Immunogenicity of Candidate MERS-CoV DNA Vaccines Based on the Spike Protein.
MERS-coronavirus is a novel zoonotic pathogen which spread rapidly to >25 countries since 2012. Its apparent endemicity and the wide spread of its reservoir host (dromedary camels) in the Arabian Peninsula highlight the ongoing public health threat of this virus. Therefore, development of effective prophylactic vaccine needs to be urgently explored given that there are no approved prophylactics or therapeutics for humans or animals to date. Different vaccine candidates have been investigated but serious safety concerns remain over protein or full-length spike (S) protein-based vaccines. Here, we investigated the immunogenicity of naked DNA vaccines expressing different fragments of MERS-CoV S protein in mice. We found that plasmids expressing full-length (pS) or S1-subunit (pS1) could induce significant levels of S1-specific antibodies (Abs) but with distinct IgG isotype patterns. Specifically, pS1 immunization elicited a balanced Th1/Th2 response and generally higher levels of all IgG isotypes compared to pS vaccination. Interestingly, only mice immunized with pS1 demonstrated significant S1-specific cellular immune response. Importantly, both constructs induced cross-neutralizing Abs against multiple strains of human and camel origins. These results indicate that vaccines expressing S1-subunit of the MERS-CoV S protein could represent a potential vaccine candidate without the possible safety concerns associated with full-length protein-based vaccines.
Special Infectious Agents Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia.
Sawsan S
SS
Al-Amri
Special Infectious Agents Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia.|Biotechnology Research Laboratories, Gastroenterology Surgery Center, Mansoura University, Mansoura, Egypt.
Ayman T
AT
Abbas
Special Infectious Agents Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia.
Loai A
LA
Siddiq
Special Infectious Agents Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia.
Abrar
A
Alghamdi
Hematology Laboratory, King Abdulaziz University Hospital, Jeddah, Saudi Arabia.
Mohammad A
MA
Sanki
Materials Science Research Institute, National Nanotechnology Center, King Abdulaziz City for Science and Technology (KACST), Riyadh, Saudi Arabia.
Muhanna K
MK
Al-Muhanna
Special Infectious Agents Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia.|Department of Medical Laboratory Technology, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia.
Rowa Y
RY
Alhabbab
Special Infectious Agents Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia.|Department of Medical Laboratory Technology, Faculty of Applied Medical Sciences, King Abdulaziz University, Jeddah, Saudi Arabia.
Esam I
EI
Azhar
Center for Vaccine Evaluation; Biologics and Genetic Therapies Directorate; Health Canada; Ottawa, Ontario, Canada.
Xuguang
X
Li
Special Infectious Agents Unit, King Fahd Medical Research Center, King Abdulaziz University, Jeddah, Saudi Arabia.|Department of Medical Microbiology and Parasitology, Faculty of Medicine, King Abdulaziz University, Jeddah, Saudi Arabia.
Anwar M
AM
Hashem
D000818:Animals; D057134:Antibodies, Neutralizing / Q000276:immunology; D000914:Antibodies, Viral / Q000276:immunology; D002162:Camelus; D002522:Chlorocebus aethiops; D018352:Coronavirus Infections / Q000276:immunology* / Q000517:prevention & control*; D004195:Disease Models, Animal; D005260:Female; D006801:Humans; D007114:Immunization; D000071497:Immunogenicity, Vaccine; D007074:Immunoglobulin G / Q000276:immunology; D051379:Mice; D065207:Middle East Respiratory Syndrome Coronavirus / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D009500:Neutralization Tests; D064370:Spike Glycoprotein, Coronavirus / Q000235:genetics / Q000276:immunology*; D019444:Vaccines, DNA / Q000235:genetics / Q000276:immunology*; D014709:Vero Cells; D014765:Viral Vaccines / Q000235:genetics / Q000276:immunology*
D057134:Antibodies, Neutralizing; D000914:Antibodies, Viral; D007074:Immunoglobulin G; D064370:Spike Glycoprotein, Coronavirus; D019444:Vaccines, DNA; D014765:Viral Vaccines