CDC involvement in SARS
• CDC Flu Branch became involved initially; Special Pathogens Branch became involved because of evidence of person-to-person transmission.
• Special Pathogens focused on obtaining diagnostic specimens in early days, working to identify specific diagnostic tests, the pathological process, possible agents, and tissues to focus on.
• Presence of giant cells in lung and diffuse alveolar damage suggested a viral etiology.
• Vero E6 cells were inoculated.
• Electron microscopy, negative stain, thin-section morphology, and morphogenesis resembled coronaviruses.
• Dean Erdman's group designed primers that can be used as a diagnostic technique on clinical materials.
• Sequence analysis suggests SARS virus is the first in a new group of coronaviruses.
• Cofactors still may be involved in causing SARS, but coronavirus is the etiologic agent.
• Antigens could not be found on giant cells from patients, but antigens usually do not persist for long in many respiratory infections.
• Vero E6 cells can be stained in an indirect fluorescent antibody (IFA) with convalescent patient serum, showing viral antigens present.
• An ELISA test was developed using antigens from infected cells.
• Western blot on convalescent patient materials show N protein predominates and is goal for recombinant protein synthesis.
• ELISA and IFA can be used on convalescent and acute sera from patients to show conversion from negative to positive.
SARS in Cultures and Tissues
• Virus sequences from various sites is essentially identical.
• The disease is reproduced in cynomolgus monkeys.
• Virus is identified in respiratory secretions and tissues using a number of techniques.
• Patients, including those who succumb, have neutralizing antibodies.