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Cell Rep Med ; 2(6): 100311, 2021 Jun 15.
Article in English | MEDLINE | ID: covidwho-1230816


The ongoing coronavirus disease 2019 (COVID-19) pandemic is a major global public health concern. Although rapid point-of-care testing for detecting viral antigen is important for management of the outbreak, the current antigen tests are less sensitive than nucleic acid testing. In our current study, we produce monoclonal antibodies (mAbs) that exclusively react with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and exhibit no cross-reactivity with other human coronaviruses, including SARS-CoV. Molecular modeling suggests that the mAbs bind to epitopes present on the exterior surface of the nucleocapsid, making them suitable for detecting SARS-CoV-2 in clinical samples. We further select the optimal pair of anti-SARS-CoV-2 nucleocapsid protein (NP) mAbs using ELISA and then use this mAb pair to develop immunochromatographic assay augmented with silver amplification technology. Our mAbs recognize the variants of concern (501Y.V1-V3) that are currently in circulation. Because of their high performance, the mAbs of this study can serve as good candidates for developing antigen detection kits for COVID-19.

J Infect Chemother ; 27(2): 387-389, 2021 Feb.
Article in English | MEDLINE | ID: covidwho-957212


The duration of viral shedding of SARS-CoV-2 is usually less than 10 days. We experienced a COVID-19 case with prolonged viral shedding for 2 months. His cell mediated immunity has been depressed (CD4+T cell <100/µl) due to advanced malignant lymphoma and chemotherapy which had been completed 4 months prior to the onset of symptoms of COVID-19. We administered several treatments against COVID-19, however the results of Polymerase Chain Reaction (PCR) from nasopharyngeal specimens remained positive to SARS-CoV-2 for 2 months. Moreover, virus isolation assays performed on Day 59 also remained positive. He was finally discharged on Day 69 with two consecutive negative PCR results for SARS-CoV-2. Immunocompromised status may prolong viral shedding and it is therefore important for the clinician to take into account this when assessing such patients.

COVID-19/immunology , Immunocompromised Host , Lymphoma/complications , SARS-CoV-2/isolation & purification , Virus Shedding , Antiviral Agents/therapeutic use , COVID-19/complications , COVID-19/therapy , COVID-19/virology , Humans , Lymphoma/virology , Male , Middle Aged , Nasopharynx/virology , RNA, Viral/analysis , Reverse Transcriptase Polymerase Chain Reaction/methods , Time Factors , Treatment Outcome
Kansenshogaku Zasshi ; 94(4):500-506, 2020.
Article in Japanese | WHO COVID | ID: covidwho-694686


The number of the patients with coronavirus disease 2019 (COVID-19) is increasing, and shortage of hospital beds for these patients is a cause for serious concern. Here, we report the clinical course of 11 patients who were admitted to our hospital with COVID-19 that developed during their quarantine period in a large cruise ship, and discuss the factors associated with the disease severity and length of hospitalization. The median age of the 11 patients was 62 years, and 36% were men. The disease severity was mild in 7 patients, moderate in 4 patients, and severe in none of the patients. The median time from symptom onset to disease remission was 13 days for patients with moderately severe disease, and 7 days for patients with mild disease. The median interval from symptom onset to confirmation of the first negative result of PCR was 16 days for patients with moderately severe disease, and 14 days for patients with mild disease. The median time from symptom onset to discharge was 22.5 days for patients with moderately severe disease cases, and 16 days for patients with mild disease. Some patients needed prolonged hospitalization because of persistently positive results of PCR even after remission of symptoms. Comparison between the patient groups with moderately severe disease and mild disease showed that the patients with moderately severe disease were older and had higher serum ferritin and serum amyloid protein (SAA) levels than the patients with mild disease. Even in patients with mild to moderate COVID-19, two to three weeks were required from symptom onset to confirmation of the first negative result of PCR, and this was one of the major factors for prolonged hospitalization. The serum ferritin levels and SAA levels might be predictors of the disease severity.