Cytoplasmic vacuolization responses to cytopathic bovine viral diarrhoea virus.
Bovine Viral Diarrhea Virus (BVDV) is a positive sense, single-stranded RNA virus which exhibits two biotypes in standard cell culture systems. The cytopathic strains of this virus (cpBVDV) induce dramatic cytoplasmic vacuolization in cell cultures, while infection with the non-cytopathic (NCP-BVDV) strains produces no overt changes in the host cells. Our results show that extensive cytoplasmic vacuolization is the earliest morphological change in response to cpBVDV infection in MDBK cells. Cells with extensive vacuolization showed no co-existing chromatin condensation, caspase activation, or loss of membrane integrity. In addition, the caspase inhibitor (zVAD-fmk), although improving cell viability of infected cells from 6.7+/-2.2% to 18.8+/-2.2%, did not prevent vacuolization. On the ultrastructural level, the virus-induced cytoplasmic vacuoles are single membrane structures containing organelles and cellular debris, which appear capable of fusing with other vacuoles and engulfing surrounding cytoplasmic materials. LysoTracker Red which marks lysosomes did not stain the virus-induced cytoplasmic vacuoles. In addition, this lysosomal dye could be observed in the cytoplasm of vacuolized cells, suggesting a lysosomal abnormality. Our data demonstrate that cpBVDV induced a novel cell death pathway in MDBK cells that is primarily associated with lysosomal dysfunction and the formation of phagocytic cytoplasmic vacuoles, and this mode of cell death is different from apoptosis and necrosis.
Department of Pharmacology, Weill Medical College of Cornell University, New York, NY 10021, USA. avbirk@ihvr.org
Alexander V
AV
Birk
Edward J
EJ
Dubovi
Leona
L
Cohen-Gould
Ruben
R
Donis
Hazel H
HH
Szeto
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D002417:Cattle; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D003588:Cytopathogenic Effect, Viral / Q000187:drug effects; D001908:Diarrhea Viruses, Bovine Viral / Q000502:physiology*; D008247:Lysosomes / Q000502:physiology / Q000821:virology; D008854:Microscopy, Electron; D014617:Vacuoles / Q000502:physiology / Q000648:ultrastructure / Q000821:virology*; D017361:Viral Nonstructural Proteins / Q000032:analysis / Q000378:metabolism
D000590:Amino Acid Chloromethyl Ketones; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D017361:Viral Nonstructural Proteins; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D020169:Caspases