A comparison of different vaccination schemes used in sheep combining inactivated bluetongue vaccines against serotypes 4 and 8.

Eight different vaccination schemes using four commercially available inactivated Bluetongue vaccines against serotypes 4 and 8 in three different combinations (setting 1-3) were tested under field conditions for their ability to generate a measurable immune response in sheep. Animals of setting 1 (groups A-D) were simultaneously vaccinated using either individual injections at different locations (groups A & D) or double injection by a twin-syringe (groups B & C). For both application methods, a one-shot vaccination (groups C & D) was compared to a boosted vaccination (groups A & B). Sheep of setting 2 (groups E-G) were vaccinated in an alternating, boosted pattern at fortnightly intervals starting with serotype 4 (groups E & F) or vice versa (group G). Group H of setting 3 was vaccinated simultaneously and vaccines were injected individually as a one-shot application. Each group consisted of 30 sheep. The immunogenic response was tested in all sheep (n = 240) by ELISA (IDScreen®Bluetongue Competition), while serum neutralisation tests were performed in five to six sheep from each group (n = 45). All vaccine combinations were well tolerated by all sheep. Of all vaccines and schemes described, the simultaneous double injected boosted vaccination of setting 1 (group B) yielded the highest median serotype-specific titres 26 weeks after the first vaccination (afv) and 100% seropositive animals (ELISA) one year afv. In setting 1, there were no relevant significant differences in the immunogenic response between simultaneously applied vaccines at different sites or at the same injection site. Importantly, a one-shot vaccination induced comparable immunogenicity to a boosted injection half a year afv. Low serotype-specific neutralising antibody levels were detected in settings 2 and 3 and are attributed to diverse factors which may have influenced the measured immunogenicity.

Measles virus M protein-driven particle production does not involve the endosomal sorting complex required for transport (ESCRT) system.

Assembly and budding of enveloped RNA viruses rely on viral matrix (M) proteins and host proteins involved in sorting and vesiculation of cellular cargoes, such as the endosomal sorting complex required for transport (ESCRT). The measles virus (MV) M protein promotes virus-like particle (VLP) production, and we now show that it shares association with detergent-resistant or tetraspanin-enriched membrane microdomains with ebolavirus VP40 protein, yet accumulates less efficiently at the plasma membrane. Unlike VP40, which recruits ESCRT components via its N-terminal late (L) domain and exploits them for particle production, the M protein does this independently of this pathway, as (i) ablation of motifs bearing similarity to canonical L domains did not affect VLP production, (ii) it did not redistribute Tsg101, AIP-1 or Vps4A to the plasma membrane, and (iii) neither VLP nor infectious virus production was sensitive to inhibition by dominant-negative Vps4A. Importantly, transfer of the VP40 L domain into the MV M protein did not cause recruitment of ESCRT proteins or confer sensitivity of VLP release to Vps4A, indicating that MV particle production occurs independently of and cannot be routed into an ESCRT-dependent pathway.