Background:
Peste-des-petits-ruminants (PPR) is a fatal viral disease of sheep and goats causing a global economic loss of about USD 2.1 billion/year. In line with Rinderpest eradication, FAO and WOAH have set a target for global eradication of PPR by 2030. Live attenuated PPRV/Nigeria/75/1 and PPRV/Sungri/96 are the two vaccines globally used for PPR control. Immune response elicited by these live vaccines is indistinguishable from active infection in the conventional diagnostic tests, thereby, making sero-monitoring intractable in endemic areas. Hence, it is imperative that the vaccine used must differentiate infected animals from vaccinated (DIVA) to claim global freedom from PPR:
PPR DIVA approaches concentrated mainly on recombinant protein-based subunit vaccines, virus like particles and vectored vaccines. While these vaccines were successful as DIVA candidates, they failed to offer the solid immunity conferred by the currently employed homologous vaccines. To achieve disease-free status without stopping vaccination in the monitoring period, we need to have effective homologous marker vaccines and DIVA assays, which can differentiate infected from vaccinated animals:
Technology Details:
To solve this problem, we developed homologous PPR marker vaccine from PPRV/Sungri/96 vaccine virus by employing cutting-edge reverse genetics techniques. With the availability of the marker vaccine and companion DIVA assays developed by us, absence of PPR virus circulation within a border can still be proved to international agencies without the need to stop vaccination. Thus, PPR-free status and eventually global freedom from PPRV can be achieved safe and quick. This is a direct and notable benefit of this invention. Our marker vaccine retains the same production scalability and all the safety and efficacy profiles of the parent Sungri/96 vaccine. In addition, the vaccine also confers the much-needed serological DIVA through the newly developed differentiation assays which will be a boon for the ongoing PPR eradication program. Following a single dose of marker vaccine we have demonstrated PPR antibodies for about 2.5 years now and the vaccine is projected to confer lifelong immunity to vaccinated animals.