Introduction
A new strain of coronavirus (CoV) caused a pandemic outbreak of severe acute respiratory syndrome (SARS) in China, Hong Kong, Singapore, Toronto, and Taiwan from 2002 to 2003, resulting in 8098 individuals being infected and 774 deaths (1). As compared to other upper viral respiratory infections (2), SARS-CoV can rapidly induce pneumonia. The accompanying adult respiratory distress syndrome can quickly progress resulting in rapid death of the patients (3,4). The most commonly used laboratory diagnostic tests for SARS-CoV-infection are reverse transcription (RT)-PCR and anti-SARS-CoV antibody serological tests (5–7), but their roles in monitoring the extent of pneumonia are rather limited. Although, serial chest radiography is helpful for monitoring the progress of disease (8,9), it is also limited by its subjectivity and variability in the interpretation of the imaging results and occasionally suboptimal quality of portable films taken in isolation ward to avoid the spread of the disease. In a recent article, the discovery of 12 up-or downregulated serum biomarkers were reported in SARS patients by a novel protein chip array profiling approach (10–14) with one biomarker appears to be useful in monitoring the extent of pneumonia (15). In this chapter, how this protein chip array profiling technique is carried out is described. The technique involves four steps with the first step being serum fractionation in ceramic ion exchange sorbent beads. This step separates serum proteins into several fractions aiming at reducing their complexity before protein chip profiling is performed. The second step involves the binding of serum protein biomarkers onto protein chip array surfaces. The third step is desorption of bound serum biomarkers by laser shots in the mass spectrometer generating a time of flight spectrum for each sample. The fourth step concerns with data acquisition, data processing and statistical analyses of the spectra in SARS patients in comparison with the control groups. These procedures will be described in full details in the following chapter and summarized in the flow chart diagram as in Fig. 1.
Fig. 1. Sample fractionation, chip binding, and reading in protein chip array profiling technique. Serum samples from SARS patients and various control groups were fractionated in Q Ceramic Hyper D F anion exchange sorbent beads. The eluted fractions were in turn spotted onto two types of protein chips, namely, copper IMAC30 Cu(II) ProteinChip array and weak cation-exchange (CM10) ProteinChip array. Each sample bound protein chip was in turn inserted into a Protein Biology System II SELDI-TOF-mass spectrometer and the protein biomarkers were ionized and desorbed by laser beam. The ions flied to the ion detector generating a biomarker peak intensity spectrum according to their mass over charge values (m/z).