By using a recombinant severe acute respiratory syndrome coronavirus (SARS-CoV) nucleocapsid protein-based enzyme-linked immunosorbent assay (ELISA) and serum specimens serially collected (from day 0 to day 240 after symptom onset) from patients with pneumonia due to SARS-CoV, we analyzed the longitudinal profiles of immunoglobulin G (IgG), IgM, and IgA antibodies against the SARS-CoV nucleocapsid protein in patients with pneumonia due to SARS-CoV. COL18A1 by indirect immunofluorescence assay were comparable. The median occasions of seroconversion for IgG, IgM, and IgA detected by the indirect immunofluorescence assay were 17 days (17 days by ELISA), 16.5 days (20.5 days by ELISA), and 17.5 days (17 days by ELISA), respectively, after disease onset. One, four, and one of the six patients who died did not produce any IgG, IgM, and IgA antibodies against the nucleocapsid protein of SARS-CoV, respectively, although these antibodies were detected in all Zanosar six patients by the indirect immunofluorescence assay. Further studies should be performed to find out whether SARS-CoV nucleocapsid proteins antibody positivity provides any prognostic significance. Serious acute respiratory symptoms (SARS) provides affected 30 countries in five continents, with an increase of than 8,000 situations and 750 fatalities. A novel pathogen, the SARS coronavirus (SARS-CoV), continues to be confirmed to end up being the etiological agent, and its own genome continues to be sequenced (4, 6-8). Lately, SARS-CoV-like viruses have already been isolated from Himalayan hand civets within a live pet marketplace in Guangdong Province of China (3). This acquiring implies that pets may be the tank for the ancestor of SARS-CoV. For the recognition of antibodies against SARS-CoV, at the brief moment, the hottest strategies are antibody recognition in severe- and convalescent-phase sera by indirect immunofluorescence assay and enzyme-linked immunosorbent assay (ELISA) with cell lifestyle ingredients (4, 7). Nevertheless, antibody recognition by indirect immunofluorescence ELISA and assay with cell lifestyle ingredients could be much less reproducible, more challenging to standardize, and even more Zanosar labor-intensive than ELISA-based antibody recognition exams with recombinant antigens. Furthermore, creation from the contaminated cell lines utilized to layer the ELISA plates as well as the slides for indirect immunofluorescence needs cultivation from the SARS-CoV, that biosafety level 3 lab facilities are needed. Such facilities aren’t obtainable in most scientific microbiology laboratories. ELISA-based antibody recognition exams with recombinant antigens are popular to provide higher reproducibilities, are simpler to standardize, and so are much less labor-intensive than antibody recognition by indirect immunofluorescence assay and ELISA with cell lifestyle extracts , nor need cultivation of SARS-CoV (1, 2, 9, 12). Lately, investigators have got reported on the usage of recombinant SARS-CoV nucleocapsid proteins ELISA-based antibody exams for serodiagnosis of SARS-CoV pneumonia and research from the seroprevalence of nonpneumonic SARS-CoV attacks (10, 11). In the analysis referred to in this article, using serially collected serum specimens from patients with SARS-CoV pneumonia, we analyzed the longitudinal profile of immunoglobulin G (IgG), IgM, and IgA antibodies against the SARS-CoV nucleocapsid protein in patients with pneumonia due to SARS-CoV. Zanosar The time of seroconversion detected by the recombinant SARS-CoV nucleocapsid protein-based ELISA and that Zanosar detected by indirect immunofluorescence assay were also compared. MATERIALS AND METHODS ELISA for detection of IgG, IgM, and IgA antibodies against nucleocapsid protein of SARS-CoV. The methods for the cloning and purification of His6-tagged recombinant nucleocapsid protein and optimization of the ELISA for detection of IgG, IgM, and IgA against SARS-CoV were reported previously (10, 11). ELISA was performed as described previously (10, 11). Briefly, each well of an immunoplate (Nunc, Roskilde, Denmark) was coated with purified His6-tagged recombinant nucleocapsid protein (20 ng for IgG.