Antibody Responses to SARS-CoV-2 in Patients With Novel Coronavirus Disease 2019

Abstract

Combining RNA and antibody detections significantly improved the sensitivity of pathogenic diagnosis for COVID-19 in the early phase of infection. A higher titer of Ab was independently associated with a worse clinical classification. Abstract BackgroundThe novel coronavirus SARS-CoV-2 is a newly emerging virus. The antibody response in infected patient remains largely unknown, and the clinical values of antibody testing have not been fully demonstrated. MethodsA total of 173 patients with SARS-CoV-2 infection were enrolled. Their serial plasma samples (n=535) collected during the hospitalization were tested for total antibodies (Ab), IgM and IgG against SARS-CoV-2. The dynamics of antibodies with the disease progress was analyzed. ResultsAmong 173 patients, the seroconversion rate for Ab, IgM and IgG was 93.1%, 82.7% and 64.7%, respectively. The reason for the negative antibody findings in 12 patients might due to the lack of blood samples at the later stage of illness. The median seroconversion time for Ab, IgM and then IgG were day-11, day-12 and day-14, separately. The presence of antibodies was <40% among patients within 1-week since onset, and rapidly increased to 100.0% (Ab), 94.3% (IgM) and 79.8% (IgG) since day-15 after onset. In contrast, RNA detectability decreased from 66.7% (58/87) in samples collected before day-7 to 45.5% (25/55) during day 15-39. Combining RNA and antibody detections significantly improved the sensitivity of pathogenic diagnosis for COVID-19 (p<0.001), even in early phase of 1-week since onset (p=0.007). Moreover, a higher titer of Ab was independently associated with a worse clinical classification (p=0.006). ConclusionsThe antibody detection offers vital clinical information during the course of SARS-CoV-2 infection. The findings provide strong empirical support for the routine application of serological testing in the diagnosis and management of COVID-19 patients.

Evaluation of nine commercial SARS-CoV-2 immunoassays

“…The differences observed for the sensitivity and specificity of the SARS-CoV-2-specific total antibody testing and antibody type ELISAs correspond to previous reports. The Wantai Total Ab ELISA performed as reported by the manufacturer (94.5% sensitivity and 100% specificity) and a separate study (93.1% sensitivity) where the Total Ab ELISA, IgM ELISA and IgG ELISA produced by Beijing Wantai Biological Pharmacy Enterprise were compared [7]. In the latter study, the IgM and IgG ELISAs had lower sensitivities (83% and 65%, respectively) compared to the Total Ab ELISA (93.1%) [7].…”

“…The Wantai Total Ab ELISA performed as reported by the manufacturer (94.5% sensitivity and 100% specificity) and a separate study (93.1% sensitivity) where the Total Ab ELISA, IgM ELISA and IgG ELISA produced by Beijing Wantai Biological Pharmacy Enterprise were compared [7]. In the latter study, the IgM and IgG ELISAs had lower sensitivities (83% and 65%, respectively) compared to the Total Ab ELISA (93.1%) [7]. This notably lower sensitivity for SARS-CoV-2-specific IgG detection is in agreement to that observed here for the Euroimmun IgG ELISA (65%).…”

“…Antibody testing, either using enzyme-linked immunosorbent assay (ELISA) or point-of-care (POC) lateral flow immunoassays, may overcome some of these challenges. SARS-CoV-2-specific antibodies can be detected in in serum of approximately 40% of COVID-19 patients as early as seven days after the onset of symptoms, with seroconversion rates rapidly increasing to >90% by day 14 [7]. In recent studies, antibody testing has been shown to be more sensitive than viral nucleic acid detection after approximately eight days of COVID-19 illness duration [7,8].…”

“…SARS-CoV-2-specific antibodies can be detected in in serum of approximately 40% of COVID-19 patients as early as seven days after the onset of symptoms, with seroconversion rates rapidly increasing to >90% by day 14 [7]. In recent studies, antibody testing has been shown to be more sensitive than viral nucleic acid detection after approximately eight days of COVID-19 illness duration [7,8]. While the combination of PCR and antibody tests is optimal for accurate diagnosis [6], antibody detection will be particularly relevant for the later stages of infection where the virus has been eliminated [5].…”

Comparative computational analysis of SARS-CoV-2 nucleocapsid protein epitopes in taxonomically related coronaviruses

“…In this view, exposure to epitopes from synanthropic animals might confer partial protection from SARS-CoV-2 infection. This would explain, at least in part, the early detection of class G immunoglobulins in newly infected subjects and the big divergence occurring in the clinical manifestation of the SARS-CoV-2 infections, other than preventing epitopes-exposed subjects from the severe form of COVID-19 [16]. Nucleocapsid protein is a highly conserved protein involved in the active phase of the viral infection.…”