Vaccination as a Strategy to Prevent Bluetongue Virus Vertical Transmission

Abstract

Bluetongue virus (BTV) produces an economically important disease in ruminants of compulsory notification to the OIE. BTV is typically transmitted by the bite of Culicoides spp., however, some BTV strains can be transmitted vertically, and this is associated with fetus malformations and abortions. The viral factors associated with the virus potency to cross the placental barrier are not well defined. The potency of vertical transmission is retained and sometimes even increased in live attenuated BTV vaccine strains. Because BTV possesses a segmented genome, the possibility of reassortment of vaccination strains with wild-type virus could even favor the transmission of this phenotype. In the present review, we will describe the non-vector-based BTV infection routes and discuss the experimental vaccination strategies that offer advantages over this drawback of some live attenuated BTV vaccines.

Clinical presentation, medical management, and outcomes in 35 hospitalized sheep diagnosed with bluetongue virus disease

“…BTV has a high affinity for erythrocytes, 30 but its target cells are endothelial cells, 31 resulting in endothelial damage, vasculitis, edema, and hemorrhage. Pyrexia and anorexia are considered early clinical signs of BTV disease, whereas respiratory distress and esophageal paralysis are considered severe forms of BTV disease 13 . In our study, 71% of sheep exhibited respiratory disease signs, which prompted owners to seek veterinary care.…”

“…[9][10][11] Disease severity depends on the strain of BTV, with sheep being the most susceptible ruminant species. 12,13 European fine wool and mutton sheep are more susceptible to BTV infections than indigenous breeds, 14 and Hartline/Suffolk crossbred sheep are more susceptible than purebred Hartline sheep. 15 Clinical signs of BTV disease include pyrexia, nasal discharge, congestion of nasal, oral, and ocular mucosa, facial edema, severe mucosal erosions, respiratory distress, coronitis and lameness, cyanosis of the tongue (blue tongue), abortion, and death.…”

“…At least 28 distinct serotypes of BTV were described, and multiple putative serotypes have been identified in addition since 2014 9‐11 . Disease severity depends on the strain of BTV, with sheep being the most susceptible ruminant species 12,13 . European fine wool and mutton sheep are more susceptible to BTV infections than indigenous breeds, 14 and Hartline/Suffolk crossbred sheep are more susceptible than purebred Hartline sheep 15 .…”

“…European fine wool and mutton sheep are more susceptible to BTV infections than indigenous breeds, 14 and Hartline/Suffolk crossbred sheep are more susceptible than purebred Hartline sheep 15 . Clinical signs of BTV disease include pyrexia, nasal discharge, congestion of nasal, oral, and ocular mucosa, facial edema, severe mucosal erosions, respiratory distress, coronitis and lameness, cyanosis of the tongue (blue tongue), abortion, and death 12,13 . Costs associated with BTV disease include treatment, death, abortions, decreased weight gain, control measures, and trade restrictions 16 .…”

An ABM of biting midge dynamics to understand Bluetongue outbreaks

“…With the large number of serotypes, each with varying virulence, it is difficult or impossible to vaccinate livestock against all strains (Noad and Roy [2009]). In addition, recent studies have shown that, due to the segmented genome of BTV, the use of live attenuated viruses to vaccinate ruminants has the possibility of introducing new genetic material to environments, increasing the risk of creating new BTV serotypes (Rojas et al [2021]).…”