blood , Viral Core Proteins/immunologyABSTRACT
BACKGROUND: Weak D type carriers cannot be immunized against D except when antigen density is below 400 antigens per RBC, whereas partial D carriers can produce anti-D. STUDY DESIGN AND METHODS: A total of 168 blood samples from Caucasian individuals were studied because of weak D expression and/or anti-D production. Serologic analysis and molecular analysis were performed. RESULTS: In total, 70 partial D and 62 weak D were identified. Among weak D samples, 30 weak D Type 1 and 21 weak D Type 2 alleles were found. Five new alleles were characterized carrying 399G > T, 680T > C, 833G > A, 851C > T, and 1015G > A, respectively. According to previous studies, antigen density was up to 500 for weak D Type 1 and 2, except when there was a dCe haplotype in trans. Antigen density was below 400 antigens per red blood cell for the new variants and most other weak D variants. CONCLUSION: These results provide molecular characterization of five new D variants. They also suggest that it would be advantageous to develop in routine laboratories weak D Type 1 and 2 genotyping for serologically depressed D antigen. It will help to avoid wasting of D- red blood cell units because carriers may safely receive D+ units.