[The application of indirect immuno-fluorescence assay in the diagnosis of severe acute respiratory syndrome].
OBJECTIVE
To explore the temporal profile of serum antibody against coronavirus in patients with severe acute respiratory syndrome (SARS), and to evaluate the reliability of indirect immuno-fluorescence assay (IFA) in the diagnosis of SARS.


METHODS
Clinically confirmed SARS patients, suspected SARS patients, and controls were included in the study. IFA was used to detect the serum antibody against SARS coronavirus. General information about the subjects was collected using a standard questionnaire.


RESULTS
The positive rates of specific IgG and IgM against SARS virus within 10 days after onset of the disease were 55.1% and 16.3% respectively and then increased up to 89.8% for IgG and 65.3% for IgM. After 25 days of the onset of the disease, 90.9% patients became positive for both IgG and IgM. Results from chi-square for trend test revealed that the positive rates of both IgG and IgM increased with time (chi(2) for trend = 16.376, P = 0.00005 for IgG; chi(2) for trend = 28.736, P = 0.00000 for IgM). Sensitivity, specificity and agreement value of IFA regarding the diagnosis of SARS were all higher than 90%.


CONCLUSIONS
IFA can be used to assist diagnosis of SARS after 10 days of the onset of disease.
Fang
Li-qun
LQ
Institute of Microbiology and Epidemiology, Academy of Military Medical Sciences, Beijing 100071, China.
Zhang
Pan-he
PH
Yang
Bao-an
BA
Wu
Xiao-ming
XM
Zhao
Qiu-min
QM
Liu
Wei
W
Liu
Hong
H
Deng
Yong-qiang
YQ
Zhan
Lin
L
Han
Wei-guo
WG
Lu
Fu-shuang
FS
Wu
Jin-song
JS
Yang
Hong
H
Zhu
Qing-yu
QY
Cao
Wu-chun
WC
D000914:Antibodies, Viral / Q000097:blood*; D004797:Enzyme-Linked Immunosorbent Assay; D019084:Fluorescent Antibody Technique, Indirect / Q000379:methods*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007075:Immunoglobulin M / Q000097:blood; D045473:Severe acute respiratory syndrome-related coronavirus / Q000276:immunology*; D045169:Severe Acute Respiratory Syndrome / Q000175:diagnosis*
D000914:Antibodies, Viral; D007074:Immunoglobulin G; D007075:Immunoglobulin M