Murine polyomavirus infection of 3T6 mouse cells shows evidence of predominant necrosis as well as limited apoptosis

The current study was developed to determine if polyomavirus infected 3T6 m ouse cells evoked an apoptotic or a necrotic mechanism during infection. In fected cells were analyzed by flow cytometry, transmission electron microsc opy (TEM), DNA electrophoresis and by measuring caspase-3 enzymatic activit y. Infected cells that were analyzed at 72 h post-infection showed the foll owing: flow cytometry analysis revealed a 5% increase in apoptotic cells an d a 46% increase in necrotic cells when compared to uninfected cells; elect ron microscopy showed 10% cells with characteristic apoptotic morphology an d 40% with necrotic appearance; caspase-3 activity was found to increase tw o fold when compared to uninfected cells and DMA fragmentation (laddering) was clearly evident late in infection. It was concluded that infected cells predominantly showed necrosis, although some cells showed apoptosis in lat e infection. Recombinant capsid-like particles composed of the polyomavirus structural proteins were not able to induce cell death. (C) 2000 Elsevier Science B.V. All rights reserved.