PMC8710376_01
Chest CT findings. CT findings from day 4 of illness showed ground-glass opacities in the right upper lobe and atelectases/infiltrations in both dorsal lower lung fields.
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Chest computed tomography (CT) findings were significant for ground-glass opacities in the right upper lobe and atelectases/infiltrations in both dorsal lower lung fields (Fig. 1), indicative of a COVID-19 type H phenotype.
Detailed serological description of the patient. (A) The anti-nucleocapsid IgG response of the patient measured by the Abbott Architect immunoassay resembled that of other immunocompetent COVID-19 subjects (left). The anti-spike IgG titer of the patient was below the detection limit of the Mokobio immunoassay (middle). The neutralizing activity of the patient's serum against in vitro SARS-CoV-2 infection was negligible, correlating with the attenuated anti-spike IgG response. Neutralizability results were plotted against three seroconverted immunocompetent COVID-19 subjects (COVID-19 #1-3) and a SARS-CoV-2 negative control (negative control) (right). The patient's serum was obtained 25 days after the symptom onset. Dashed lines indicate the cut-off values for assays. (B) A time-course analysis of the patient's serum showed anti-nucleocapsid antibody responses comparable to those of other immunocompetent severe COVID-19 subjects (COVID-19 #1-3), both in magnitude and kinetics, while the anti-spike IgG titer remained below the detection limit of the EUROIMMUN Anti-SARS-CoV-2 ELISA assay. (C) The level of RNAemia, determined by the cycle threshold for N and ORF1ab gene amplification, remained persistently high in the patient, while that of the other immunocompetent COVID-19 subjects (COVID-19 #1-3) gradually declined as their illness subsided. The ORF1ab gene amplicon was never amplified in subject COVID-19 #2.
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Architect SARS-CoV-2 IgG (Abbott Laboratories, Chicago, United States) targeting the nucleocapsid antigen showed an elevated titer, while a SARS-CoV-2 IgG Quantum Dot Immunoassay (Mokobio Biotechnology R&D center, Rockville, United States) targeting the spike-antigen detected no significant signal (Fig. 2A). Accordingly, as antibodies targeting the spike antigen receptor-binding domain are used to determine viral neutralizability, the in vitro viral neutralization assay confirmed that the patient's serum showed negligible viral neutralizability (Fig. 2A). A time-course serial sample analysis revealed that the patient had developed an anti-nucleocapsid antibody response comparable to that of other immunocompetent severe COVID-19 subjects, both in magnitude and kinetics (Fig. 2B). In contrast, the serum anti-spike antibody titer remained below the detection level throughout his clinical course (Fig. 2B). Thus, the viral clearance was significantly delayed, and the level of RNAemia in the patient remained persistently high, while that of the other immunocompetent COVID-19 subjects gradually declined as their illness subsided (Fig. 2C).
Clinical course of the patient. mPSL: methylprednisolone
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The patient's clinical course is summarized in Figure 3.