Antibody response correlates with severity of infection.

While increasing numbers of cytomegalovirus (CMV)-associated diseases are occurring in patients undergoing conventional chemotherapy, information regarding CMV reactivation is limited. This pilot study was conducted to investigate CMV reactivation induced by chemotherapy. Seven blood samples were collected from each of 15 patients with newly diagnosed malignant disease, at baseline before chemotherapy, and once every month after chemotherapy was commenced. CMV viral loads in leukocytes were determined by real-time PCR. Host responses to changes in viral loads were assessed by assaying CMV-specific IgG titres and tumour necrosis factor (TNF)-alpha and interferon (IFN)-gamma levels in each of the blood samples, and by scoring the number of CMV-associated clinical symptoms that developed. All except one patient experienced CMV reactivation during the course of chemotherapy, with the average viral load peaking after the third course of treatment. Titres of CMV-specific IgG increased in line with the increase in viral load. Plasma levels of TNF-alpha and IFN-gamma initially decreased from baseline, and then rose to peak levels at the same time as, or shortly after, the highest viral loads were recorded. Clinical symptoms potentially attributable to CMV infection appeared as the viral load increased. It was concluded that the incidence of CMV reactivation in patients receiving conventional chemotherapy is high. Reactivation is not asymptomatic, but was self-limiting in most of these cases. Increases in plasma TNF-alpha and IFN-gamma occur after reactivation, but not before.

None of the presenting symptoms or laboratory findings are pathognomonic for SARS. Even though cough developed in a majority of patients, it did not occur until later in the disease course, suggesting that a cough preceding or concurrent with the onset of fever is less likely to indicate SARS. While PCR for SARS-CoV appears to be the best early diagnostic test currently available, it is clear that better methods are needed to differentiate between SARS and non-SARS illness on initial presentation.

Early detection and identification of SARS-CoV-infected patients and actions to prevent transmission are absolutely critical to prevent another SARS outbreak. Antibodies that specifically recognize the SARS-CoV spike and nucleocapsid proteins may provide a rapid screening method to allow accurate identification and isolation of patients with the virus early in their infection. For this reason, we raised peptide-induced polyclonal antibodies against SARS-CoV spike protein and polyclonal antibodies against SARS-CoV nucleocapsid protein using 6x His nucleocapsid recombinant protein. Western blot analysis and immunofluorescent staining showed that these antibodies specifically recognized SARS-CoV.