Submitted to: Herpesvirus International Workshop
Publication Type: Abstract Only
Publication Acceptance Date: 4/6/2004
Publication Date: 7/26/2004
Citation: Taus, N.S., Traul, D., Oaks, J.L., Crawford, T.B., Lewis, G.S., Li, H. 2004. Dose dependent responses in sheep experimentally infected with ovhv-2 [abstract]. Herpesvirus International Workshop. p. 11.14
Technical Abstract: Ovine herpesvirus-2 (OvHV-2), a rhadinovirus, is the causative agent of sheep-associated malignant catarrhal fever in clinically susceptible ruminants, including cattle, bison, and deer. Recently we demonstrated the presence of OvHV-2 virions in nasal secretions from sheep (Kim, et al. 2003; Virus Research 98:117-122) and also demonstrated infectivity of nasal secretions collected from sheep during peak virus shedding episodes. This study was designed to determine the infectivity of and characterize the dose responses to a pool of nasal secretions collected from sheep during peak virus shedding. OvHV-2 negative sheep were nebulized with 2 ml of nasal secretions containing approximately 100,000,000 (n=2), 1,000,000 (n=2) and 10,000 (n=2) copies of OvHV-2 DNA. Control sheep (n=2) were nebulized with nasal secretions collected from OvHV-2 negative sheep. Blood and nasal secretion samples were collected daily from all sheep and examined with semi-nested and real-time PCR for viral DNA. Plasma was examined with cELISA for viral antibody. Beginning 7-12 days post exposure, OvHV-2 DNA was detected in peripheral blood leukocytes (PBL) from all sheep exposed to OvHV-2 positive secretions. Viral antibody was detected at 9-29 days post exposure. The time to detectable viral DNA in PBL and viral antibody in plasma were directly related to the dose of virus exposure. Control sheep remained negative for viral antibody and viral DNA. Studies of OvHV-2 have been hampered by the lack of an in vitro propagation system and a standardized means for infecting experimental animals. In this study, we have developed the first defined source of infectious OvHV-2 that can be used for further studies in animal models, including clinically susceptible ruminants.