key: cord-1056409-y55nuuhb
authors: Sun, Jiufeng; Tang, Xi; Bai, Ru; Liang, Chumin; Zeng, Lilian; Lin, Huifang; Yuan, Runyu; Zhou, Pingping; Huang, Xuhe; Xiong, Qianlin; Peng, Jinju; Cui, Fengfu; Ke, Bixia; Su, Juan; Liu, Zhe; Lu, Jing; Tian, Junzhang; Sun, Ruilin; Ke, Changwen
title: The kinetics of viral load and antibodiesto SARS-CoV-2
date: 2020-09-06
journal: Clin Microbiol Infect
DOI: 10.1016/j.cmi.2020.08.043
sha: 9ac3dcd800e33215c635810a9ae2dd24aab3e577
doc_id: 1056409
cord_uid: y55nuuhb

OBJECTIVES: To understand persistence of the virus in body fluids and immune response of infected host to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), an agent of coronavirus disease 2019 (COVID-19). METHODS: We determined the kinetics of viral load in several body fluids through real time reverse transcription polymerase chain reaction (rRT-PCR), serum antibodies of IgA, IgG and IgM by enzyme linked immunosorbent assay (ELISA), and neutralizing antibodies by microneutralization assay in 35 COVID-19 cases from two hospitals in Guangdong, China. RESULTS: We found higher viral loads and prolonged shedding of virus RNA in severe cases of COVID-19 in nasopharyngeal (1.3×10(6) vs 6.4×10(4), p<0.05; 7∼8w) and throat (6.9×10(6) vs 2.9×10(5), p<0.05; 4∼5w), while comparable in sputum samples (5.5×10(6) vs 0.9×10(6), p<0.05; 4∼5w). Viraemia was rarely detected (2.8%, n=1/35). We detected early seroconversion of IgA and IgG at 1(st) week after illness onset (day 5, 5.7%, n=2/35). Neutralizing antibodies were produced in the second week, and observed in all 35 included cases after 3(rd) week illness onset. The levels of neutralizing antibodies correlated with IgG (r(s)=0.85, p<0.05; kappa=0.85) and IgA (r(s)=0.64, p<0.05; kappa=0.61) in severe, but not mild cases (IgG, r(s)=0.42, kappa=0.33; IgA, r(s)=0.32, kappa=0.22). No correlation with IgM in either severe (r(s)=0.17, kappa=0.06) or mild cases (r(s)=0.27, kappa=0.15) was found. CONCLUSIONS: We revealed a prolonged shedding of virus RNA in upper respiratory tract, and evaluated the consistency production of IgG, IgA, IgM and neutralizing antibodies in COVID-19 cases.

Objectives 24 To understand persistence of the virus in body fluids and immune response of infected 25 host to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), an agent of 

We found higher viral loads and prolonged shedding of virus RNA in severe cases of 35 COVID-19 in nasopharyngeal ( 1.3×10 6 vs 6.4×10 4 , p<0.05; 7~8w) and throat (6.9× 36 10 6 vs 2.9×10 5 , p<0.05; 4~5w), while comparable in sputum samples (5.5×10 6 vs 0.9 37 ×10 6 , p<0.05; 4~5w). Viraemia was rarely detected (2.8%, n=1/35). We detected early 38 seroconversion of IgA and IgG at 1 st week after illness onset (day 5, 5.7%, n=2/35).

Neutralizing antibodies were produced in the second week, and observed in all 35 40 included cases after 3 rd week illness onset. Those were all the patients hospitalized in these two hospitals during that time. All the 80 cases were laboratory confirmed COVID-19 cases. One mild and two severe cases 81 were transferred to other hospitals after hospitalization in these two hospitals were detection limit of real time RT-PCR (1.7 ~6.0 ×10 3 copies/ml). In sputum ( Figure 1C) somehow higher than that in upper respiratory tract samples, and reached to 5.6×10 7 135 copies/ml in peak level at 1 st week after illness onset, but declined to 1.6 ×10 3 copies/ml 136 within 2~3 weeks. Viraemia was only detected in 1 of 7 severe cases, and sustained for 137 5~6 days ( Figure 1E ). Table 2 ). The dashed curve draws with experiential growth model and indicates the dynamic 259 tendency of antibodies. Each dot of ELISA presents as mean and standard deviation, 260 and titers of neutralizing antibodies present geometric mean and standard deviation.

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