Toggenburg Orbivirus, a new bluetongue virus: Initial detection, first observations in field and experimental infection of goats and sheep

Abstract

A novel bluetongue virus termed "Toggenburg Orbivirus" (TOV) was detected in two Swiss goat flocks. This orbivirus was characterized by sequencing of 7 of its 10 viral genome segments. The sequencing data revealed that this virus is likely to represent a new serotype of bluetongue virus [Hofmann, M.A., Renzullo, S., Mader, M., Chaignat, V., Worwa, G., Thuer, B., 2008b. Genetic characterization of Toggenburg Orbivirus (TOV) as a tentative 25th serotype of bluetongue virus, detected in goats from Switzerland. Emerg. Infect. Dis. 14, 1855-1861]. In the field, no clinical signs were observed in TOV-infected adult goats; however, several stillborn and weak born kids were reported. Although born during a period of extremely low vector activity, one of these kids was found to be antibody and viral genome positive and died 3.5 weeks postpartum. Experimental infection of goats and sheep, using TOV-positive field blood samples, was performed to assess the pathogenicity of this virus. Goats did not show any clinical or pathological signs, whereas in sheep mild bluetongue-like clinical signs were observed. Necropsy of sheep demonstrated bluetongue-typical hemorrhages in the wall of the pulmonary artery. Viral RNA was detected in organs, e.g. spleen, palatine tonsils, lung and several lymph nodes of three experimentally infected animals. Unlike other bluetongue virus serotypes, it was not possible to propagate the virus, either from naturally or experimentally infected animals in any of the tested mammalian or insect cell lines or in embryonated chicken eggs. In small ruminants, TOV leads to mild bluetongue-like symptoms. Further investigations about prevalence of this virus are needed to increase the knowledge on its epidemiology.

Transplacental infection in goats experimentally infected with a European strain of bluetongue virus serotype 8

“…Interestingly Chaignat et al, (2009) antibodies. The animal also demonstrated signs of central nervous system dysfunction and died a few weeks after birth .…”

Bluetongue in Europe and the role of wildlife in the epidemiology of disease

“…BT has a significant economic impact, mainly due to the disease effect on animals (morbidity, mortality, reproductive failure, reduction in milk yields and weight gain) and, most of all, to the disruption of international trade of animals and animal products (Saegerman et al 2008). Up-to-date 26 immunologically distinct serotypes of BTV have been identified worldwide (Schwartz-Cornil et al 2008, Chaignat et al 2009, Mann et al 2011. BTV is endemic in many tropical, sub-tropical and temperate regions of the world (America, Australia, Africa and some regions of Asia), between latitudes 40 o S and 53 o N, during times of the year that are optimal for vector activity (Mellor et al 2000).…”

Balance of RNA sequence requirement and NS3/NS3a expression of segment 10 of orbiviruses

“…5d, e). This suggests that NS3/ NS3a of BTV25 and 26 could be involved in the distinct characteristics of these new BTV serotypes (Batten et al, 2012(Batten et al, , 2014Chaignat et al, 2009;Planzer et al, 2011).…”

“…BTV25 or Toggenburg orbivirus was identified in asymptomatic infections in goats, but not in other wild or domestic ruminants (Casaubon et al, 2013;Chaignat et al, 2009). In goats, RNA was detected for a strikingly long period, whereas sheep showed minor symptoms and a very low viraemia in experimental infections (Vögtlin et al, 2013).…”