Virology

CORONAVIRIDAE FAMILY

Written by MicroDok

Coronaviridae family is comprised of viruses known as coronaviruses. There are only two genera of viruses in the Coronaviridae family. Coronavirus (which contain Coronaviruses) and Torovirus (which contain Toroviruses) are the two main genera of Coronaviridae family. Both coronaviruses and toroviruses have a worldwide distribution. Viruses in this family include those that infect humans and other mammals such as pigs, mice, cattle, birds and bats. Coronaviruses are enveloped viruses that replicate in the cytoplasm of their host cell. Coronavirus are released from their host cell by a budding process via the cell membrane after completing the cycle of their replication in affected host cell. They have a ss(+)RNA genome and coronaviruses measure between 120-160 nm in diameter. Coronaviruses have a helical nucleocapsid. Viruses in this family cause respiratory infections in humans and other animals that they infect.

The commonest viral member of the Coronaviridae family used to be severe acute respiratory syndrome coronavirus (SARS-CoV)– that causes a severe respiratory infection or lung disease that is characterized by pneumonia of the lower respiratory tract of humans. Now, there is a new strain of coronavirus known as severe acute  respiratory syndrome coronavirus strain 2 (SARS-CoV-2) that causes coronavirus disease 2019 otherwise known as COVID-19. In 2003, SARS coronavirus caused several outbreaks of SARS in most parts of the world; and the epidemic was marked by several morbidity and mortality especially in hospital environments and amongst healthcare practitioners who had direct contact with cases of SARS. The first outbreak of SARS actually occurred in the Chinese city of Guangzhou province in 2002 from where the world outbreak of the disease started from. Aside the lower respiratory tract of humans which SARS coronavirus is known to colonize, the virus also attack the gastrointestinal tract and neurological tissues of the body. The main routes via which coronaviruses are transmitted are via aerosols, body contact and through the oral-feacal route (especially for some toroviruses that infect animals).

But the main major route via which SARS coronaviruses are spread in human population is via the respiratory tract of infected individuals especially when they cough and sneeze. SARS coronavirus infection in humans has an incubation period of 2-7 days and infected individuals are highly infectious especially when they present with respiratory symptoms that characterize the disease. Common cold, malaise, and fever are some of the asymptomatic symptoms of SARS; and when individuals become very symptomatic, infected individuals have myalgia, dry throat and even shortness of breath. No specific antiviral therapy exists for the treatment of SARS in humans. However, the management of the disease is mainly based on supportive therapy.

The second strain of coronavirus is SARS-CoV-2 (severe acute respiratory syndrome coronavirus strain 2) tha causes COVID-19. Coronavirus disease (COVID-19) is an infectious disease caused by a newly discovered coronavirus strain known as SARS-CoV-2. Most people infected with the COVID-19 virus will experience mild to moderate respiratory illness and recover without requiring special treatment.  However, older people and those with underlying medical problems like cardiovascular disease, diabetes, chronic respiratory disease, and cancer are more likely to develop serious illness and may die from COVID-19 if proper medical care is not given. Coronavirus disease 2019 (COVID-19) is a pneumonia-like respiratory tract disease that is caused by SARS-CoV-2 as aforementioned, and the disease is usually spread via droplets that emanate from the mouth or nose when infected persons cough, talk or sneeze. SARS-COV-2 is a new strain of coronavirus that was first discovered in Wuhan, China where the first cases had their symptom onset in December, 2019. SARS-CoV-2 is a novel strain of virus in the family or genera of viruses known as Coronaviridae or Coronaviruses. The first strain is SARS-CoV (severe acute respiratory syndrome coronavirus) – which caused SARS in the world in the early 2000, starting from China. SARS-CoV-2 is the only known strain to cause COVID-19 at the moment; and this strain of coronavirus is more infectious than SARS-CoV – owing to the rate of spread and morbidity and mortality associated with SARS-CoV-2 around the globe. COVID-19 pandemic has resulted in a global crisis with short- and long-term implications for health, the economy, and social relations.

SARS-CoV-2 is a novel viral strain of coronavirus and thus the biology, pathophysiology and pathogenesis of the virus is still unraveling as scientists are now faced with finding a functional cure and vaccine for the pandemic that have ravaged the economy of the world.

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