Suppression of Epstein-Barr virus reactivation in lymphoblastoid cells cultured in simulated microgravity

Rotating-wall vessels allow for the growth of cells in simulated microgravi ty. Lymphoblastoid cells cultured in rotating wall vessels exhibited signif icant differences in the expression of both early and late Epstein-Barr Vir us (EBV) antigens. Viral protein expression (as measured by indirect immuno fluorescence) was significantly suppressed in cells cultured in simulated m icrogravity. A significantly greater percentage of P3HR-1 cells and Daudi c ells were positive for the expression of BamH1-Z-DNA fragment of Epstein-Ba rr replication activator (ZEBRA), early antigen restricted (EA-R), and vira l capsid antigen (VCA) in cells cultured in static tissue culture flasks as compared to cells cultured in rotating-wall vessels. We observed a 7, 11, and 25-fold reduction, respectively: for EA-R, VCA, and ZEBRA protein in P3 HR-1 cells cultured in simulated microgravity. Additionally, suspension cul tures of P3HR-1 cells exhibited significantly greater ZEBRA antigen express ion than cells cultured in rotating-wall vessels. As an independent confirm ation of the reduction in ZEBRA-protein production in simulated microgravit y in P3HR-1 cells, ZEBRA-mRNA was quantitated by reverse transcription poly merase chain reaction. We observed between a 4 to 10-fold reduction in ZEBR A-mRNA in cells cultured in simulated microgravity as compared to cells cul tured at 1 x g in tissue culture flasks. Rotating-wall vessels, by virtue o f providing a simple culture environment triggering marked differences in v iral activation, provide a model whereby both host and viral factors involv ed in regulating the maintenance of EBV latency can be examined.