Merbecovirus

Merbecovirus is a subgenus of viruses in the genus Betacoronavirus, which is part of the family Coronaviridae and the order Nidovirales. This subgenus includes several species of coronaviruses that are known to infect humans and animals, with the most notable being the Middle East respiratory syndrome-related coronavirus (MERS-CoV).

Virology

Merbecoviruses are enveloped, positive-sense, single-stranded RNA viruses. They have a large genome, typically ranging from 26 to 32 kilobases in length. The virions are spherical with a diameter of approximately 120-160 nm. The surface of the virus is covered with spike (S) glycoproteins, which are responsible for binding to host cell receptors and facilitating viral entry.

Genome and Structure

The genome of Merbecoviruses is organized into several open reading frames (ORFs). The first two-thirds of the genome encodes the replicase complex, which is responsible for viral RNA synthesis. The remaining third encodes structural proteins, including the spike (S), envelope (E), membrane (M), and nucleocapsid (N) proteins, as well as several accessory proteins that may play roles in pathogenesis and immune evasion.

Replication Cycle

Merbecoviruses enter host cells by binding to specific receptors on the cell surface. For MERS-CoV, the receptor is Dipeptidyl peptidase-4 (DPP4), also known as CD26. After binding, the virus is internalized, and the viral RNA is released into the cytoplasm. The replicase complex synthesizes a full-length negative-sense RNA template, which is then used to produce new positive-sense genomic RNA and subgenomic mRNAs. These mRNAs are translated into viral proteins, which assemble into new virions that are released from the host cell to infect new cells.

Pathogenesis

Merbecoviruses can cause a range of diseases in humans and animals. MERS-CoV, for example, causes Middle East respiratory syndrome (MERS), a severe respiratory illness with symptoms including fever, cough, and shortness of breath. The virus can also cause gastrointestinal symptoms and, in severe cases, lead to pneumonia, acute respiratory distress syndrome (ARDS), and multi-organ failure.

Epidemiology

MERS-CoV was first identified in Saudi Arabia in 2012. Since then, it has been reported in several countries, primarily in the Middle East. The virus is believed to have originated in bats and is transmitted to humans through contact with infected dromedary camels. Human-to-human transmission can occur, particularly in healthcare settings.

Prevention and Control

Preventive measures for Merbecoviruses include avoiding contact with infected animals, practicing good hygiene, and implementing infection control measures in healthcare settings. There is currently no specific antiviral treatment or vaccine for MERS-CoV, although several candidates are in development.

Also see

• Middle East respiratory syndrome-related coronavirus
• Betacoronavirus
• Coronavirus
• Nidovirales