ABSTRACT
Adenovirus vectors have been employed to develop a vaccine against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) for curtailing the Covid-19 pandemic spreading. Many different viral vectors have been mainly targeting the SARS-CoV-2 spike (S) protein as an antigen. Spike (S) protein is comprised of S1 and S2 subunits, in which the receptor-binding domain (RBD) of S1 is responsible for recognizing and engaging with its host cellular receptor protein angiotensin-converting enzyme 2 (ACE2), S2 accounts for membrane fusion of virus and host cell. Chimpanzee adenovirus was also used as a vector vaccine for SARS-CoV-2 (ChAdSARS-CoV-2-S) by intramuscular injection, and intranasal administration has been tested. Adenovirus vector-based vaccines are the most advanced, with several vaccines receiving Emergency Use Authorization (EUA). It was shown that rhesus macaques were protected from SARS-CoV-2 challenge after a month of being vaccinated with ChAd-SARS-CoV-2-S. A single intranasal or two intramuscular ChAd-SARSCoV-2-S vaccines could induce humoral antibodies and T cell responses to protect the upper and lower respiratory tract against SARS-CoV-2. As the effectiveness was demonstrated in non-human primates, ChAd-SARS-CoV-2-Sa potential option for preventing SARS-CoV-2 infection in humans. However, detecting novel more transmissible and pathogenic SARS-CoV-2 variants added concerns about the vaccine efficacy and needs monitoring. Moreover, the cause of recently documented rare cases of vaccine indicated immune thrombotic thrombocytopenia. This review article provided details for the adenovirus vector vaccine for SARS-CoV-2 in humans and tried to provide solutions to the adenovirus vector hemagglutinin issueCopyright © 2023, World's Veterinary Journal.All Rights Reserved.
ABSTRACT
Background: Currently, the present world is facing a new deadly challenge from a pandemic disease called COVID-19, which is caused by a coronavirus named SARS-CoV-2. To date, no drug or vaccine can treat COVID-19 completely, but some drugs have been used primarily, and they are in different stages of clinical trials. This review article discussed and compared those drugs which are running ahead in COVID-19 treatments. Method(s): We have explored PUBMED, SCOPUS, WEB OF SCIENCE, as well as press releases of WHO, NIH and FDA for articles related to COVID-19 and reviewed them. Result(s): Drugs like favipiravir, remdesivir, lopinavir/ritonavir, hydroxychloroquine, azithromycin, ivermectin, corticosteroids and interferons have been found effective to some extent, and partially approved by FDA and WHO to treat COVID-19 at different levels. However, some of these drugs have been disapproved later, although clinical trials are going on. In parallel, plasma therapy has been found fruitful to some extent too, and a number of vaccine trials are going on. Conclusion(s): This review article discussed the epidemiologic and mechanistic characteristics of SARS-CoV-2, and how drugs could act on this virus with the comparative discussion on progress and drawbacks of major drugs used till date, which might be beneficial for choosing therapies against COVID-19 in different countries.Copyright © 2022 Bentham Science Publishers.
ABSTRACT
Background: The CVnCoV (CureVac) mRNA vaccine for SARS-CoV-2 has recently been evaluated in a Phase IIb/III efficacy trial in humans. CV2CoV is a second-generation mRNA vaccine with optimized non-coding regions and enhanced antigen expression. Methods: Here we report a head-to-head study of the immunogenicity and protective efficacy of CVnCoV and CV2CoV in nonhuman primates. We immunized 18 cynomolgus macaques with two doses of 12 ug of lipid nanoparticle formulated CVnCoV, CV2CoV, or sham (N=6/group). Results: CV2CoV induced substantially higher binding and neutralizing antibodies, memory B cell responses, and T cell responses as compared with CVnCoV. CV2CoV also induced more potent neutralizing antibody responses against SARS-CoV-2 variants, including B.1.351 (beta), B.1.617.2 (delta), and C.37 (lambda). While CVnCoV provided partial protection against SARS-CoV-2 challenge, CV2CoV afforded robust protection with markedly lower viral loads in the upper and lower respiratory tract. Antibody responses correlated with protective efficacy. Conclusion: These data demonstrate that optimization of non-coding regions can greatly improve the immunogenicity and protective efficacy of an mRNA SARS-CoV-2 vaccine in nonhuman primates.