Canine coronavirus induces apoptosis in cultured cells.
Canine coronavirus (CCoV) is widespread in dogs in several countries and causes mild enteric illness evolving to severe enteritis in young pups. In in vitro cultures canine coronaviruses generally induce extensive cell death, however nature of the events leading to cell death remains largely unknown. We analysed the induction of cytopathic effect by CCoV in a canine fibrosarcoma cell line (A-72) in order to characterize the apoptotic effect in homologous cell system. Following CCoV infection A-72 cell line, which is permissive to CCoV, showed reduced growth rate, as detected by MTT assay, a standard colorimetric assay for measuring cellular proliferation, and underwent to apoptotic death. Starting from 24h after CCoV infection, cells morphology appeared dramatically changed, with cells rounding and detachment from culture surface. Morphologic and biochemical features of apoptosis, such as blebbing of the plasma membrane, translocation of phosphatidilserine to cell surface and annexin V positive staining, nuclear fragmentation, apoptotic bodies formation and DNA laddering, were detected in CCoV-infected cells. Propidium iodide staining of infected culture indicated the appearance of hypodiploid DNA peak corresponding to apoptotic cell population. Commonly to other animal coronavirus infection caspase-3 is likely to contribute to the execution phase of apoptosis induced by CCoV in A-72 cells since we found activation of enzymatic activity as well as procaspase-3 activating cleavage. Apoptotic death of infected cells is detrimental as it causes cell and tissue destruction as well as inflammatory responses. Therefore in the case of CCoV associated gastroenteritis, apoptosis of epithelial mucosa cells may be responsible for pathology induced by CCoV infection.
Ruggieri
A
A
Department of Infectious, Parasitic and Immune-mediated Diseases, Istituto Superiore Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
Di Trani
L
L
Gatto
I
I
Franco
M
M
Vignolo
E
E
Bedini
B
B
Elia
G
G
Buonavoglia
C
C
D000590:Amino Acid Chloromethyl Ketones / Q000494:pharmacology; D000818:Animals; D017304:Annexin A5 / Q000737:chemistry; D017209:Apoptosis / Q000502:physiology*; D015153:Blotting, Western / Q000662:veterinary; D053148:Caspase 3 / Q000378:metabolism; D061945:Caspase Inhibitors; D048708:Cell Growth Processes / Q000502:physiology; D045744:Cell Line, Tumor; D018352:Coronavirus Infections / Q000201:enzymology / Q000473:pathology / Q000662:veterinary* / Q000821:virology; D017939:Coronavirus, Canine / Q000502:physiology*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D003588:Cytopathogenic Effect, Viral; D053938:DNA Fragmentation; D004283:Dog Diseases / Q000473:pathology / Q000821:virology*; D004285:Dogs; D004789:Enzyme Activation; D005434:Flow Cytometry / Q000662:veterinary; D005456:Fluorescent Dyes / Q000737:chemistry; D005759:Gastroenteritis / Q000473:pathology / Q000662:veterinary* / Q000821:virology; D008858:Microscopy, Phase-Contrast / Q000662:veterinary; D011419:Propidium / Q000737:chemistry
D000590:Amino Acid Chloromethyl Ketones; D017304:Annexin A5; D061945:Caspase Inhibitors; D015853:Cysteine Proteinase Inhibitors; D005456:Fluorescent Dyes; C096713:benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone; D011419:Propidium; D053148:Caspase 3