Expression and formulation of Bluetongue virus genes and proteins for development of effective vaccination strategies

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Bluetongue virus (BTV) can infect all ruminants, including cows, sheep and goats, in most cases without causing disease. However, when the virus infects sheep, particularly the European breeds, it can cause severe disease, killing up to 70% of the infected animals. The virus is transmitted by biting midges (Culicoides species), particularly those species which prefer warmer climates. As a result of recent changes in the European climate that are thought to have been caused by global warming, midges that can transmit BTV are moving northwards. This places Europe at much greater risk from the disease than before. Indeed, since 1998, six different strains of BTV have invaded the Mediterranean region, on a total of seven different occassions, affecting all of the countries of Southern Europe and collectively causing the largest outbreak of the disease ever recorded (with over 1.5 million dead animals). The vaccines that are currently available to fight bluetongue are live strains of the bluetongue virus that have been weakened (attenuated) by growth for many generations in cell cultures. These are supposed to produce only mild symptoms but protect the animal from more dangerous virus strains. However, there is evidence that these vaccine strains are also dangerous, causing disease and being transmitted by the same biting midges as the wild type viruses. Alternative inactivated vaccines have recently become available, based on partially purified and chemically treated virus, although the nature of the response to these vaccines (protective or not) still has to be tested in the field. The bluetongue virus particle has an outer protein layer composed of two proteins, VP2 and VP5, and a core, with a surface composed of VP7, proteins which are recognised by the immune system of infected animals, generating a reponse that can protect against the disease. The project will make DNA copies of viral genes and use them to synthesise viral proteins in bacteria, or in insect cells. The proteins will then be purified and used to study their interactions with the animal's immune system, particularly the production of a protective response e.g. antibodies that can neutralise the virus. The project will also examine the structure of the outer surface proteins of BTV particles, to see which aminoacid sequences react with the immune system and lead to a neutralising response. The project will use DNA copies of the viral genes directly, or copied into another virus (vaccinia virus - MVA), to synthesise the BTV proteins in vaccinated animals and thus ativating their immune system. By incorporating the synthesised and purified viral proteins, DNAs or MVA into microscopic synthetic beads that breakdown over time in a controlled way. This should prolong the exposure of the animals to the vaccine, allowing more time to generate a higher level of protection against the virus, and therefore better protection against the disease. These new vaccination strategies are considered to be entirely safe, since they do not use live BTV to induce immunity/protection. They will therefore be used in different combinations to see which is most effective, and to design a better (and safer) vaccine. Because of the promise shown by these new types of vaccines, we will use this opportunity to study in more detail how they work. We want to find out if the position of the proteins on or in the beads affects the way the immune system responds to them. At the same time, we want to study which gives the best response : the use of each component on a single bead system, or beads containg different proteins and/or DNAs. Our ultimate goal being a vaccine that is 100% efficient after a single dose.