IntroductionOne of the families of ssRNA viruses that cause upper respiratory tract disease in humans and birds is the Coronaviridae family. Although coronaviruses have been known since the early 1960s (virus 229 and OC43), they only began to attract attention in 2003, when a virus causing a syndrome was discovered in an epidemic in southern China. severe acute respiratory disease (SARS) and then spread to several countries.1 Ten years after this event, which was responsible for 774 deaths in over 30 countries (out of 8,000 confirmed cases), a new “SARS-like” infection emerged from the Middle East and was named Middle East respiratory syndrome coronavirus (MERS-CoV) by the Coronavirus Study Group of the International Committee on Taxonomy of Viruses. Samples from two patients with severe cases of community-acquired pneumonia (Bisha, KSA and Doha, Qatar) contributed to the first isolation of the new virus and its sequencing.2 The new virus was isolated several more times from locals and tourists from the Arabian Peninsula who presents symptoms similar to those of the first documented victims of the disease. In retrospect, a cluster of respiratory infections that occurred previously in Jordan (April 2012) were related to this viral agent.3 Genome analysis of MERS-CoV classified the emerging virus as a member of the C lineage of the Betacoronavirus genus. Interestingly, its closest known relatives are present in bats (HkU-4 and HkU-5). In contrast, it is more distantly related to SARS-CoV not only genetically, but also in terms of its use of the virus's receptors.3Structure and composition of the virionAll coronaviruses have four structural proteins in common (Figure 1): a large surface glycoprotein (S; 1150–1450 ami...... middle of paper ......Lancet Infect 9, 291–300 (2009).10. MERS-CoV WHO summary updates at11. Middle East respiratory syndrome - MERS-CoV at12. Zhou, N., Zhang, Y., Zhang, J.-C., Feng, L. & Bao, J.-K. Dawn of vaccine development and treatment. Med. 113, 143–147 (2014).13. Middle East Respiratory Syndrome Coronavirus. Dis. 20, 1054–1056 (2014).14. (John Wiley & Sons, Ltd, 2004).