Coxsackievirus B3 induces apoptosis in the early phase of murine myocarditis: a comparative analysis of cardiovirulent and noncardiovirulent strains.
OBJECTIVE
To investigate the relationship between enteroviral infection and myocardial tissue apoptosis during the development of viral myocarditis in a murine model.


METHODS
C3H/HeJ mice were inoculated with two strains of coxsackievirus B3, specifically CVB3 (cardiovirulent Nancy strain) and CVB3/0 (noncardiovirulent strain). Mice were sacrificed at 4, 7 and 10 days postinfection (p.i.). Hearts were removed, and plaque assays and RT-PCR were performed to detect the presence of viruses. Myocardial tissue sections were additionally evaluated by hematoxylin and eosin staining for inflammation, VP1 and Bax immunohistochemical staining for detection of virus and Bax expression, and TUNEL and Apostain for localization of apoptosis.


RESULTS
CVB3 replicated to significantly higher titers than CVB3/0 at all time points. Histopathological analyses revealed significant inflammatory changes at all time points in CVB3-infected mice, in contrast to minimal changes in CVB3/0-infected mice. TUNEL and Apostain assays of myocardial tissues from mice infected with CVB3 disclosed maximum apoptotic lesions at 4 days p.i. and to a lesser extent at 7 and 10 days p.i. Moreover, CVB3-infected myocardial tissues displayed significantly enhanced Bax expression at 4 days p.i., and lesions overlapped with VP1-stained areas.


CONCLUSIONS
These data indicate that (1) the cardiovirulent strain CVB3 induces more severe inflammation and apoptosis than the noncardiovirulent CVB3/0 strain, (2) viral replication is localized in inflammatory and apoptotic lesions in myocardial tissues, (3) apoptotic changes are observed in the early stages of myocarditis and (4) Bax may be associated with the apoptosis process in CVB3-induced myocarditis.
Joo
Chul Hyun
CH
Department of Microbiology, University of Ulsan College of Medicine, Seoul, Korea.
Hong
Hea Nam
HN
Kim
Eun Ok
EO
Im
Jin Ok
JO
Yoon
Seung-Yong
SY
Ye
Jeong Sook
JS
Moon
Mi Sun
MS
Kim
Donghou
D
Lee
Heuiran
H
Kim
Yoo Kyum
YK
D000818:Animals; D017209:Apoptosis; D004195:Disease Models, Animal; D029822:Enterovirus B, Human / Q000235:genetics / Q000302:isolation & purification / Q000472:pathogenicity*; D004769:Enterovirus Infections / Q000473:pathology / Q000821:virology; D006801:Humans; D051379:Mice; D008809:Mice, Inbred C3H; D009205:Myocarditis / Q000473:pathology* / Q000821:virology; D009206:Myocardium / Q000473:pathology*; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013997:Time Factors; D010948:Viral Plaque Assay; D051028:bcl-2-Associated X Protein
C494826:BAX protein, human; C494827:Bax protein, mouse; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D051028:bcl-2-Associated X Protein