ABSTRACT
【Objective】 To assess three severe acute respiratorysyndrome coronavirus 2 (SARS-CoV-2) enzyme linked immunosorbent assays (ELISA) and one pseudotype lentivirus-based neutralization test (ppNAT) in detecting the convalescent plasma antibody levles from COVID-19. 【Methods】 30 COVID-19 convalescent plasma samples were screened for antibodies against SARS-CoV-2 using three kinds of SARS-CoV-2 ELISA reagents and one ppNAT test in Shenzhen. The controls consisted of plasma samples from 32 healthy blood donors in February 2019. The diagnostic efficacy analysis of various SARS-CoV-2 ELISA reagents was performed using real-time fluorescent Polymerase Chain Reaction (RT-PCR). We also analyzed correlation between different immunological reagents and the age, gender, hospitalization, and severity of illness. 【Results】 The positive yielding rate of ppNAT and three kinds of IgG ELISA was higher than that of IgM ELISA. The positive yielding rates of three kinds of IgG ELISA were 100%(30/30), 93.33%(28/30), and 96.67%(29/30) respectively, while the yielding rates in control group were all 0. The positive yielding rate of three IgM ELISAs were 93.33%(28/30), 70%(21/30)and 46.67% (14/30). All the cases from negative control group were negative for IgG and IgM. Pearson correlation coefficient was calculated; there was a strong correlation between ELISA reagent 2 IgG and ELISA reagent 3 IgG (r=0.765, P0.05). 【Conclusion】 In the convalescent plasma with nucleic acid confirmed covid-19, the yielding rates of different IgM antibodies varied greatly. Antibody levels were influenced by age to some extent.
ABSTRACT
【Objective】 To analyze the viability of 2 different blood screening strategies against SARS-CoV-2 in low risk populations, so as to provide references for the formulation of blood screening strategy. 【Methods】 Two screening strategies for antibodies against SARS-CoV-2 were adopted: 1) the total antibody were initially screened for all samples, and the antibody IgG and IgM were retested in those primary positive samples; 2) only antibody test of IgG and IgM for all samples. And SARS-CoV-2 nucleic acid was detected in parallel. Reactive samples was confirmed by neutralization test. The sensitivity, specificity and true positive rate of two strategies were calculated. 【Results】 None was positive for SARS-CoV-2 nucleic acid among 880 samples. Four truly positive samples were implicated in 9 (1.02%, 9/880) initially reactive samples in total antibody test; 3 in 26 (2.95%, 26/880) initially IgG or IgM reactive samples. 【Conclusion】 The first strategy is superior to the second strategy in the sensitivity and specificity, and is recommended for the detection of SARS-CoV-2 antibody in low risk populations.
ABSTRACT
Objective To design experimental conditions of Riboflavin combining with ultraviolet light illumination for pathogen inactivation and to verify its effect.Methods The effects of multi-factors,such as Riboflavin concentrates,dosage of ultraviolet irradiation,pH value and medium,were observed on E.coli inactivation by photochemical method when it was used as an indicating germ in phosphorus solution(PBS)and taken count by smearing Mac-lonkey agar plates for colony-forming units.Results The reduction of E.coli reached 3.87 logs when the system was treated with 12.5 umol/L riboflavin and 3.0mJ/ml of ultraviolet light at 254nm in PBS medium.Conclusion E.coli in PBS medium was sensitized to low concentrates of Riboflavin and low dosage of ultraviolet irradiation.
ABSTRACT
Objective To study the morphology changes and the expression of phosphatidyl serine(PS) in apheresis platelets(Plts) during storage,also to analyze their relationship,in order to provide laboratorial evidence for the in vitro storage period of plts.Methods The morphological changes of plts during 8-day storage were detected by May-Grunwald-Giemsa dyeing method,and the expression of PS on platelet membrane was tested by flow cytometry(FCM).Results The morphological lesions appeared on the fourth day of storage,because the modified morphological score(MMS) of 4-day group was significantly lower than that of fresh plts(t=2.341,P