Comparison of severe acute respiratory syndrome coronavirus and Middle East respiratory syndrome coronavirus reference [1] Weiss S.R, S Navas-Martin. Coronavirus pathogenesis and the emerging pathogen severe acute respiratory syndrome coronavirus

What is coronavirus?

How many categories are there?

What are the symptoms of people who are infected with the coronavirus?

Let’s listen to the answer of Chinese Center for Disease Control and Prevention ~

Pathogenic

1. Overview

Coronavirus belongs to the order of cyst viruses, the family of coronaviruses, and the genus of coronaviruses. It is a class of RNA viruses with cyst membranes and linear single strands of genomes. It is a large category of viruses widely present in nature. The 5' end of the viral genome has a methylated cap-like structure, and the 3' end has a poly(A) tail. The total length of the genome is about 27-32 kb. It is currently the largest genome virus among known RNA viruses.

The coronavirus only infects vertebrates and is associated with a variety of diseases in humans and animals, which can cause respiratory, digestive and neurological diseases in humans and animals.

2. Classification

According to the phylogenetic tree, coronaviruses can be divided into four genera: α, β, γ, and δ, among which β genera coronaviruses can be divided into four independent subgroups A, B, C and D groups.

Coronavirus that can infect humans

So far, in addition to the new coronavirus that caused the outbreak of viral pneumonia in Wuhan, a total of 6 coronaviruses that can infect humans (HCoV-229E, HCoV-OC43, SARS-CoV, HCoV-NL63, HCoV-HKU1 and MERS-CoV) have been found.

HCoV-229E and HCoV-NL63 belong to the alpha coronavirus, HCoV-OC43, SARS-CoV, HCoV-HKU1 and MERS-CoV are all β coronaviruses, among which HCoV-OC43 and HCoV-HKU1 belong to the A subgroup, SARS-CoV belong to the B subgroup, and MERS-CoV belong to the C subgroup (see the figure below).

Animal Coronavirus

includes mammalian coronavirus and avian coronavirus.

Mammalian coronavirus is mainly a α and β coronavirus, and can infect various animals including bats, pigs, dogs, cats, mice, cattle, and horses.

Avian coronavirus is mainly derived from the γ and delta coronaviruses, which can cause diseases of a variety of birds such as chickens, turkeys, sparrows, ducks, geese, pigeons, etc.

Coronavirus phylogenetic tree

3. Physical and chemical characteristics

Human coronavirus is more sensitive to heat. The virus is moderately stable in a suitable maintenance solution of 4℃. It can be stored for several years in -60℃, but as the temperature increases, the virus's resistance decreases. For example, HCoV-229E can lose its infectivity at 56℃ for 10 minutes or 37℃ for several hours. SARS-CoV can survive for 4 days at 37℃, and heating at 56℃ for 90 minutes and heating at 75℃ for 30 minutes can inactivate the virus.

people's coronavirus is not resistant to acids and alkalis, and the most suitable pH value for virus replication is 7.2.

Human coronavirus is sensitive to organic solvents and disinfectants, and 75% alcohol, ether, chloroform, formaldehyde, chlorine-containing disinfectants, peracetic acid and ultraviolet rays can all inactivate the virus.

In the coronavirus, SARS-CoV can survive in urine at room temperature of 24°C for at least 10 days, in sputum and feces of patients with diarrhea for more than 5 days, in blood for about 15 days, and in the surfaces of various objects such as plastic, glass, mosaic, metal, cloth, copy paper, etc. for 2-3 days.

Epidemiology

In the world, 10% to 30% of upper respiratory tract infections are caused by four types of coronaviruses, HCoV-229E, HCoV-OC43, HCoV-NL63 and HCoV-HKU1, accounting for the second most common cold causes, second only to rhinovirus. Infection is seasonal, with the disease prevalence in spring and winter each year. The incubation period is 2-5 days, and the population is generally susceptible. It is mainly transmitted through human contact.

SARS is caused by human infection with SARS-CoV. It first appeared in some areas of Guangdong Province, my country, and then affected 24 provinces, autonomous regions, municipalities directly under the central government and 28 other countries and regions around the world. During the world's first SARS epidemic from November 2002 to July 2003, a total of 8,096 clinically diagnosed cases were reported worldwide, 774 deaths were reported, and the mortality rate was 9.6%. The incubation period of SARS is usually limited to 2 weeks, usually about 2 to 10 days. The population is generally susceptible. SARS patients are the main source of infection. Patients with obvious symptoms are highly contagious, and patients with incubation period or cured are not contagious. Since 2004, no human cases of SARS have been reported worldwide.

MERS is a viral respiratory disease caused by MERS-CoV and was first confirmed in Saudi Arabia in 2012.Since 2012, MERS has spread to 27 countries and regions including , Middle East, , Asia, Europe, etc. So far, a total of 2,468 cases have been reported, with 851 deaths, and the mortality rate is about 34.4%. 80% of the cases come from Saudi Arabia. There has been an imported case of MERS in my country. The incubation period of the disease is 2-14 days, and people are generally susceptible. Dromedary camels are the main storage host of MERS-CoV and are the main source of infection for human cases. The ability to transmit between people is limited. It is currently only found in medical institutions that if effective protection is not taken when in close contact with patients, interpersonal transmission may occur.

Clinical manifestations

Common coronaviruses that can infect humans (including 229E, NL63, OC43 and HKU1 types) usually cause mild or moderate upper respiratory tract diseases, such as colds. Symptoms are mild, mainly including runny nose, headache, cough, sore throat, fever, etc. Sometimes it causes lower respiratory tract diseases such as pneumonia or bronchitis, which are more common among patients with cardiopulmonary disease, people with low immunity, infants and the elderly.

MERS-CoV and SARS-CoV can often cause serious symptoms. Symptoms of MERS usually include fever, cough, shortness of breath, and even progression to pneumonia, with a mortality rate of about 34.4%. Symptoms of SARS usually include fever, chills and body pain, and even progress to pneumonia, with a mortality rate of about 9.6%.

Laboratory Test Methods

Among the six known coronaviruses that can infect humans, the severity and social impact of the disease caused by Middle East Respiratory Syndrome Coronavirus (MERS-CoV) and Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) are far more mature than other coronaviruses.

• Middle East Respiratory Syndrome Coronavirus (MERS-CoV)

Pathogenic testing mainly includes viral isolation and viral nucleic acid testing. Virus isolation is the "gold standard" for laboratory testing. Viral nucleic acid testing can be used for early diagnosis. Various specimens (pharyngeal swab, nasal swab, nasopharyngeal or tracheal extract, sputum or lung tissue, as well as blood and feces) should be retained in time for testing, among which the following respiratory specimens have a higher positive detection rate.

1. Viral nucleic acid detection (PCR). MERS-CoV nucleic acid in respiratory specimens is detected by RT-PCR (preferably real-time RT-PCR).

2. Virus isolate and cultured. MERS-CoV can be isolated from respiratory specimens, but it is generally difficult to separate and cultivate in cells.

• Severe acute respiratory syndrome coronavirus (SARS-CoV)

1. SARS-CoV RNA detection: The criterion for judging positive SARS-CoV RNA is PCR test results that meet one of the following three items can be judged as positive.

(1) requires at least two different sites to test positive for clinical specimens (such as nasopharyngeal secretions and feces).

(2) Collect the same clinical specimen at least 2 days apart and test positive (for example, 2 or more nasopharyngeal secretions).

(3) Use two different methods for the original clinical specimen in each specific assay, or repeat PCR tests starting from the newly extracted RNA of the original specimen. Confirmation of

PCR test results: ① Repeat PCR test using the original specimen; ② Detect the same specimen in the second laboratory.

2. SARS-CoV-specific antigen N protein detection

qualitatively detects SARS-CoV nucleocapsid (N) antigen in serum or plasma samples, and is used for early auxiliary diagnosis of SARS-CoV infection.

3. SARS-CoV specific antibody detection: The specific antibody detection diagnostic SARS standard can be diagnosed as SARS if it meets one of the following two.

(1) Parallel detection of serum antibodies in acute phase and serum antibodies in recovery phase found that antibodies positive.

(2) Parallel detection of serum antibodies in the acute phase and serum antibodies in the recovery phase showed an increase of ≥4 times in antibody titers.Comparison of

Severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV)

References

[1] Weiss S.R, S Navas-Martin. Coronavirus pathogenesis and the emerging pathogen severe acute respiratory syndrome coronavirus[J]. Microbiol Mol Biol Rev, 2005. 69(4): 635-64.

[2] Liu Kezhou . Human viral diseases [M]. Beijing: People's Health Press, 2010:643-665.

[3]http://ictvonline.org/proposals/2008.085-122 V.v4.Coronaviridae.pdf

[4]Yang Yang, Tan Wenjie . Research progress on coronavirus vectors [J]. Acta Virology, 2012.28(03):297-302.

[5] YuDong Yin. MERS, SARS and other coronaviruses as causes of pneumonia[J]. Respirology, 2018,23:130–137.

[6] Shuo Su. Epidemiology, Genetic Recombination, and Pathogenesis of Coronaviruses[J]. Trends in Microbiology, 2016, 24(6):490-502.

[7] "SARS Diagnosis and Treatment Plan (2004 Edition)"

[8] World Health Organization Website. https://www.who.int/zh/news-room/fact-sheets/detail/middle-east-respiratory-syndrome-coronavirus-(mers-cov)

(Source: China Center for Disease Control and Prevention)