Shedding of ovine herpesvirus 2 in sheep nasal secretions: the predominant mode for transmission.
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, short-lived, peak of viral DNA, ranging from 10(5) to over 10(8) copies/2 microg of DNA, was detected in nasal secretions from over 60.7% of adolescent sheep (n = 56) at some point during the period from 6 to 9 months of age. In contrast, only about 18% of adult sheep (n = 33) experienced a shedding episode during the study period. The general pattern of the appearance of viral DNA in nasal secretions was a dramatic rise and subsequent fall within 24 to 36 h, implying a single cycle of viral replication. These episodes occurred sporadically and infrequently, but over the 3-month period most of the 56 lambs (33, or 60.7%) experienced at least one episode. No corresponding fluctuations in DNA levels were found in either peripheral blood leukocytes or plasma. In a DNase protection assay, complete, enveloped OvHV-2 virions were demonstrated in the nasal secretions of all sheep examined during the time when they were experiencing an intense shedding episode. OvHV-2 infectivity in nasal secretions was also demonstrated by aerosolization of the secretions into OvHV-2-negative sheep. The data herein show that nasal shedding is the major mode of OvHV-2 transmission among domestic sheep and that adolescents represent the highest risk group for transmission.
Li
Hong
H
Animal Disease Research Unit, USDA Agricultural Research Service, 3003 ADBF, Washington State University, Pullman, WA 99164, USA. hli@vetmed.wsu.edu
Taus
Naomi S
NS
Lewis
Gregory S
GS
Kim
Okjin
O
Traul
Donald L
DL
Crawford
Timothy B
TB
D000818:Animals; D006566:Herpesviridae Infections / Q000635:transmission / Q000662:veterinary / Q000821:virology; D008304:Malignant Catarrh / Q000635:transmission* / Q000821:virology; D009297:Nasal Mucosa / Q000821:virology*; D018144:Rhadinovirus / Q000302:isolation & purification*; D012756:Sheep; D012757:Sheep Diseases / Q000635:transmission* / Q000821:virology; D014412:Tumor Virus Infections / Q000635:transmission / Q000662:veterinary / Q000821:virology; D017201:Virus Shedding