Expression and functional characterization of the putative protein 8b of the severe acute respiratory syndrome-associated coronavirus.

SARS 8b is one of the putative accessory proteins of the severe acute respiratory syndrome-associated coronavirus (SARS-CoV) with unknown functions. In this study, the cellular localization and activity of this estimated 9.6 kDa protein were examined. Confocal microscopy results indicated that SARS 8b is localized in both nucleus and cytoplasm of mammalian cells. Functional study revealed that overexpression of SARS 8b induced DNA synthesis. Coexpression of SARS 8b and SARS 6, a previously characterized SARS-CoV accessory protein, did not elicit synergistic effects on DNA synthesis.