Humoral Immunogenicity and Efficacy of a Single Dose of ChAdOx1 MERS Vaccine Candidate in Dromedary Camels.
Alharbi NK., Qasim I., Almasoud A., Aljami HA., Alenazi MW., Alhafufi A., Aldibasi OS., Hashem AM., Kasem S., Albrahim R., Aldubaib M., Almansour A., Temperton NJ., Kupke A., Becker S., Abu-Obaidah A., Alkarar A., Yoon I-K., Azhar E., Lambe T., Bayoumi F., Aldowerij A., Ibrahim OH., Gilbert SC., Balkhy HH.
MERS-CoV seronegative and seropositive camels received a single intramuscular dose of ChAdOx1 MERS, a replication-deficient adenoviral vectored vaccine expressing MERS-CoV spike protein, with further groups receiving control vaccinations. Infectious camels with active naturally acquired MERS-CoV infection, were co-housed with the vaccinated camels at a ratio of 1:2 (infected:vaccinated); nasal discharge and virus titres were monitored for 14 days. Overall, the vaccination reduced virus shedding and nasal discharge (p = 0.0059 and p = 0.0274, respectively). Antibody responses in seropositive camels were enhancedby the vaccine; these camels had a higher average age than seronegative. Older seronegative camels responded more strongly to vaccination than younger animals; and neutralising antibodies were detected in nasal swabs. Further work is required to optimise vaccine regimens for younger seronegative camels.