title: Long-term infection of goats with bluetongue virus serotype 25.
abstract: Toggenburg Orbivirus (TOV) is the prototype of bluetongue virus serotype 25 (BTV-25). It was first detected in goats in Switzerland in 2008. The virus does not induce clinical signs in infected goats. In field samples viral RNA could be detected only in goats and never in other ruminants. BTV-25 RNA was repeatedly detected for more than one year in the blood of goats from a single flock in Principality of Liechtenstein. Since viral persistence over such a long period has never been reported for bluetongue, blood samples from 110 goats and 2 sheep of that flock were collected during a period of up to two years and analyzed for the presence of BTV-25 RNA and antibodies. Most of the animals which tested positive for BTV-25 RNA, remained positive during the whole investigation period. Moreover, five of these goats were BTV-25 RNA positive over a period of 19-25 months. A weak antibody response against BTV VP7 was commonly observed. As BTV-25 cannot be propagated in any culture system, the presence of virus could only be demonstrated in samples by viral RNA detection using RT-qPCR. To address the question of infectivity of the virus in blood from long-term positive animals, goats were experimentally infected with this blood. Viral replication was demonstrated by increasing RNA amounts. Thus, our findings provide evidence that BTV-25 can persist much longer in an infected host than known so far for other BTV serotypes. Hence, persistence of infectious BTV represents an additional important factor in BTV epidemiology.
authors.affiliation: Institute of Virology and Immunology (IVI), Sensemattstrasse 293, CH-3147 Mittelhäusern, Switzerland.
authors.forename: Andrea
authors.initials: A
authors.lastname: Vögtlin
authors.forename: Martin A
authors.initials: MA
authors.lastname: Hofmann
authors.forename: Christoph
authors.initials: C
authors.lastname: Nenniger
authors.forename: Sandra
authors.initials: S
authors.lastname: Renzullo
authors.forename: Adolf
authors.initials: A
authors.lastname: Steinrigl
authors.forename: Angelika
authors.initials: A
authors.lastname: Loitsch
authors.forename: Heinzpeter
authors.initials: H
authors.lastname: Schwermer
authors.forename: Christian
authors.initials: C
authors.lastname: Kaufmann
authors.forename: Barbara
authors.initials: B
authors.lastname: Thür
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000276:immunology; D001819:Bluetongue / Q000276:immunology / Q000821:virology*; D001820:Bluetongue virus / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification / Q000502:physiology*; D015511:Goat Diseases / Q000276:immunology / Q000821:virology*; D006041:Goats; D060888:Real-Time Polymerase Chain Reaction; D012756:Sheep; D012757:Sheep Diseases / Q000276:immunology / Q000821:virology; D013557:Switzerland
chemical_list: D000914:Antibodies, Viral
keywords: Bluetongue virus serotype 25; Goat; Persistent infection; Toggenburg Orbivirus