Cross-Reaction of SARS-CoV Antigen with Autoantibodies in Autoimmune Diseases

Volume 1 Number 4 August 2004

Cross-Reaction of SARS-CoV Antigen with Autoantibodies in

Autoimmune Diseases

Yunshan Wang1, 2, 3, Shanhui Sun1, Hong Shen2, Lihua Jiang1, Maoxiu Zhang2, Dongjie Xiao1,

Yang Liu1, Xiaoli Ma1, Yong Zhang1, Nongjian Guo1 and Tanghong Jia2

To investigate the significance of the SARS-associated coronavirus (SARS-CoV) antibody, detected by ELISA

and indirect immunofluorescence assays (IFA) for the SARS-CoV Vero E6 cell lysates, in non-SARS subjects,

114 serum samples from healthy controls and 104 serum specimens from autoimmune disease patients were

collected. The results of ELISA showed that among 114 sera from healthy controls, 4 (3.5%) were positive of

SARS-CoV-IgG antibody and 114 (100%) were all negative of SARS-CoV-IgM antibody; the specificity of

SARS-CoV-IgG antibody for SARS patients was 96.5%, but the specificity of both SARS-CoV-IgG and -IgM

antibodies for SARS patients was 100%. In 58 cases with SLE, positive rates of SARS-CoV-IgG and -IgM

antibodies were 32.8% (19/58) and 8.6% (5/58), respectively, in which 11 cases (19%) were positive of both

SARS-CoV-IgG and -IgM antibodies; in 10 cases with SS, positive rate of both SARS-CoV-IgG and -IgM

antibodies was 10% (1/10); in 16 cases with MCTD, positive rate of SARS-CoV-IgG was 37.5% (6/16), positive

rate of both SARS-CoV-IgG and -IgM antibodies was 6.3% (1/16); in 20 cases with RA, one case was positive

(5%) of SARS-CoV-IgG. However, of all samples with positive SARS-CoV-IgG and -IgM antibodies for

autoimmune diseases and healthy controls, SARS-CoV RNA and antibodies were all negative by RT-PCR and

IFA. All sera for negative or positive ELISA results were also negative or positive results using ELISA with

Vero E6 cells lysates. These studies showed that SARS-CoV Vero E6 cell lysates for the ELISA to detect

SARS-CoV antibodies could lead to the false-positive reactions or cross-reactions of SARS-CoV antibodies in

non-SARS diseases and healthy controls, and the false-positive reactions or cross-reactions were related to Vero

E6 cell lysates and autoantibodies in non-SARS population. Cellular & Molecular Immunology. 2004;1(4):

304-307.

Key Words: SARS-CoV, autoimmune disease, cross-reaction

Introduction

Severe acute respiratory syndrome (SARS) has recently

emerged as a new human disease caused by SARSassociated

coronavirus (SARS-CoV) (1). So far, the

diagnosis of SARS is dependent upon clinical criteria,

epidemologic criteria, laboratory criteria and exclusion

criteria (2, 3). The identification of the SARS-CoV has led

to the development of serologic and virologic tests for the

disease. Laboratory diagnostic testings for evidence of

SARS-CoV infection include viral isolation, electron

microscopy, viral culture, SARS-CoV antibody, or reverse