Morphological changes contribute to apoptotic cell death and are affected by caspase-3 and caspase-6 inhibitors during red sea bream iridovirus permissive replication

Abstract

Red sea bream iridovirus (RSIV) of the Iridoviridae family is a causative agent of lethal infections in many cultured marine fish species in southwestern Japan. RSIV-induced apoptosis was divided as follows: (1). cell shrinkage and rounding at the early apoptotic stage, (2). cell enlargement at the middle apoptotic stage, (3). formation of apoptotic body-like vesicles at the late apoptotic stage and phagocytosis by neighboring cells, and (4). loss of membrane integrity in apoptotic body-like vesicles without phagocytosis by neighboring cells. By affinity labeling, RSIV-induced apoptosis included caspase-dependent apoptosis. RSIV infection caused cell rounding but not cell enlargement or formation of apoptotic body-like vesicles and further restricted part of the structural protein synthesis in the presence of caspase-3 and -6 inhibitors. These findings showed the involvement of caspase-3 and -6 in the morphological changes at the middle and late apoptotic stages and viral protein synthesis in the late stage of RSIV infection.

Cloning of a new fibroblast cell line from an early primary culture from mandarin fish (Siniperca chuatsi) fry for efficient proliferation of megalocytiviruses

“…The yielded viral suspensions were still highly infectious to the MFF-8C1 cells. Unique CPEs characterized by cell shrinkage, rounding, enlargement, and breakage were also observed, which are highly consistent with previous descriptions of permissive cell infections with megalocytiviruses (Dong et al 2008(Dong et al , 2010Imajoh et al 2004Imajoh et al , 2007. After several continuous viral passages in MFF-8C1, the viral titers stabilized.…”

“…However, persistent high infectivity only occurred in a small number of cell lines, which are mainly represented by GF, CRF-1, and MFF-1 (Dong et al 2008(Dong et al , 2010Imajoh et al 2004Imajoh et al , 2007. In non-permissive and low permissive cell lines, viral infectivity always declined dramatically after no more than 3 rounds of viral passages.…”

“…Megalocytivirus infection always results in unique CPE changes in infected cells, which are characterized by cell rounding and enlargement (Dong et al 2008(Dong et al , 2010Imajoh et al 2004Imajoh et al , 2007Nakajima and Sorimachi 1994). However, persistent high infectivity only occurred in a small number of cell lines, which are mainly represented by GF, CRF-1, and MFF-1 (Dong et al 2008(Dong et al , 2010Imajoh et al 2004Imajoh et al , 2007.…”

Mitochondrion-mediated apoptosis induced by Rana grylio virus infection in fish cells

“…In this study, the RGVinfected cells display characteristic morphological and biochemical hallmarks of apoptosis, such as nuclear chromatin condensation, DNA fragmentation and formation of apoptotic bodies, suggesting that RGV-induced cell death should be mediated by apoptosis. Previously, some other members in family Iridoviridae, such as epizootic hematopoietic necrosis virus (EHNV), frog virus 3 (FV3), lymphocystis disease virus (LCDV) and red sea bream iridovirus (RSIV), were also proved to induce typical apoptosis during in vitro infection [14,[22][23][24].…”

Fine Structural Analysis of Unproductive and Lowproductive Cells Resulting on Cultured Rsiv (In Vitro)

“…Megalocytivirus has been known to be cultivated in some cultured cell (in vivo) such as BF-2 (bluegill fry-2), GF (grunt fin), CHSE-214, FHM, JSKG, KRE-3, KRE (a hybrid of kelp and red spotted grouper embryo), RTG-2 and YTF cell lines (Nakajima & Sorimachi, 1994;Imajoh et al, 2004;Chou et al, 1998). However, BF-2, GF and KRE cell lines were demonstrated to be optimal for Megalocytivirus infection and proliferation (Nakajima & Sorimachi, 1994;Imajoh et al, 2004;Mahardika & Miyazaki, 2009).…”