Capripoxvirus-vectored vaccines against livestock diseases in Africa

Five different viral diseases of livestock, lumpy skin disease (LSD), sheep pox (SPP), goat pox (GTP), Rift Valley fever (RVF) and peste des petits ruminants (PPR), circulate in the same regions of Africa, imposing a major burden on economic activity and public health. While commercial vaccines against these viruses are available, the cost of implementing regular vaccination regimens against multiple diseases is prohibitive for most African farmers. A single, affordable multivalent vaccine that simultaneously protects against all 5 diseases would therefore be of significant benefit to the livestock sector in Africa. It could also serve as a platform for the development of new vaccines of significance to other developing countries around the world. In this paper, we present an overview of the economic importance of livestock in Africa, the pathogens responsible for RVF, PPR, SPP, GTP and LSD and the vaccination strategies currently used to combat them. We then review experience with the development of attenuated capripoxviruses as vaccines against LSD, SPP and GTP and of recombinant capripoxvirus-vectored vaccines against RVF and PPR. We conclude the article by presenting the rationale for a single, multivalent capripoxvirus-vectored vaccine that would protect against all 5 diseases of livestock, and describe the approach being taken by a consortium of Canadian and South African researchers to develop such a vaccine.