Current perspectives on conventional and novel vaccines against peste des petits ruminants

Peste des petits ruminants (PPR) is an acute or subacute, highly contagious viral disease of small ruminants, characterized by fever, oculonasal discharges, stomatitis, diarrhoea and pneumonia. This disease is included in the OIE (Office International des Epizooties) list of notifiable terrestrial animal diseases. PPR was first described in the early 1940s in Côte d'Ivoire, and at present, PPR is mainly circulating in Western and Central Africa, the Arabian Peninsula and Southern Asia. Peste des petits ruminants virus (PPRV), the etiological agent of PPR, is classified into the genus Morbillivirus in the family Paramyxoviridae, as its biological and physicochemical features are closely related to the other morbilliviruses. The first homologous PPR vaccine was developed by an artificially attenuated PPRV, named as Nigeria 75/1, which has been widely used in the production of live attenuated vaccines to protect small ruminants. A new generation of PPR vaccine candidates can be genetically modified to differentiate infected from vaccinated animals (DIVA), which nevertheless is difficult to achieve by conventional vaccines. In this review, we systematically discussed a broad range of vaccines against PPR, including commercially available vaccines and potential vaccine candidates, and further DIVA strategies for immunization with the new generation vaccines.