SummaryAn ideal vaccine against mucosal pathogens such as Middle East respiratory syndrome coronavirus (MERS-CoV) should confer sustained, protective immunity at both systemic and mucosal levels. Here, we evaluated the in vivo systemic and mucosal antigen-specific immune responses induced by a single intramuscular or intragastric administration of recombinant adenoviral type 5 (Ad5) or type 41 (Ad41) -based vaccines expressing the MERS-CoV spike (S) protein. Intragastric administration of either Ad5-S or Ad41-S induced antigen-specific IgG and neutralizing antibody in serum; however, antigen-specific T-cell responses were not detected. In contrast, after a single intramuscular dose of Ad5-S or Ad41-S, functional antigen-specific T-cell responses were elicited in the spleen and pulmonary lymphocytes of the mice, which persisted for several months. Both rAdbased vaccines administered intramuscularly induced systemic humoral immune responses (neutralizing IgG antibodies). Our results show that a single dose of Ad5-S-or Ad41-S-based vaccines represents an appealing strategy for the control of MERS-CoV infection and transmission.

Severe acute respiratory syndrome (SARS) is an acute respiratory infectious disease that spread worldwide in early 2003. The cause was determined as a novel coronavirus (CoV), SARS-associated CoV (SARS-CoV), with a single-stranded, plus-sense RNA. To date, no effective specific treatment has been identified. To exploit the possibility of using RNA interference as a therapeutic approach to fight the disease, plasmid-mediated small interfering RNAs (siRNAs) were generated to target the SARS-CoV genome. The expression of siRNAs from two plasmids, which specifically target the viral RNA polymerase, effectively blocked the cytopathic effects of SARS-CoV on Vero cells. These two plasmids also inhibited viral replication as shown by titer assays and by an examination of viral RNA and protein levels. Thus, our results demonstrated the feasibility of developing siRNAs as effective anti-SARS drugs.

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