Molecular and serological characterization of SARS-CoV-2 infection among COVID-19 patients

Abstract

Background SARS-CoV-2 is a novel coronavirus and the cause of COVID-19. More than 80% of COVID-19 patients exhibit mild or moderate symptoms. In this study, we investigated the dynamics of viral load and antibodies against SARS-CoV-2 in a longitudinal cohort of COVID-19 patients with severe and mild/moderate diseases. Methods Demographic and clinical information were obtained. Serial samples of blood, nasal and pharyngeal and anal swabs were collected at different time points post-onset. SARS-CoV-2 RNA and anti-SARS-CoV-2 antibodies were measured by qRT-PCR and immunoassays, respectively. Results Respiratory SARS-CoV-2 RNA was detectable in 58.0% (58/100) COVID-19 patients upon admission and lasted for a median of 13 days post-onset. In addition, 5.9% (1/17) and 20.2% (19/94) of the blood and anal swab specimens were positive for SARS-CoV-2 RNA, respectively. Anal viral RNA was more frequently detected in the patients who were positive for viral RNA in the respiratory samples upon admission. Specific anti-SARS-CoV-2 antibody developed within two weeks after onset, reached peak approximately 17 days post-onset and then maintained at relatively high level up to 50 days we analyzed in most patients. However, the levels of antibodies were variable among the patients. High titers of antibodies appeared to be associated with the severity of the disease. Furthermore, viral proteins from different sources showed significant difference of serological sensitivity especially during the first week post-onset. Conclusions Our results indicate rapid clearance or self-elimination of viral RNA in about half of the COVID-19 patients upon admission. Viral RNA shedding of SARS-CoV-2 occurred in multiple tissues including the respiratory system, blood, and intestine. Variable levels of specific anti-SARS-CoV-2 antibody may be associated with disease severity. These findings have shed light on viral kinetics and antibody response in COVID-19 patients and provide scientific evidence for infection control and patient management.

ECMO in COVID-19—prolonged therapy needed? A retrospective analysis of outcome and prognostic factors

“…The influence of seroconversion and antibody levels on the course of the disease remains poorly understood and controversial. 43,[47][48][49] In our study population, all patients developed antibodies against SARS-CoV-2. IgG levels after ECMO initiation did not differ between the three groups and therefore, might not have influenced the clinical course.…”

A longitudinal study of SARS-CoV-2-infected patients reveals a high correlation between neutralizing antibodies and COVID-19 severity

“…Recent reports have evaluated the neutralizing activity of sera from COVID-19 patients and the results have been controversial. One study suggested that patients rapidly develop nAbs, 21 whereas other studies have indicated that the humoral response 22 and nAb activity 22 – 24 correlate with several parameters, including the severity of the disease, resulting in the absence of nAb activity detection in a significant number of mild symptomatic and ASYs. 25 However, such assumptions were based on a very limited number of observations, as those studies included less than 10 patients with the most severe forms.…”

The Main Molecular and Serological Methods for Diagnosing COVID-19: An Overview Based on the Literature

“…More precisely, different studies suggest that 14 days after the onset of symptoms is a time period at which serological tests have high sensitivity that is able to replace nucleic acid amplification tests for the effective diagnosis of COVID-19 [ 224 , 225 , 226 ]. In addition, it is important to highlight that it has been demonstrated that more severe cases of COVID-19 have a late humoral response compared to mild/moderate infections [ 227 ], as well as high antibody titers have been shown to be associated with the severity of the disease [ 228 ]. Similar behavior was also found when neutralizing antibody titers were analyzed, where it was reported that asymptomatic patients do not produce a prolonged response [ 229 ], while patients with moderate to moderate symptoms produced robust responses against the SARS-CoV-2 spike protein [ 230 ].…”

“…Similar behavior was also found when neutralizing antibody titers were analyzed, where it was reported that asymptomatic patients do not produce a prolonged response [ 229 ], while patients with moderate to moderate symptoms produced robust responses against the SARS-CoV-2 spike protein [ 230 ]. Li et al [ 228 ] observed the production of antibodies in adults reached their peak at 17 days after the onset of symptoms and then remained at a relatively high level for up to 50 days. Similar behavior was also reported by Roarty et al [ 231 ], who demonstrated that antibody titers in children previously exposed to SARS-CoV-2 remained detectable up to 62 days after the onset of symptoms.…”