![]() Moreover, a rabies-based vaccine against SARS-CoV-2 is currently being evaluated in humans 28. The RABV vaccine has been shown to elicit long-lasting immunity in humans 27, which is important for a vaccine platform. Both vectors can be used as inactivated vaccines that will elicit immune responses against both foreign glycoproteins and the native rhabdoviral glycoproteins 22, 23, 24, 25 however, VSV has never been tested as a killed vector. These vectors have many advantages, including their small, easily manipulated genome that can stably express foreign glycoproteins 20, 21 and their well-established safety profiles 22, 23, 24, 25, 26. Rhabdoviruses, specifically rabies virus (RABV) and VSV, have been used as vaccine vectors for a variety of infectious diseases 19, including CCHFV, as mentioned above 9. Thus, there is still a great need for an effective and safe CCHFV vaccine strategy. While live vaccine strategies can be effective, there is always a concern about the virulence (whether inherent or mutation acquired) of these vectors, especially when used in immunocompromised people, pregnant women, and children. ![]() Finally, both live Modified Vaccinia Ankara (MVA) and Vesicular Stomatitis virus (VSV) vaccines containing the CCHFV-M gene protected mice from CCHFV challenge 9, 18, but supporting clinical studies are pending. However, the study did not investigate the longevity of the immune responses elicited by the vaccine, which might be a problem based on the findings of waning humoral immune response to the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) mRNA vaccine 17. A nucleoside-modified mRNA vaccine using CCHFV nucleoprotein and/or glycoproteins also showed 100% protection in mice 10. DNA vaccines using both the nucleoprotein (S) gene, glycoprotein (M) gene, or a combination of these antigens have demonstrated 100% protection in mice or Cynomolgus macaques 13, 14, 15, 16, but DNA vaccines have not been effective in humans. A cell culture produced whole inactivated virus vaccine showed 80% protection in mice 12 however, it requires a BSL-4 facility for production, which is dangerous and expensive. While many other strategies have proven to be protective in animal models 8, 9, 10, there are concerns regarding the clinical application of each candidate. The only vaccine ever tested in humans was a whole inactivated virus vaccine propagated in mouse brains that reduced cases in Bulgaria, but requires BSL-4 laboratories for production and is administered as a four dose regimen 11. ![]() There have been a variety of vaccine strategies against CCHFV tested in animal models with varying success 8, 9, 10. Accordingly, CCHFV is classified as an NIH/NIAID Category A and World Health Organization (WHO) high-priority pathogen. Therefore, CCHFV is designated as a biosafety level 4 (BSL-4) pathogen, further highlighting the need for effective vaccines and therapeutics. The case-fatality rate for CCHF is up to 40% 1, 2, 3, 4, 5, and there are no licensed CCHFV-specific vaccines or treatments available for humans. However, CCHFV can cause Crimean-Congo hemorrhagic fever (CCHF) in humans, which first presents with flu-like symptoms and progresses to bleeding, petechiae, and, in more severe cases, organ failure and death 1, 2, 3, 4, 5. CCHFV infects a wide range of mammalian hosts, yet it does not cause visible disease in these animals 1, 2, 3, 4, 5. ![]() Areas where this tick can survive are increasing due to anthropogenic factors such as habitat modification, thus increasing the areas where CCHFV can circulate 6, 7. The wide range of endemic areas is due to the natural habitat of CCHFV’s tick vector, ticks of the Hyalomma genus 1, 2, 3, 4, 5. Crimean-Congo Hemorrhagic Fever Virus (CCHFV) is an emerging infectious disease with an extensive global distribution spanning across areas of Africa, Asia, the Middle East, and Europe 1, 2, 3, 4, 5. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |