Assessment of efficacy of a bivalent BTV-2 and BTV-4 inactivated vaccine by vaccination and challenge in cattle

Abstract

19The efficacy of a bivalent inactivated vaccine against bluetongue virus (BTV) serotypes 2 (BTV-20 2) and 4 (BTV-4) was evaluated in cattle by general and local examination, serological follow-21 up, and challenge. 22Thirty-two 4 month-old calves were randomly allocated into 2 groups of 16 animals each. One

Opinion of the Scientific Panel on Animal Health and Welfare (AHAW) on request from the Commission on bluetongue vectors and vaccines

“…Similarly, studies with recent European isolates of BTV serotypes 2, 4, 9 and 16 established viraemia periods of 14 to 45 days in experimentally infected sheep (longest in sheep inoculated with serotype 2), up to 31 days in goats inoculated with serotype 2, and up to 19 days in cattle inoculated with serotype 2 or 4 Savini et al, 2001Savini et al, , 2006aSavini et al, , 2006b. Viraemia persisted in sheep vaccinated with live attenuated strains of BTV-2, -4, -9 and -16 (including multivalent constructs) for up to 24 days whereas viraemia in cattle inoculated with the same live-attenuated vaccine viruses persisted for up to 78 days 2006;Savini et al, 2004b;2005b;.…”

Current and next-generation bluetongue vaccines: Requirements, strategies, and prospects for different field situations

“…The first commercially available inactivated BT vaccine was against serotype 2. Later, inactivated vaccines against serotype 4 and the bivalent vaccine against serotypes 2 and 4 have been used in southern Europe (Savini et al, 2009). Heterologous protection by inactivated BT vaccines can be induced, but cross protection is difficult to predict.…”

Bluetongue vaccines in Europe

“…The use of inactivated vaccines avoid risk associated with the use of live-attenuated vaccines, such as reversion to virulence, reassortment of genes with field strain, teratogenicity and insufficient attenuation leading to clinical disease ). Although the hitherto available inactivated vaccines need to be administered twice (particularly in cattle), are rather expensive to produce and are primarily directed against only one serotype, they proved to be safe and effective (Schwartz-Cornil et al 2008, Savini et al 2009, Gethmann et al 2009). Therefore, the European Food Safety Authority currently recommends using inactivated vaccines to protect animals from bluetongue disease (Enserink 2008), instead of MLV vaccines.…”

“…related to vaccination. Some vaccines induced transient local reactions of variable severity with different frequency (Savini et al 2009). Assessment of efficacy is based on clinical and virological data as well as on immunogenicity.…”

“…At the time of the challenge, only one of 16 vaccinated animals did not have neutralizing antibodies against BTV4, while the remaining 15 animals showed titres of at least 1:10 for either BTV serotypes 2 or 4. However, the BTV2 component of the bivalent BT vaccine elicited a stronger immune response in terms of both the number of virus neutralization (VN)-positive animals and antibody titres (Savini et al 2009). The long-term efficacy of three commercially available inactivated vaccines against bluetongue virus serotype 8 (BLUEVAC 8, Zulvac 8 and BTVPUR AlSap 8) was evaluated in a seroprevalence study and challenge experiments by Wackerlin et al (2010).…”