Synthetic peptide studies on the severe acute respiratory syndrome (SARS) coronavirus spike glycoprotein: perspective for SARS vaccine development.

BACKGROUND: The S (spike) protein of the etiologic coronavirus (CoV) agent of severe acute respiratory syndrome (SARS) plays a central role in mediating viral infection via receptor binding and membrane fusion between the virion and the host cell. We focused on using synthetic peptides for developing antibodies against SARS-CoV, which aimed to block viral invasion by eliciting an immune response specific to the native SARS-CoV S protein. METHODS: Six peptide sequences corresponding to the surface regions of SARS-CoV S protein were designed and investigated by use of combined bioinformatics and structural analysis. These synthetic peptides were used to immunize both rabbits and monkeys. Antisera collected 1 week after the second immunization were analyzed by ELISA and tested for antibody specificity against SARS-CoV by immunofluorescent confocal microscopy. RESULTS: Four of our six synthetic peptides (S2, S3, S5, and S6) elicited SARS-CoV-specific antibodies, of which S5 (residues 788-820) and S6 (residues 1002-1030) exhibited immunogenic responses similar to those found in a parallel investigation using truncated recombinant protein analogs of the SARS-CoV S protein. This suggested that our S5 and S6 peptides may represent two minimum biologically active sequences of the immunogenic regions of the SARS-CoV S protein. CONCLUSIONS: Synthetic peptides can elicit specific antibodies to SARS-CoV. The study provides insights for the future development of SARS vaccine via the synthetic-peptide-based approach.

Quantification of plasma beta-catenin mRNA in colorectal cancer and adenoma patients.

PURPOSE: Colorectal cancer is an important cause of cancer deaths. Here, we focused our investigation on the beta-catenin gene which is implicated in colorectal carcinogenesis and tested whether beta-catenin mRNA is detectable in the plasma of colorectal carcinoma and adenoma patients using quantitative reverse transcriptase-PCR. EXPERIMENTAL DESIGN: Plasma beta-catenin mRNA was measured from 58 colorectal carcinoma patients, 49 colorectal adenoma patients, and 43 apparently normal subjects using intron-spanning primers and Taqman probes. Five clinicopathological parameters were studied and correlated with plasma beta-catenin mRNA concentration. Additionally, 19 colorectal carcinoma patients after tumor removal were also recruited for plasma beta-catenin mRNA measurement to further demonstrate the clinical usefulness of this test. RESULTS: beta-catenin mRNA was detected with median concentrations of 8737 (range: 1480-933100), 1218 (range: 541-2254) and 291 (range: 0-1366) copies/ml plasma in colorectal carcinoma, colorectal adenoma, and apparently normal subjects, respectively. Statistical analysis demonstrated that plasma beta-catenin mRNA concentration was correlated to tumor stage but not sex, age, lymph node status, and degree in differentiation. Moreover, plasma beta-catenin mRNA concentration decreased significantly after tumor removal in 16 of 19 (84%) colorectal carcinoma patients. CONCLUSIONS: We conclude that plasma beta-catenin mRNA may potentially serve as a marker for colorectal cancer.