Characterisation of porcine cytomegalovirus and development as a vaccine vector for classical swine fever virus
MetadataShow full item record
Classical swine fever (CSF) is a highly infectious viral disease found in domestic pigs and wild boar populations. Outbreaks have a large economic cost for the swine industry and cause significant morbidity and mortality in pigs. Only one compatible vaccine that allows the differentiation between infected and vaccinated animals (DIVA), Suvaxyn® CSF Marker vaccine, is commercially available. However, due to e.g. trading issues caused by vaccination of animals this vaccine is not used prophylactically and is only used in emergency situations to prevent spread of CSFV to wider areas. An urgent need exists for development of a safe, effective, DIVA compatible vaccine. This study set out to address this need by taking the initial steps towards developing porcine cytomegalovirus (PCMV), as a vaccine platform. CMV-based vaccines have been shown to induce strong, durable immune responses against heterologous antigens, and also have the potential to be self-disseminating, which would facilitate vaccination of inaccessible animal populations such as wild boar. The aim of the present study was to further characterise the in vitro growth characteristics of a recent PCMV isolate. Our results show PCMV to have a slow growth, and low titre phenotype. As a further step towards cloning of PCMV as an infectious BAC, recombinant BAC shuttle vectors were constructed and then characterised. Initial experiments using these shuttle vectors combined with homologous recombination and CRISPR/Cas9 technology to insert the BAC cassette within the PCMV genome are also described. In summary, the cloning of the shuttle vectors was successful but the results around PCMV replication kinetics provide preliminary evidence that there are difficulties to overcome before PCMV can be developed as a vaccine vector platform.