Bluetongue virus vaccine: conventional to modern approach.

Bluetongue (BT) is an economically important, infectious and non-contagious disease of ruminant animals. BT disease is caused by bluetongue virus (BTV) of the genus Orbivirus (the family Reoviridae). BTV is transmitted by certain species of biting midges of the genus Culicoides. Although originally BT was restricted to African continent, now it is present in all the continents except Antarctica. Conventional BT vaccines such as live attenuated and inactivated vaccines showed different degree of success in BT control. However, conventional vaccines have certain disadvantages of reversion to virulent strain and frequent booster dose requirement. Several BT outbreaks in India and the rest of the world open a new insight for development of better vaccines. The development in molecular biology techniques allowed the development and validation of several modern vaccines such as subunit vaccine, recombinant vector vaccine, disabled infections single cycle (DISC) vaccine, differentiating infected from vaccinated animals (DIVA) approach etc. Most of these vaccines are considered as safer, having better protective immune response and provided cross-protective immunization against more than one serotype. Keywords: bluetongue virus; live vaccine; inactivated vaccine; DISC; recombinant vaccine.