Characterise the virological and immunological events in sheep during infection and vaccination with Jaagsiekte sheep retrovirus (JSRV). Evaluate several candidate vaccines. Provide proof of principle that a protective immune response to JSRV can be induced in sheep by vaccination.
Brief description: The project comprises six integrated packages: -
Development of techniques for the propagation and quantitation of JSRV: a recently developed infectious, pathogenic molecular clone of JSRV will be used to identify and optimise a permissive cell culture system for JSRV. Techniques to quantitate in vitro propagated JSRV in culture supernates and inocula will be optimised. A PCR protocol to detect JSRV viraemia will be optimised.
Assays to measure ovine immune responses to JSRV: JSRV CA and SU sequences will be expressed in appropriate vectors to yield soluble products. The recombinant proteins will be purified and used to develop and optimise ELISAs for antibodies and assays for CMI responses to JSRV.
Optimise challenge system to induce SPA in older lambs: in vitro propagated JSRV virions will be used to inoculate lambs. The effect of age at inoculation and virus dose to influence the incubation period and number of infected/affected lambs will be determined. The results will be used to set the best combination of dose and age that can be used for evaluation of candidate vaccines.
Obtain infectious molecular clone of caprine enzootic nasal tumour virus (ENTV): a full-length provirus clone(s) of caprine ENTV will be obtained from a genomic library made from tumour DNA. Using knowledge and expertise gained in objective 1, the clones will be characterised to select an infectious molecular clone that will be employed to identify and optimise a permissive cell culture system for caENTV.
Immunological comparison of potential JSRV vaccines: the qualitative and quantitative humoral and CMI responses of at least seven vaccine candidates will be compared, using the new techniques developed in objective 2. The approaches that stimulate the most appropriate immune responses will be selected for further assessment.
Proof of principle that protection is provided by vaccination: lambs will be immunised with the vaccine selected from the preceding studies. They will be challenged intratracheally with JSRV according to the protocol derived from objective 3. The level of protection will be assessed by monitoring for subsequent infection, as indicated by viraemia, and development of clinical signs or lesions at necropsy.
Funding SchemeCSC - Cost-sharing contracts
EH1 1HN Edinburgh