|Crawford, T - WASHINGTON STATE UNIV.|
Submitted to: American Society for Virology Meeting
Publication Type: Abstract Only
Publication Acceptance Date: April 7, 2003
Publication Date: July 13, 2003
Citation: Li, H., Kim O., Lewis, G.S., Crawford, T.B. Shedding of ovine herpesvirus 2 in sheep nasal secretions: the predominant mode of transmission. The 22nd Annual Meeting of American Society for Virology. 2003. Abstract. p. 247. Technical Abstract: Ovine herpesvirus 2 (OvHV-2), the major causative agent of malignant catarrhal fever in ruminant species worldwide, has never been propagated in vitro. Using real-time PCR, a striking peak of viral genomic copies, ranging from 100,000 to over 100,000,000 copies/2 ug DNA, was detected in nasal secretions from over 60% of adolescent sheep (n = 41) aged 6 to 9 months. Only about 4% of adult sheep (n = 26) experienced a shedding episode during the study period. The level of viral DNA in nasal secretions in the majority of individual sheep dramatically changed within 24 hrs, implying that the viral replication in the respiratory system is simply a single-cycle. No correlation was found between shedding peaks in nasal secretions and the level of viral DNA in either peripheral blood leukocytes or plasma of individual sheep. Using a DNase protection strategy, complete, enveloped OvHV-2 virions were demonstrated in the nasal secretion samples of all sheep examined which were experiencing an intense shedding episode. OvHV-2 infectivity in these nasal secretions was also demonstrated by aerosolization of the secretions into OvHV-2 negative sheep. Dexamethasone treatment failed to induce the shedding episodes. The data strongly indicate that nasal shedding is the major mode of OvHV-2 transmission among domestic sheep and that the adolescents are the highest risk group for transmission.