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→Vaccination
===Vaccination===
===Vaccination===
Vaccines against bluetongue are available. Vaccination typically is used to prevent outbreaks of BT, and has also been used in an effort to control incursions of BTV. Only modified live BTV vaccines are in widespread use, particularly in Africa, the United States and, most recently, southern Europe. These vaccines have proven very useful in preventing losses attributable to BT, but they also suffer from a number of serious potential deficiencies that include: the introduction of novel virus strains into the environment, perhaps leading to infection of vector insects; quasispecies evolution with possible reversion to virulence or creation of new strains of BTV; reassortment of gene segments with indigenous viruses to generate potentially novel recombinants; fetal infection and teratogenesis. In fact, it is increasingly clear that only strains of BTV that have been modified by growth in cell culture, such as MLV vaccine strains, have the capacity to cross the ruminant placenta. Once MLV BTV strains cross the placenta they cause embryonic or fetal death, and cerebral malformations after infection of older fetuses that survive congenital infection [4,19,24]. New generation vaccines, such as the virus-like particles produced by baculovirus expression of different viral proteins [27], have not yet been used extensively perhaps because of their cost.
Vaccines against BTV are available, and in different situations may be used to prevent or control outbreaks of bluetongue. Initially, modified live BTV vaccines were used, particularly in Africa, the United States and southern Europe<sup></sup>. Although useful for the control of disease, these vaccines have the potential to introduce novel strains of virus into the environment, which could lead to vector infection and reversion to virulence by evolution or genome reassortment with wild-type viruses. Foetal infection and teratogenesis are also possible. Killed, adjuvanted vaccines for some serotypes are now available, and it is this type of product that has been used in the UK for the control of BTV-8 in recent years.
===Vector Control===
===Vector Control===