key: cord-0752132-ubq4o4pq
authors: Xiao, Ai Tang; Gao, Chun; Zhang, Sheng
title: Profile of specific antibodies to SARS-CoV-2: The first report
date: 2020-03-21
journal: J Infect
DOI: 10.1016/j.jinf.2020.03.012
sha: e69e83feb23c448fd846dcb17a577ea3024442ab
doc_id: 752132
cord_uid: ubq4o4pq

• Profile of specific antibodies to virus in blood can assist diagnosis and reflect disease course. • The preliminary study explored the dynamic profile of IgM and IgG. • Serum IgM to SARS-COV-2 last more than a month indicating the prolonged virus replication in infected patients.

A novel coronavirus (COVID-19) epidemic threatens the world. 1 , 2 Before this study, some studies reported cases of viral detection by RT-PCR at different timepoints throughout the disease course. 3 , 4 However, these reports monitored SARS-CoV-2 in the acute phase of infection. Currently no study reported the profile of specific antibodies to SARS-CoV-2 infection. Profile of specific antibodies in patients' blood can assist diagnosis and reflect the disease course. Here, we first studied the profile of IgM and IgG for SARS-CoV-2 from 34 COVID-19 patients.

A total of 34 hospitalized patients (admission date from Feb 1 st to Feb 29 th , 2020) with confirmed SARS-CoV-2 infection were included in this study. All enrolled patients were confirmed diagnosed of COVID-19 according to the diagnosis and treatment guideline for SARS-CoV-2 from Chinese National Health Committee (Version 5) and the interim guidance from Centers for Disease Control and Prevention. 5 , 6 Blood samples were obtained at different date after onset of symptoms to detect the specific antibodies to SARS-CoV-2. IgM and IgG were analyzed by chemiluminescent immunoassay according to the manufacturer's protocol (Shenzhen Yahuilong Biotechnology Co., Ltd). All data (test dates and results of IgM and IgG) were collected up to the final follow-up date (March 3rd, 2020).

Details of demographic characteristics and test dates and results of IgM and IgG were list in Table 1 . Except for two patients (2 days and 3 days after symptoms onset), all included patients had IgM and IgG tests after 2 weeks from symptoms onset. We categorized patients by weeks according to the date of antibodies test after symptoms onset. In week 3 after symptoms onset, all patients were tested positive for IgM and IgG, with the mean value of 322.80AU/ml and 112.40AU/ml (Reference: < 10AU/ml) respectively. In week 4, all the results were still positive for IgM and IgG. IgM declined while IgG continued to go up, with the mean value of 147.92AU/ml and 157.01AU/ml respectively. In week 5, however, all patients were positive for IgG, while 2 patients (16.7%) got negative results for IgM. IgM level kept going down to 78.03AU/ml and IgG continued up to 163.56AU/ml. At the end of observation (7 weeks), 2 patients (33.3%) got negative results for IgM, while all patients positive for IgG, with the mean value of 21.83AU/ml and 167.16AU/ml respectively. ( Fig. 1 ) Genomic studies have shown that SARS-CoV-2 shared around 80% identity sequencing with SARS-CoV, which caused a global epidemic with 8096 confirmed cases worldwide in 20 02-20 03. 7 Study of case series suggested the viral nucleic acid shedding pattern of patients infected with SARS-CoV-2 is different from SARS-CoV. 3 For SARS-CoV, studies revealed that IgM reached the highest point within 4 weeks and was not detectable on 3 months after onset of symptoms. IgG were persistently detectable up to 24 months. 8 Our results suggested that the profile of specific antibodies to SARS-CoV-2 is similar to SARS-CoV. Detectable and continuous high level of IgM indicated the acute phase of infection. Furthermore, IgM last more than a month indicating the prolonged virus replication in SARS-CoV-2 infected patients. IgG responded later than IgM and persisted high in our study, indicating the humoral immune reaction to protect the body against SARS-CoV-2 virus.

The detection and profile of specific antibodies to SARS-CoV-2 will provide valuable information for rapid screening of suspects, assist diagnosis and evaluate the disease course. Furthermore, concentrated IgG antibody may be informative in vaccine development and treatment for SARS-CoV-2.

All authors declare that there are no conflicts of interest.

No funding resources to declare for this study.

Oral consent was obtained from patients involved before enrollment when data were collected retrospectively.

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