Lumpy skin disease virus (LSDV) is the causative agent of lumpy skin disease (LSD), an endemic disease of cattle in Africa and the Middle East where it produces significant economic loss and acts as a barrier to trade. Since 2012 LSDV has spread into Turkey, Europe, the Caucasus and Russia . The epidemic has resulted in the slaughter of thousands of cattle, mass vaccination campaigns, animal movement restrictions and export bans. One of the key knowledge gaps hampering control efforts is an understanding of how LSD is transmitted from animal to animal and herd to herd. LSD expert panels and numerous LSD-themed workshops in recent years have all identified research into vector-borne transmission of LSD as a high priority. This will be addressed in this research project. The project hypothesis is: Viable LSDV persists in insect vectors at suitable sites and for sufficient time to allow onward transmission to cattle hundreds of kilometres distant. This proposed work involves two objectives running in parallel over 18 months. Objective 1 To identify the most likely vector group responsible for transmission of LSDV. This objective will undertake experimental transmission of LSDV from infected cattle by potential insect vectors in the high containment facilities at The Pirbright Institute. These studies will use contemporary virus detection techniques to distinguish between mechanical and biological transmission, and estimate the risk of different insect vectors that are present in Europe. The vector potential of four insect species, Stomoxysis calcitrans (stable flies), Culicoides nubeculosus midge, and Aedes aegypti and Culex quinquefasciatus mosquitoes, will be investigated. The four species were each selected on the basis of their distribution in affected and / or threatened areas, evidence from the literature of their experimental or epidemiological link to LSDV transmission, and because they represent different feeding mechanisms (solenophagous vs telmophagous). Objective 2 To assess the risk posed by LSDV and the potential impact of different control measures. This objective will integrate the experimental results into models of LSDV and, hence, explore the risk of disease and impact of different control measures. Overall the project will provide scientific evidence on vector-borne transmission of LSDV to enable effective and proportional LSD control programmes to be designed and the current Eurasian LSD epidemic to be contained. The project utilises the unique and world-class expertise at Pirbright in lumpy skin disease research, multi-scale modelling of viral diseases of livestock, the biology of blood-feeding insects, in vivo transmission studies of viruses between natural ruminant hosts and vectors, and cutting-edge bioimaging of arthropods to study vector-borne transmission of LSDV. The project is sponsored by an industrial partner MSD Animal Health, producer of the widely used Lumpyvax vaccine against LSD. MSD Animal Health are partnering Pirbright in this project to enable LSD vaccination campaigns to be augmented with scientifically rational control programmes aimed at reducing vector-borne transmission of LSDV. This approach is in accordance with Merck Animal Health's philosophy that their responsibilities extend beyond their primary business goals. By supporting this research project they aim to add value to efforts to control and eradicate LSD and thereby provide benefit to the environment and wider society as a whole. The project is also supported by DEFRA, the UK government department responsible for protecting the UK from exotic diseases such as lumpy skin disease (LSD). This support emphasises the impact this research will have on reducing the risk of LSD incursion into the UK, and facilitating its rapid eradication if it does occur.