21 Background: At present, PCR-based nucleic acid detection cannot meet the demands 22 for coronavirus infectious disease (COVID-19) diagnosis. Immunosorbent Assay (ELISA) kits based on recombinant SARS-CoV-2 nucleocapsid 27 protein (rN) and spike protein (rS) were used for detecting IgM and IgG antibodies, 28 and their diagnostic feasibility was evaluated.29 Results: Among the 214 patients, 146 (68.2%) and 150 (70.1%) were successfully 30 diagnosed with the rN-based IgM and IgG ELISAs, respectively; 165 (77.1%) and 31 159 (74.3%) were successfully diagnosed with the rS-based IgM and IgG ELISAs, 32 respectively. The positive rates of the rN-based and rS-based ELISAs for antibody 33 (IgM and/or IgG) detection were 80.4% and 82.2%, respectively. The sensitivity of 34 the rS-based ELISA for IgM detection was significantly higher than that of the 35 rN-based ELISA. We observed an increase in the positive rate for IgM and IgG with 36 an increasing number of days post-disease onset (d.p.o.), but the positive rate of IgM 37 dropped after 35 d.p.o. The positive rate of rN-based and rS-based IgM and IgG 38 ELISAs was less than 60% during the early stage of the illness 0-10 d.p.o., and that of 39 IgM and IgG was obviously increased after 10 d.p.o.40 Conclusions: ELISA has a high sensitivity, especially for the detection of serum 41 samples from patients after 10 d.p.o, it can be an important supplementary method for 42 on June 9, 2020 by guest http://jcm.asm.org/ Downloaded from COVID-19 diagnosis.43

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Using rapid prototyping technology, three-dimensional (3D) structures composed of hepatocytes and gelatin hydrogel have been formed. This technique employs a highly accurate 3D micropositioning system with a pressure-controlled syringe to deposit cell/biomaterial structures with a lateral resolution of 10 microm. The pressure-activated micro-syringe is equipped with a fine-bore exit needle for which a wide variety of 3D patterns with different arrays of channels (through-holes) were created. More than 30 layers of a hepatocyte/gelatin mixture were laminated into a high spacial structure using this method. The laminated hepatocytes remained viable and performed biological functions in the construct for more than 2 months. The rapid prototyping technology offers potential for eventual high-throughout production of artificial human tissues or organs.

21 Background: At present, PCR-based nucleic acid detection cannot meet the demands 22 for coronavirus infectious disease (COVID-19) diagnosis. Immunosorbent Assay (ELISA) kits based on recombinant SARS-CoV-2 nucleocapsid 27 protein (rN) and spike protein (rS) were used for detecting IgM and IgG antibodies, 28 and their diagnostic feasibility was evaluated. 29 Results: Among the 214 patients, 146 (68.2%) and 150 (70.1%) were successfully 30 diagnosed with the rN-based IgM and IgG ELISAs, respectively; 165 (77.1%) and 31 159 (74.3%) were successfully diagnosed with the rS-based IgM and IgG ELISAs, 32 respectively. The positive rates of the rN-based and rS-based ELISAs for antibody 33 (IgM and/or IgG) detection were 80.4% and 82.2%, respectively. The sensitivity of 34 the rS-based ELISA for IgM detection was significantly higher than that of the 35 rN-based ELISA. We observed an increase in the positive rate for IgM and IgG with 36 an increasing number of days post-disease onset (d.p.o.), but the positive rate of IgM 37 dropped after 35 d.p.o. The positive rate of rN-based and rS-based IgM and IgG 38 ELISAs was less than 60% during the early stage of the illness 0-10 d.p.o., and that of 39 IgM and IgG was obviously increased after 10 d.p.o.40Conclusions: ELISA has a high sensitivity, especially for the detection of serum

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