Publications

Marek's disease virus (MDV) is a lymphotropic alphaherpesvirus that induces fatal rapid-onset T-cell lymphomas in chickens, its natural host. The MDV-encoded nuclear oncoprotein Meq is essential for lymphomagenesis and acts as a regulator of transcription. Meq has structural features, including a basic domain adjacent to a leucine zipper motif (B-ZIP), that suggest it is related to the Jun/Fos family of transcription factors. Via the leucine zipper, Meq can form homodimers or heterodimerize with c-Jun. Meq/Meq homodimers are associated with transrepression, and Meq/Jun heterodimers can transactivate target genes carrying an AP-1-like binding site. In order to determine the role of the leucine zipper and of Meq dimerization in T lymphomagenesis, specific point mutations were engineered into the highly oncogenic RB-1B strain of MDV to produce virus completely lacking a functional Meq leucine zipper (RB-1B MeqBZIP/BZIP) or virus encoding Meq that cannot homodimerize but can still bind to c-Jun and an AP-1-like site on DNA (RB-1B MeqHom/Hom). Both of these mutant viruses were capable of replication in cultured chicken embryo fibroblasts. However both mutations resulted in a complete loss of oncogenicity, since no lymphomas were produced up to 90 days postinfection in experimentally infected chicks. We conclude that the leucine zipper is necessary for the oncogenic activity of Meq and/or the efficient establishment of long-term MDV latency in T cells. Moreover, it appears that the ability to form homodimers is an absolute requirement and the ability to bind c-Jun alone is insufficient for the T-cell lymphomagenesis associated with virulent MDV.

Bluetongue virus (BTV) is an arbovirus (arthropod-borne virus) that is spread between its ruminant hosts by vector species of Culicoides biting midges (Diptera: Ceratopogonidae). Culicoides are among the smallest of haematophagous flies, with a wingspan that rarely exceeds 4mm, making them extremely challenging subjects for experimental research. In susceptible ruminants (primarily fine wool breeds of sheep), infection with BTV can cause a haemorrhagic disease (bluetongue: BT). Since 2006, the international profile of the virus has risen substantially as a result of a widespread and economically damaging incursion of a sub-Saharan strain of BTV serotype 8 (BTV-8) into north-western Europe, a region where the virus had never previously been recorded. This step-change in the epidemiology of the virus is thought to be a consequence both of globalisation of trade (although a specific pathway of introduction for BTV-8 has not been definitively identified), and the influence of climate within those affected regions in driving virus transmission. The effect of the BTV-8 incursion was initially most obvious in sheep holdings where mortality due to BT was observed. In addition, however, many cattle in northern Europe were also significantly affected with widespread cases of infertility, abortion and reduced milk yield, impacting directly upon the efficient operation of beef and dairy holdings. The full impact of these clinical cases and the animal movement restrictions imposed to reduce spread of the virus is poorly characterised, but from small scale studies is likely to amount to 100s of millions of Euros. From as early as the late 1970s, the UK was unique among north-western European countries in funding a sustained and continuous research programme on BTV and on Culicoides as vectors of animal pathogens. Following the appearance of BTV-8 in northern Europe in 2006, many of the findings that had been achieved as part of this programme were used to devise responses to the incursion, at both an EU and UK level. In this paper, the UK's response to the incursion and which areas of entomological research proved useful in predicting, monitoring and mitigating against BTV outbreaks are considered.

We have analyzed the potential of virus-like particles (VLPs) from rabbit hemorrhagic disease virus (RHDV) as a delivery system for foreign T cell epitopes. To accomplish this goal, we generated chimeric RHDV-VLPs incorporating a CD8(+) T cell epitope (SIINFEKL) derived from chicken ovalbumin (OVA). The OVA epitope was inserted in the capsid protein (VP60) of RHDV at two different locations: 1) the N-terminus, predicted to be facing to the inner core of the VLPs, and 2) a novel insertion site predicted to be located within an exposed loop. Both constructions correctly assembled into VLPs. In vitro, the chimeric VLPs activated dendritic cells for TNF-alpha secretion and they were processed and presented to specific T cells. In vivo, mice immunized with the chimeric VLPs without adjuvant were able to induce specific cellular responses mediated by cytotoxic and memory T cells. More importantly, immunization with chimeric VLPs was able to resolve an infection by a recombinant vaccinia virus expressing OVA protein.