What is MERS?
MERS is Middle East respiratory syndrome, also known as camel flu, caused by a lethal zoonotic virus MERS-CoV. People may achieve the virus through contact with the camel. The first case was reported from Jeddah,2012. From then on, other cases were reported from other countries. Since September 2012, 27 countries have reported cases of MERS-CoV.
The symptoms of MERS range from mild to severe, including fever, cough, shortness of breath and further pneumonia.The fatality rate is higher than 30%. As of 2020 there is no specific vaccine or treatment for the disease, a number of antiviral medications were being studied.
MERS-CoV, also called EMC/2012 (HCoV-EMC/2012), is a novel positive-sense, single-stranded RNA virus of the genus β-CoV .
MERS-CoV has the capability of infecting multiple human cell lines. Among them, espiratory epithelial cells are highly susceptible.Kidneys are also significantly affected by MERS-CoV, in addition to intestinal, liver cells, and histiocytes.
The genome of MERS-CoV contains 30,119 nucleotides and a minimum of 10 predicted open reading frames. ORF1a and ORF1b are the replicase opening frames which cover the 5′ end region of the genome, while the 3′ end encodes structural proteins, including spike (S), membrane (M), nucleocapsid (N), envelope (E), as well as various accessory proteins such as 3, 4a, 4b, 5 and 8b.
The spike (S) protein of β-CoV is a key in cross-species transmission as it mediates virus-receptor recognition and induces viral pathogenesis. The receptor binding domain (RBD) on S protein's N-terminal is vital for the penetration of β-CoV into host cells. Further, the severity of infection and cross-species efficiency is influenced by the mutations in CoV RBD.
The functional receptor of MERS-CoV is dipeptidyl peptidase 4 (DPP4) and its expression induces the infection.
(Ref: Nour Ramadan, Houssam Shaib.Middle East respiratory syndrome coronavirus (MERS-CoV): A review.GERMS.2019)