Oxford University Pressis collaborating with JSTOR to digitize, preserve and extend access toThe Journal of Infectious Diseases. http:/www.jstor.org Oxford University PressOxford University Press An Experimental Model for Myocarditis and Congestive Heart Failure after Rabbit Coronavirus Infection Author(s): Suzanne Edwards, J. David Small, Joachim Dieter Geratz, Lorraine K. Alexander and Ralph S. Baric Source: The Journal of Infectious Diseases,Vol. 165, No. 1 (Jan., 1992), pp. 134-140 Published by: Oxford University Press Stable URL: http:/www.jstor.org/stable/30112503 Accessed: 16-10-2015 19:20 UTC REFERENCESREFERENCES Linked references are available on JSTOR for this article: http:/www.jstor.org/stable/30112503?seq=1 however, considerable evidence suggests that the disease is primarily immune-mediated rather than the result of direct viral cytotoxicity to myocytes 12, 13. Both Coxsackie B and encephalomyocarditis virus infections in mice may progress to myocarditis and congestive heart failure, and some survi- Received 20 June 1991; revised 6 September 1991. Presented in part: International Coronavirus Symposium, Cambridge, UK, July 1989. Grant support: National Institutes of Health (AI-23946); American Heart Association (871135 and Established Investigator Award 890192 to R.S.B.). Reprints or correspondence: Dr. Ralph S. Baric, Department of Epidemi- ology, School of Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599-7400. The Journal of Infectious Diseases 1992;165:134-40 u 1992 by The University of Chicago. All rights reserved. 0022-1899/92/6501-0018$051.00 Materials and Methods Animals and virus. Rabbit coronavirus (RbCV) was origi- nally obtained from a stock maintained by one of the authors (J.D.S.). Viral stocks were diluted to 103-104 RID50/ml and stored at -1400C. Male New Zealand white rabbits (Franklin Rabbitry, Wake Forest, NC), weighing 2.5-3.0 kg, were housed at room temperature (21-24C) and given water and rabbit diet (Agway; Grandville Milling, Creedmoor, NC) ad libitum. The animals were inoculated intravenously via the marginal ear vein with 0.2 ml of the 103-104 RID50o viral stock. Body weight and rectal temperature were recorded daily. Animals were observed for signs of infection: dullness of the sclerae, severe congestion of the conjunctivae and irides, rectal temperatures 390C, and weight loss. To assay viral titers in the heart muscle, moribund animals were intravenously injected with 50 mg/kg sodium pentobarbi- tol, and the hearts were perfused and washed extensively with PBS. Two hundred micrograms of left ventricle were ground in 0.8 ml of PBS and centrifuged at 12,000 g for 10 min in an Eppendorf centrifuge (Fisher Scientific, Norcross, GA). The su- vors may progress to a dilated cardiomyopathy later in life 5, 14-16. The mechanisms by which viruses outside the entero- virus family cause heart disease are unclear. A model for virus-induced cardiomyopathy has also been described in rabbits 17. Rabbit cardiomyopathy is charac- terized by pulmonary edema, degeneration and necrosis of myocytes, and right ventricular dilation. Similar findings have also been reported in rabbits infected with pleural effu- sion disease virus 18, 19. The etiologic agent for rabbit cardiomyopathy is probably a rabbit coronavirus (RbCV) antigenically related to the human coronavirus strain 229E 17. We determined whether infection with RbCV would result in myocarditis and the development of congestive heart failure. This content downloaded from 137.207.120.173 on Fri, 16 Oct 2015 19:20:53 UTC All use subject to JSTOR Terms and Conditions JID 1992;165 (January) Coronavirus Myocarditis in Rabbits 135 pernatant was serially diluted and inoculated into the marginal ear vein of rabbits. Histologic studies. Animals dying from RbCV infection were necropsied within 12 h of death. Alternatively, moribund ani- mals were sacrificed as described above. Body weights were ob- tained to the nearest 0.10 kg. The heart was separated from the pericardial sac, trimmed of fat and extraneous tissue, and flushed with PBS. The heart was weighed to the nearest 0.1 g; the chambers were filled with 10% phosphate-buffered formalin (BF) and immersed in 10% BF for 24-48 h. The heart was re- moved and sectioned transversely at the widest dimensions of the ventricles. After additional fixation in BF, four paraffin-em- bedded 6-jum sections were cut at 150-lm intervals and stained with hematoxylin-eosin (H 37% subacute) (figure 1). Animals dying early from infection had enlarged hearts characterized by striking dilation of the right ventricular cav- ity and accompanied by pulmonary edema. Pleural effusion and congestion of the lungs and liver were occasionally pres- ent during the acute phase but were more commonly ob- served between days 6-9 after infect