SARS Vaccines
Creative Biolabs is a world leader in the field of viral vaccine development. By consistently delivering the highest standards of quality, professionalism, and integrity, we want to become the partner of a choice for your requirements. With our extensive experience and advanced platform, we are therefore confident in offering the best vaccine development services for diseases caused by SARS. We guarantee the finest results for our customers all over the world.
Severe acute respiratory syndrome (SARS) is a viral respiratory illness caused by a new human coronavirus which is called SARS-associated coronavirus (SARS-CoV), order Nidovirales, family Coronaviridae. The route of transmission occurred person to person, mostly via droplets containing infectious agents into the air and the incubation period of SARS ranges between 3 to 10 days. A high fever is the first significant symptom accompanied by cough, pneumonia, breathing difficulties, headache, chill and so on. It is believed to be an animal virus that crossed the species barrier to infect humans and caused a lot of people infections and deaths in 32 countries in 2002-2003, and also led to travel restrictions and significant effects on the global economy. Therefore, some vaccines to fight SARS are under development, in case the disease resurfaces.
Cellular Mechanisms of SARS
Spike (S) proteins of coronaviruses cause SARS associates with cellular receptors which is angiotensin-converting enzyme 2 (ACE2) to mediate infection of their target cells. ACE2 is a metallopeptidase that efficiently binds the S1 domain of the SARS-CoV S protein. Cytoplasmic vimentin was transformed to the cell surface and interacted with the spike-ACE2 complex, opening an entry for SARS-CoV. The rearrangement of vimentin from intracellular compartments to the cell surface might be resulted from the phosphorylation of vimentin through the activation of Ras-ERK signaling pathway induced by the interaction between SARS-CoV spike protein and ACE2. Finally, the vimentin further participates in the viral entry by combining with the spike-ACE2 complexes.
Fig. 2 Simplified diagram of the involvement of vimentin within SARS-CoV spike-ACE2 complex.
Inactivated SARS Vaccines
The inactivated vaccine is developed to prevent SARS caused by SARS-CoV. This vaccine is used as the first-generation vaccine because it is easy to generate whole killed virus particles. SARS-CoV would inactivate with formaldehyde, UV light, and β-propiolactone which can induce virus-neutralizing antibodies in immunized animals. Besides, the clinical results showed the level of neutralizing antibodies induced by the inoculation with aluminum hydroxide adjuvant was slightly higher than that without adjuvant.
S Protein-based Vaccines
Compared with other three structural proteins encoded by SARS-CoV, spike (S) protein plays an important role in SARS-CoV infection. It can interact with the cellular receptor in order to mediate membrane fusion, allowing viral entry into host cells. Moreover, S protein is a major inducer of neutralizing Abs and protective immunity which prevent SARS-CoV infection. Thus, S protein of SARS-CoV is a key factor for developing SARS vaccines.
There are several recombinant vector-based vaccines expressing SARS-CoV S protein under development. For example, a DNA vaccine encoding the full-length S protein induced neutralizing antibodies can produce higher titers of neutralizing antibodies whatever types of administration is used. The information suggests that the S protein can induce neutralizing antibodies and protective responses in immunized individuals. Therefore, a chimeric vaccine using a replication-defective influenza delNS1 virus as a vector for antigens derived from the SARS-CoV shows the potential to induce immunity against both, influenza virus and SARS-CoV, which have a serious possibility to protect people from SARS infection.
Vaccines Based on Fragments Containing Neutralizing Epitopes
The receptor binding domain (RBD) is a fragment in the middle of S1 subunit of S protein which is responsible for virus binding to the receptor on target cells. RBD includes the major neutralizing epitopes in the S protein of SARS-CoV which could be an ideal SARS vaccine candidate because RBD contains the receptor-binding site, which is critical for virus attachment to the target cell for infection. Therefore, RBD contains the major neutralizing epitopes and can induce potent neutralizing antibody response and protect individuals against SARS-CoV infection. Specifics of antibody for RBD are expected to block binding of virus to the target cell. By comparison, RBD induces higher titers of neutralizing antibodies than those vaccines expressing the full-length S protein. RBD sequences among the late SARS-CoV strains are highly conserved. Antibodies directed against RBD of SARS-CoV isolate may neutralize infection by a broad spectrum of SARS-CoV strains. Thus, recombinant proteins containing RBD or vectors encoding RBD may be used as a candidate vaccine for preventing infection by SARS-CoV with distinct genotypes.
Creative Biolabs is a highly proactive, robust, and diversified company with a strong, scientifically-proven background of viral vaccine development. We have experts who are pleased to share our cutting-edge technology and extensive expertise to help you with the vaccine development of the diseases caused by SARS. If you are interested in our services, please contact us for more details.
Reference
- Yvonne Ting-Chun Yu. (2016). “Surface vimentin is critical for the cell entry of SARS-CoV.” J Biomed Sci. 23(14), 1-8.
All of our products can only be used for research purposes. These vaccine ingredients CANNOT be used directly on humans or animals.
