Recombinant Receptor Binding Domain Protein Induces Partial Protective Immunity in Rhesus Macaques Against Middle East Respiratory Syndrome Coronavirus Challenge()

Lan, Jiaming; Yao, Yanfeng; Deng, Yao; Chen, Hong; Lu, Guangwen; Wang, Wen; Bao, Linlin; Deng, Wei; Wei, Qiang; Gao, George F.; Qin, Chuan; Tan, Wenjie

Nine monkeys were randomly assigned to high-dose (H), low-dose (L), and mock (M) groups (Table 1) . High-dose animals were primed with 200 μg rRBD and boosted with 100-μg rRBD admixed with 1 mg of alum adjuvant. The three low-dose animals were primed with 50 μg rRBD and boosted with 25 μg rRBD admixed with 1 mg of alum adjuvant; control animals were immunised with PBS with 1 mg of alum adjuvant. Animals received their second immunisation 8 weeks subsequent to their first. To assess long-term immunological responses, the interval between the second and third immunisations was 17 weeks. Each vaccine formulation was administered intramuscularly (i.m.). Two weeks after each immunisation, animals were bled periodically to obtain serum and peripheral blood mononuclear cells (PBMCs) for immunological analysis.