Impaired humoral immunity of COVID-19 patients with
re-detectable positive RNA test after recovery
Qing Lei1,2, Caizheng Yu3, Yang
Li4, Hongyan Hou5, Banga Ndzouboukou
Jo-Lewis1, Zhuqing Ouyang1, Yandi
Zhang1, Xiaosong Lin1, Zongjie
Yao1, Fu hui1, Ziyong
Sun5, Feng Wang5,*, Shengce
Tao4,*, Xionglin Fan1,*
1Department of Pathogen Biology, School of Basic
Medicine, Tongji Medical College, Huazhong University of Science and
Technology, Wuhan, China.
2Department of Medical Laboratory, The Central
Hospital of Wuhan, Tongji Medical College, Huazhong University of
Science and Technology, Wuhan, China.
3Department of Public Health, Tongji Hospital, Tongji
Medical College, Huazhong University of
Science and Technology, Wuhan, China.
4Shanghai Center for Systems Biomedicine, Key
Laboratory of Systems Biomedicine (Ministry of Education), Shanghai Jiao
Tong University, Shanghai 200240, China
5Department of Laboratory Medicine, Tongji Hospital,
Tongji Medical College, Huazhong University of Science and Technology,
Wuhan, China.
*Correspondence’ e-mail: Xiong-lin
Fan(xlfan@hust.edu.cn),
Sheng-ce
Tao(taosc@sjtu.edu.cn),
Feng Wang(fengwang@tjh.tjmu.edu.cn)
To the Editor,
The coronavirus disease 2019 (COVID-19), caused by severe acute
respiratory syndrome coronavirus 2 (SARS-CoV-2), has rapidly spread
worldwide.1,2As of May 28, 2020, WHO estimated that there had been 169 million
confirmed cases and 3.5 million patients died from SARS-CoV-2
infection.3 Due to lack
of etiological treatments, about 3.5%-18% of discharged COVID-19
patients after recovery had a re-tested positive result for SARS-CoV-2
RNA, who was also named after re-detectable positive patients
(RP).4-8 Moreover, RP
patients may have the potential for virus
transmission.9,10However, the mechanism of the occurrence of RP patients remains little
known.
Humoral immunity, especially neutralizing antibody plays an important
role in preventing against SARS-CoV-2 infection, and even disease
progression. To elucidate the role of humoral immunity in RP patients,
we compared anti-SARS-CoV-2 IgM and IgG antibody responses between RP
and non-RP patients in this study. 21 RP patients from Wuhan Pulmonary
Hospital (Wuhan, China) between Jan 11, 2020, and April 1,
20204 and 113 non-RP
patients discharged from Tongji Hospital, between February 17, 2020, and
April 28, 2020 were recruited. Non-RP had negative NAT results while RP
patients had at least once positive result during weekly follow-up after
discharge. The median time from discharge to a positive retest of 21 RP
patients was 14 (range: 4-24) days, and their serum samples were
collected at the time of the positive retest. Besides, the serum samples
of 113 non-RP patients were collected on the 14th day after discharge.
At the same time, we collected serum samples of 601 non-COVID-19
controls including healthy donors, lung cancer patients, patients with
autoimmune diseases from Ruijin Hospital (Shanghai, China), Tongren
Hospital (Shanghai, China), or National Institutes for Food and Drug
Control.11 All serum
samples were stored under -80oC until use.
First, we used a homemade proteome microarray to detect serum IgM (red)
or IgG (green) antibody responses against 20 out of 28 predicted
proteins of SARS-CoV-2 with Alexa Fluor 647-conjugated donkey anti-human
IgM and Cy3-conjugated goat anti-human IgG (Figure S1) , as
previously described. Based on the fluorescent intensity extracted from
the microarray, anti-SARS-CoV-2 IgM and IgG profiles for each serum
sample were established (Figure 1 ). Interestingly, there were
differential IgM and IgG profiles observed between RP patients and
non-RP patients. RP patients elicited lower levels of IgM and IgG
responses against NSP7, ORF3a, and ORF7b, as well as anti-S1 and N
specific IgM and IgG than non-RP patients (Figure 2 ). More
importantly, RP patients induced higher levels of specific IgG
antibodies against most non-structural and accessory proteins, such as
NSP1, NSP2, NSP4, NSP5, NSP7, NSP8, NSP9, NSP10, RdRp, NSP14, NSP15,
NSP16, ORF-3b, ORF6, and ORF9b, and E structural protein (Figure
2 ). Previously, the levels of IgG responses to NSP4, NSP7, NSP9, NSP10,
RdRp, NSP14 and ORF3 might be related with the poor prognosis and
severity of COVID-19.
Further, a pseudotyped virus-based neutralization assay platform was
used to detect the levels of serum nAb. Unexpectedly, RP patients
elicited lower levels of nAb than non-RP. In particular, 90.5% (19/21)
RP patients could not detect the nAb response (NT50<10)
(Figure S2 ).
In conclusion, RP patients impaired humoral immunity, which might
benefit the replication of residual SARS-CoV-2 virus in vivo. Our
findings have an important impact on improving clinical management. The
criterion for patients’ recovery and discharge should be improved to
prevent recurrence , such as serological detection and even nAb
response, besides persisting and repeated NAT screening.