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ARS Home » Research » Publications at this Location » Publication #65125
Title: RISK FACTORS FOR OVINE LENTIVIRUS SEROPOSITIVITY IN YEARLING REPLACEMENT SHEEP

Author
item Keen, James
item HUNGERFORD, LAURA - UNIVERSITY OF ILLINOIS
item LITTLEDIKE, E - OMAHA COL HLTH CAREERS
item WITTUM, THOMAS - OHIO STATE UNIVERSITY
item Kwang, Hwei Sing

Submitted to: Preventive Veterinary Medicine
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/17/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: Ovine lentivirus (OLV) is a slow onset viral infection of sheep which infects many U.S. flocks and which can have significant negative impacts on sheep production. Identification of risk factors associated with infection of sheep with this pathogen could result in improved management practices to control this virus in the U.S. In this study, a new enzyme immunoassay was used to detect OLV-infection among 220 ewes and their 328 yearling offspring from 7 flocks which had been selected as flock replacements. Increased risk of OLV infection in the replacements was associated with dam OLV infection (doubled risk) and difficult birth (tripled risk) while decreased risk was associated with artificial rearing in a lamb nursery. Yearling OLV risk also varied by flock, with Texel sheep at highest risk of yearling OLV infection. These findings point to the production period from birth until weaning as an important time of horizontal transmission from infected adults to noninfected offspring.

Technical Abstract: Recombinant ovine lentivirus (OLV) protein enzyme-linked immunosorbent assays (ELISAs) were used to detect anti-OLV antibodies in sera from 220 pregnant ewes in late gestation and from their 328 offspring (at 18 months of age) which were selected as flock replacement ewes and rams in order to determine their OLV infection status and its relationship with potential animal and management risk factors for OLV. Based on multiple logistic regression modeling, increased adjusted risk of OLV infection was associated with dam seropositivity [odds ratio (OR) = 2.0] and difficult birth (OR = 3.0) while decreased risk was associated with artificial rearing in a lamb nursery (OR = 0.44). Yearling risk also varied by flock, with Texel yearling at highest risk of yearling seropositivity. These results suggest the importance of the production period from birth until weaning as an important time of horizontal transmission from infected adults to non-infected offspring.