RF captured all CLSM images and prepared them for publication. DX, BM, RP and JGC conceived, co-ordinated, designed and procured the funding for the study. All authors have read and approved the final article. This work was supported by the Medical

Research Council (grant no. G0801955). The authors would like to thank Dr. Katrina Davidson, Dr. Clair Lyle and Dr. Johann Partridge of XstalBio Ltd. for their invaluable technical advice and support throughout this study. We would also like to thank Dr. Fatme Mawas and David Eastwood (NIBSC) for advice on flow cytometry and Mrs. Margaret Mullin (University of Glasgow) for her support with SEM. Conflicts of interest: BM is a shareholder in XstalBio Ltd. which is a private company commercially developing CaP-PCMCs. “
“Bluetongue virus is the type species of 17-AAG datasheet genus Orbivirus, family Reoviridae [1] and [2]. Bluetongue viruses (BTV) are transmitted by adult Culicoides midges, causing ‘bluetongue’ (BT), a non-contagious but economically important disease of ruminants (sheep, cattle and some species of deer) [3] and [4]. Currently 26 BTV serotypes have been identified, 10 of which (BTV-1, 2, 4, 6, 8,

9, 11, 14, 16 and 25) have been detected in Europe since 1998 [5], [6] and [7]. It is estimated that over one million sheep have died during repeated BT incursions into the Mediterranean AZD2281 basin between 1998 and 2005 [5]. An outbreak caused by BTV-8 that started in the Netherlands during 2006, subsequently spread across most of Europe, causing high levels of of mortality in sheep (15–32%, reaching ∼50% is some areas), as well as significant clinical signs but low mortality (<1%) in cattle [8], [9], [10], [11], [12] and [13]. However, inactivated-virus vaccines were used successfully, leading to the rapid eradication of BTV-8 from the region.

These inactivated vaccines, which were made available for serotypes 1, 2, 4 and 8 of BTV are thought to work primarily through generation of a protective serotype-specific neutralising-antibody response targeting the VP2 antigen [2], [14], [15], [16], [17], [18], [19], [20] and [21]. The BTV particle is made of seven structural proteins (VP1–VP7) [2], [22] and [23]. VP2 represents a primary target for neutralising antibodies [1], [2], [16] and [17] and determines virus serotype [24]. VP2 shows 22.4–73% aa sequence variation between BTV serotypes [24]. VP5 of BTV, the second most variable BTV protein (aa identity of 41–79% between BTV serotypes [25] and [26]) enhances neutralising antibody response to VP2 [1], [2], [14] and [27]. Selected structural-proteins of BTV-4, including two domains of VP2 (aa 63–471 and 555–956), VP5 (from which a coiled-coil sequence [amino acids 1–100] was deleted to improve solubility) and full-length VP7, were expressed in bacteria as soluble fusion-proteins with glutathione S-transferase (GST).