mechanisms by which viruses make cytopathic effects within their sponsor cells

mechanisms by which viruses make cytopathic effects within their sponsor cells aren’t good understood. immunodeficiency pathogen human being T-cell leukemia virus influenza virus measles virus rubella virus poliovirus human herpesvirus 6 Sindbis virus and reoviruses cause cytopathic effect by induction of apoptosis in their target cells (11 14 21 34 40 42 50 70 We have used reovirus-induced apoptosis as an experimental model system to study the viral and cellular mechanisms involved in apoptotic cell death (39). Reoviruses are nonenveloped viruses that contain a genome of segmented double-stranded RNA. Contamination of cultured fibroblasts and epithelial cells with reoviruses induces apoptosis. Reoviral strains differ in the efficiencies with which they induce this cellular response and these differences are determined by the viral S1 gene (44 69 Apoptosis also occurs following reovirus contamination in vivo and colocalizes with areas of pathologic injury (38 39 This obtaining suggests that apoptosis is an important mechanism of tissue damage in reoviral contamination. Reovirus strain 8B is a reassortant reovirus that efficiently produces myocarditis in infected neonatal mice (55 58 Damage has been shown to be a direct effect of viral contamination of myocardiocytes (60). This damage differs from that of several other models of viral myocarditis (such as coxsackievirus and murine cytomegalovirus) in which secondary inflammatory responses or lymphocyte recognition of viral or self-antigens on myocardial cells may be the predominant cause of cardiac damage (12 17 20 30 46 SCID mice infected with reovirus 8B develop myocarditis and passive transfer of reovirus-specific immune cells is protective rather than harmful to 8B-infected mice (58 60 This obtaining indicates that immune mechanisms contribute to amelioration rather than induction of reovirus-induced viral injury (60). However the mechanism 726169-73-9 supplier by which direct myocardial injury occurs is not 726169-73-9 supplier well characterized. Since tissue damage occurs by apoptosis in other in vivo models of reoviral contamination (38) and apoptosis has been Rabbit Polyclonal to RPS11. suggested in some models of viral myocarditis (6 25 we wished to determine if reoviral myocarditis occurs as a result of apoptotic cell injury and if so whether manipulation of known signaling pathways preceding apoptosis is usually protective. Protease cascades appear to play critical roles as effectors of apoptosis as with the cysteine proteases caspases and calpain (10 32 41 62 79 Caspases are the most extensively investigated members of this class of protease and have been implicated in a wide variety of apoptotic models. However the role of calpain in apoptosis has been recognized 726169-73-9 supplier recently. Calpain is a calcium-dependent neutral cysteine protease that is ubiquitous in the cytosols of many cell types (35 63 Calpains have been recently implicated in a number of types of apoptosis including dexamethasone-induced thymocyte apoptosis (65) neuronal cell apoptosis (36) neutrophil apoptosis (64) ischemia-induced rat liver organ apoptosis (27 61 myonuclear apoptosis in limb-girdle dystrophy (3) and chemical substance hypoxia-induced apoptosis of rat myocytes (8). We’ve recently proven that reovirus-induced apoptosis in vitro is certainly preceded by elevated mobile calpain activity and it is inhibited by two classes of calpain inhibitors (13). We present that reovirus 8B-induced myocarditis occurs by apoptosis today. Calpain activity boosts in cardiomyocytes pursuing infections with reovirus 8B and calpain inhibition decreases myocardial damage and morbidity in contaminated mice. That is proof that disturbance with apoptotic signaling pathways may confirm of benefit being a healing strategy in the treating viral infections generally and viral myocarditis specifically. METHODS and materials Virus. Reovirus 8B can be an effectively myocarditic reovirus that is previously characterized (58). 8B shares were put through plaque assay 3 726169-73-9 supplier x and passaged 726169-73-9 supplier double in mouse L cells ahead of make use of. Mice. Swiss-Webster (Taconic) mouse litters had been housed in specific filter-topped cages within an American Association for Lab Animal Care-accredited pet facility. All pet procedures were performed under protocols approved by the appropriate institutional.