Volume 10, Number 11, November 2004

Nucleocapsid Protein as Early Diagnostic Marker for SARS

Xiao-Yan Che,* Wei Hao,* Yadi Wang,* Biao Di,† Kai Yin,* Yin-Chao Xu,* Chang-Sen Feng,* Zhuo-Yue Wan,‡ Vincent C.C. Cheng,§ and Kwok-Yung Yuen§
*First Military Medical University, Guangzhou, People's Republic of China; †Center for Disease Control and Prevention of Guangzhou, Guangzhou, People's Republic of China; ‡Center for Disease Control and Prevention of Guangdong Province, Guangzhou, People's Republic of China; and §The University of Hong Kong, Hong Kong Special Administrative Region, People's Republic of China

Figure 1. N protein detection in 420 serum samples from 317 patients with severe acute respiratory syndrome (SARS). Data represent the optical density at 450 nm (OD₄₅₀) of undiluted serum samples. To establish the normal range of the N protein–capture enzyme-linked immunosorbent assay, serum specimens from 400 healthy blood donors were analyzed. The mean OD₄₅₀ for these specimens, as determined by the assay, was 0.078, with a standard deviation of 0.023. The cutoff OD₄₅₀ of the assay was then calculated as follows: cutoff = mean of OD₄₅₀ from 400 normal serum + 5 x standard deviations = 0.19. Solid line represents cutoff value. The result was considered positive if a sample yielded OD₄₅₀ above the cutoff.

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This page last reviewed October 22, 2004

Emerging Infectious Diseases Journal
National Center for Infectious Diseases
Centers for Disease Control and Prevention