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                     PALE-Blu project brochure1Understanding pathogen, livestock, environment interactions involving bluetongue virus: the PALE-Blu ILRI PROJECT BROCHUREThe International Livestock Research Institute (ILRI) recently received funding from the European Union (Horizon 2020), in partnership with scientists from 19 different research institutes and universities around the world, to investigate the prevalence and the diversity of circulating BTV serotypes in key regions of sub-Saharan Africa. ILRI’s part of the study is to collect samples from different animal species present in different countries of Africa where BTV data is lacking. Emphasis will also be placed on an in-depth understanding of the prevalence of the virus in different agroecological zones in Kenya. Analysis of the samples will include ELISA to measure anti-BTV antibodies indicating prior exposure to the virus, quantitative PCR (qPCR) to assess the level of ongoing infection, and molecular typing by qPCR to identify the most prevalent circulating serotypes in these regions. BTV isolation on insect cells will also be attempted from positive field samples to eventually generate a biobank of BTV field isolates from the sub-continent. These virus strains can then be used for further characterization by next-generation sequencing, or for pathogenesis, transmission and vaccination studies at ILRI and with international partners.  The data generated from this study will shed more light on the status of BTV in sub-Saharan African and will hopefully lead to strategies for a better control of the disease in the future. Key messages Bluetongue virus (BTV) is widespread in sub-Saharan Africa and causes a disease that mainly affects sheep. Bluetongue (BT) can cause substantial economic losses due to fatalities of livestock, or due to ban on the livestock trade between countries.  A better understanding of the circulating serotypes in Africa, spread dynamics of the virus, and the development of a multivalent vaccine towards BTV will allow for a better control and prevention of future outbreaks. ILRI recently received funding to investigate on the current circulating BTV serotypes in sub-Saharan Africa  The disease Bluetongue (BT) is a vector borne disease caused by the bluetongue virus (BTV) that affects livestock such as sheep, goat or cattle. It can also infect wild animals such as antelopes, deer and wildebeest, to name a few. The disease is most severe in sheep and can result in death. The causative agent of this disease is an Orbivirus member of the Reoviridae family, a virus family in which the human pathogens reovirus and rotavirus are also found. Cattle are the principal reservoir of BTV but usually do not develop clinical signs of the disease.  The clinical signs of the disease manifests within 5–10 days post infection and include fever; swelling of the face, lips and tongue; breathing difficulties; and sores on the muzzle and gums. Reddening will also be observed on the mucosal membranes of the eyes, nose and mouth. The severity of the disease varies depending on the viral strains, the animal species and the environment. To date, there are 27 serotypes of BTV that have been identified and new types are still being discovered. This virus is transmitted by Culicoides biting midges and is thus rightly called an arbovirus. However, some serotypes are transmitted without the help of the arthropod vector.  The impact In sub-Saharan African BTV has been shown to be present in Ethiopia, Sudan, Kenya, Uganda, Tanzania, Botswana, Mozambique, Zimbabwe and South Africa. However, information is still lacking on BTV prevalence in other neighboring countries of eastern, central, and southern Africa. Past and recent studies have indicated the high level of antibodies to BTV in sentinel cattle in Western Kenya, reaching nearly 90% of cattle sampled being positive, indicating high exposure to the virus. Moreover, PCR positive cattle indicated that nearly 50% of them had an ongoing sub-clinical infection. IContact Nicholas Svitek n.svitek@cgiar.org Nairobi, Kenya  Lucilla Steinaa l.steinaa@cgiar.org Nairobi, Kenya Ilri.org  https://www.paleblu.eu/ This publication is copyrighted by the International Livestock Research Institute (ILRI). It is licensed for use under the Creative Commons Attribution 4.0 International Licence.                  January 2020ILRI thanks all donors that globally support its work through their contributions to the CGIAR Trust FundPatron: Professor Peter C Doherty AC, FAA, FRS Animal scientist, Nobel Prize Laureate for Physiology or Medicine–1996Box 30709, Nairobi 00100 Kenya Phone  +254 20 422 3000 Fax      +254 20 422 3001 Email ilri-kenya@cgiar.orgilri.org better lives through livestock  ILRI is a CGIAR research centreBox 5689, Addis Ababa, Ethiopia Phone +251 11 617 2000 Fax +251 11 667 6923 Email ilri-ethiopia@cgiar.org ILRI has offices in East Africa • South Asia • Southeast and East Asia • Southern Africa • West AfricaFortunately, BTV does not infect humans and therefore does not pose a threat to food safety. But it does pose a threat to food security since sheep are one of the largest livestock population in sub-Saharan Africa, arriving only second to cattle, according to the Food and Agriculture Organization of the United Nations (FAO). Understanding the dynamics behind what drives BTV spread can prevent new outbreaks. Several factors such as changes in climate can influence the spread of the virus. For example, rain and wind directions can significantly influence midges’ distribution over large territories. The high prevalence and diversity of the BTV serotypes circulating in sub-Saharan Africa poses a high risk of introducing BTV to neighboring regions where BTV is controlled or absent, including Europe. A recent BT outbreak in Europe is believed to have originated from a serotype only detected in sub-Saharan Africa.  The only effective way to control the disease is through vaccination. Several vaccines are available for BTV, however, they are serotype specific. This poses a challenge as the vaccine will only protect against one serotype and will not provide immunity to the other circulating serotypes. Current research at partner institutions include developing multivalent vaccines that will protect against several serotypes at the same time.References Adam, I.A., Abdalla, M.A., Mohamed, M.E. and Aradaib, I.E. 2014. Prevalence of bluetongue virus infection and associated risk factors among cattle in North Kordufan State, Western Sudan. BMC veterinary research 10. 94. 10.1186/1746-6148-10-94. Belbis, G., Zientara, S., Bréard, E., Sailleau, C., Caignard, G. et al. 2017. Bluetongue Virus: From BTV-1 to BTV-27. Advances in Virus Research 99:161–197. Bessell, P.R., Searle, K.R., Auty, H.K., Handel, I.G., Purse, B.V. and Bronsvoort, B.M. 2016. Assessing the potential for Bluetongue virus 8 to spread and vaccination strategies in Scotland. Scientific Reports 6. 38940. 10.1038/srep38940. Courtejoie, N., Cauchemez, S., Zanella, G. and Durand, B. 2019. A network-based approach to modelling bluetongue spread in France. Preventive Veterinary Medicine 170:104744. Courtejoie, N., Durand, B., Bournez, L., Gorlier, A., Bréard, E. et al. 2018. Circulation of bluetongue virus 8 in French cattle, before and after the re-emergence in 2015. Transboundary and Emerging Diseases 65(1): 281–284. Elhassan, A.M., Fadol, M.A. and El Hussein, A.R. 2014. Seroprevalence of bluetongue virus in dairy herds with reproductive problems in Sudan. ISRN Veterinary Science. 2014. 595724. 10.1155/2014/595724. Federici, V., Goffredo, M., Mancini, G., Quaglia, M., Santilli, A. et al. 2019. Vector Competence of Italian Populations of Culicoides for Some Bluetongue Virus Strains Responsible for Recent Northern African and European Outbreaks. Viruses 11. 10.3390/v11100941. Khair, H.O., Adam, I.A., Bushara, S.B., Eltom, K.H., Musa, N.O. and Aradaib, I.E. 2014. Prevalence of bluetongue virus antibodies and associated risk factors among cattle in East Darfur State, Western Sudan. Irish Veterinary Journal 67(1):4. Mintiens, K., Méroc, E., Mellor, P.S., Staubach, C., Gerbier, G. et al. 2008. Possible routes of introduction of bluetongue virus serotype 8 into the epicentre of the 2006 epidemic in north-western Europe. Preventive Veterinary Medicine 87(1–2): 131–44. Toye, P.G., Batten, C.A., Kiara, H., Henstock, M.R., Edwards, L. et al. 2013. Bluetongue and epizootic haemorrhagic disease virus in local breeds of cattle in Kenya. Research in Veterinary Sciences 94(3):769–73.Photo credit: ILRI/Stevie Mann

Understanding pathogen, livestock, environment interactions involving bluetongue virus: The PALE-Blu project

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Understanding pathogen, livestock, environment interactions involving bluetongue virus: The PALE-Blu project

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