Corona Viruses - Current Knowledge - A Review
S. D. Mankar, Dr. R. S. Jadhav, Kapil Gaikwad
Pravara Rural College of Pharmacy, Pravaranagar, 413736.
*Corresponding Author E-mail: sdmankar655@gmail.com
Abstract:
This review aims to establish the current knowledge on Corona viruses by highlighting the recent progress that has been made and comparing it to previous knowledge. Good progress has been made but much still remains unknown and this review has identified some gaps in the current knowledge and made suggestions for consideration in future research. Corona viruses are important human and animal pathogens. Corona viruses (CoVs) are a large group of enveloped viruses with a single-strand RNA genome, which continuously circulate in mammals and birds and pose a threat to livestock, companion animals, and humans. CoVs harboured by avian species are classified to the genera gamma- and delta corona viruses. During epidemics, they are the cause of up to one-third of community-acquired upper respiratory tract infections in adults and probably also play a role in severe respiratory infections in both children and adults. Corona viruses (CoVs) primarily cause enzootic infections in birds and mammals but, in the last few decades, have shown to be capable of infecting humans as well. The outbreak of severe acute respiratory syndrome (SARS) in 2003 and, more recently, Middle-East respiratory syndrome (MERS) has demonstrated the lethality of CoVs when they cross the species barrier and infect humans. A renewed interest in corona viral research has led to the discovery of several novel human CoVs and since then much progress has been made in understanding the CoV life cycle. Recent studies have expanded on its structural motifs and topology, its functions as an ion-channelling viroporin, and its interactions with both other CoV proteins and host cell proteins. The most progress has been made on SARS-CoV E, highlighting specific structural requirements for its functions in the CoV life cycle as well as mechanisms behind its pathogenesis. Data shows that E is involved in critical aspects of the viral life cycle and that CoVs lacking E make promising vaccine candidates.
KEYWORDS: Corona viruses, livestock, enzootic infections.
A novel corona virus, designated 2019-nCoV, was identified as the cause of a cluster of pneumonia cases in Wuhan, a city in the Hubei province of China, at the end of 2019. By late January 2020, thousands of laboratory-confirmed cases in China had been reported, and the case count has been rising daily; the majority of reports are from Hubei and surrounding provinces, but numerous cases have been reported in other provinces and municipalities throughout China, including Beijing. Sporadic but increasing cases have also been reported in other countries globally (including countries in Asia and Europe, as well as Australia, the United States [Washington state, Illinois, California, and Arizona], and Canada), mainly among travelers from China.[1,2,3]
BACKGROUND:
Corona viruses (CoVs) (order Nidovirales, family Corona viridae, subfamily Corona virinae) are enveloped viruses with a positive sense, single-stranded RNA genome. With genome sizes ranging from 26 to 32 kilobases (kb) in length, CoVs have the largest genomes for RNA viruses. Based on genetic and antigenic criteria, CoVs have been organised into three groups: α-CoVs, β-CoVs, and γ-CoVs .Corona viruses primarily infect birds and mammals, causing a variety of lethal diseases that particularly impact the farming industry.[4,5] They can also infect humans and cause disease to varying degrees, from upper respiratory tract infections (URTIs) resembling the common cold, to lower respiratory tract infections (LRTIs) such as bronchitis, pneumonia, and even severe acute respiratory syndrome (SARS). In recent years, it has become increasingly evident that human CoVs (HCoVs) are implicated in both URTIs and LRTIs, validating the importance of corona viral research as agents of severe respiratory illnesses. Corona viruses mainly circulate among other animals but have been known to evolve and infect humans as in the cases of severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS) together with four further corona viruses that cause mild respiratory symptoms similar to the common cold[6,7]All corona viruses known to infect humans have been shown to spread between people. Transmission of corona viruses is primarily thought to occur among close contacts via respiratory droplets generated by sneezing and coughing.[8,9]
Epidemiology:
A novel corona virus, designated 2019-nCoV, was identified as the cause of a cluster of pneumonia cases in Wuhan, a city in the Hubei province of China, at the end of 2019. By late January 2020, thousands of laboratory-confirmed cases in China had been reported, and the case count has been rising daily; the majority of reports are from Hubei and surrounding provinces, but numerous cases have been reported in other provinces and municipalities throughout China, including Beijing.[10,11]
Epidemiologic investigation in Wuhan identified an initial association with a seafood market where most patients had worked or visited and which was subsequently closed for disinfection. The seafood market also sold live rabbits, snakes, and other animals. However, as the outbreak progressed, most laboratory-confirmed cases had no contact with this market, and cases were identified among health care workers and other contacts of patients with 2019-nCoV infection. Human-to-human transmission has been confirmed in China and has also been identified in other countries, including the United States.[12,13] Understanding of the transmission risk is incomplete. One report of a small cluster of five cases suggested transmission from asymptomatic individuals during the incubation period; all patients in this cluster had mild illness.[14]
Structure:
The CoV E protein is a short, integral membrane protein of 76–109 amino acids, ranging from 8.4 to 12 kDa in size. The primary and secondary structure reveals that E has a short, hydrophilic amino terminus consisting of 7–12 amino acids, followed by a large hydrophobic transmembrane domain (TMD) of 25 amino acids, and ends with a long, hydrophilic carboxyl terminus, which comprises the majority of the protein. The hydrophobic region of the TMD contains at least one predicted amphipathic α-helix that oligomerizes to form an ion-conductive pore in membranes.[15]
Sign and Symptoms
The illness is characterized primarily by fever, cough, dyspnea, and bilateral infiltrates on chest imagine. The incubation period of 2019-nCoV is thought to be within 14 days following exposure. Although many of the reported infections are not severe, approximately 20 percent of confirmed patients have had critical illness (including respiratory failure, septic shock, or other organ failure requiring intensive care). Most of the fatal cases have occurred in patients with underlying medical comorbidities.
Upper respiratory symptoms such as sneezing, a runny nose or sore throat are less frequent.
The time from exposure to onset of symptoms is estimated at 2 to 10 days by the World Health Organization and 2 to 14 days by the US Centers for Disease Control and Prevention (CDC).
Among the first 41 confirmed cases admitted to hospitals in Wuhan, 13 (32%) individuals had another chronic condition, like diabetes or hypertension. Overall, 13 (32%) individual’s required intensive care, and 6 (15%) individuals died[54] Many of those who died had other conditions such as advanced age, hypertension, diabetes, or cardiovascular disease that impaired their immune systems.[16]
Causes:
The spread of the virus between people has been variable, with some affected people not transmitting the virus to others while others have been able to spread the infection to several people. There have been various estimates for the basic reproduction number, ranging from 2.13 to 3.11. The number describes how many people a newly infected person is likely to pass the virus onto. The new corona virus has been reportedly able to transmit down a chain of up to four people so far. This is similar to severe acute respiratory syndrome-related corona virus (SARSCoV). Respiratory corona viruses probably spread in a fashion similar to that of rhinoviruses, via direct contact with infected secretions or large aerosol droplets. Immunity develops soon after infection but wanes gradually over time. Reinfection is common, presumably because of waning immunity, but possibly because of antigenic variation within species. In children hospitalized in New York City with HCoV infection and respiratory disease, a majority were under five years of age and had some underlying condition such as heart disease, chronic lung disease, or congenital abnormalities[16,17]
Diagnosis:
The most useful method for laboratory diagnosis is to collect paired sera (from the acute and convalescent phases of the disease) and to test by ELISA for a rise in antibodies against OC43 and 229E. Complement fixation tests are insensitive; other tests are inconvenient and can be used only for one serotype. Direct hybridization and polymerase chain reaction tests for viral nucleic acid have been developed and, particularly with the latter, are the most sensitive assays currently available for detecting virus. If you are experiencing symptoms, you should tell your healthcare provider about any recent travel or contact with animals. Most MERS-CoV infections have been reported from countries in the Arabian Peninsula. Therefore reporting a travel history or contact with camels or camel products is very important when trying to diagnose MERS. Colds caused by corona viruses cannot be distinguished clinically from other colds in any one individual. Laboratory diagnosis may be made on the basis of antibody titers in paired sera. The virus is difficult to isolate. Nucleic acid hybridization tests (including PCR) are now being introduced.[18]
Precaution:
There is currently no vaccine to prevent 2019-nCoV infection. The best way to prevent infection is to avoid being exposed to this virus. However, as a reminder, CDC always recommends everyday preventive actions to help prevent the spread of respiratory viruses, including:
· Wash your hands often with soap and water for at least 20 seconds, especially after going to the bathroom; before eating; and after blowing your nose, coughing, or sneezing.
· If soap and water are not readily available, use an alcohol-based hand sanitizer with at least 60% alcohol. Always wash hands with soap and water if hands are visibly dirty.
· Avoid touching your eyes, nose, and mouth with unwashed hands.
· Avoid close contact with people who are sick.
· Stay home when you are sick.
· Cover your cough or sneeze with a tissue, then throw the tissue in the trash.
· Clean and disinfect frequently touched objects and surfaces using a regular household cleaning spray or wipe.[19]
Treatment:
There are no specific treatments for illnesses caused by human corona viruses. Most people with common human corona virus illness will recover on their own. However, you can do some things to relieve your symptoms
· Take pain and fever medications (Caution: do not give Aspirin to children)
· Use a room humidifier or take a hot shower to help ease a sore throat and cough
If you are mildly sick, you should
· Drink plenty of liquids
· Stay home and rest
If you are concerned about your symptoms, you should see your healthcare provider.[20]
REFERENCES:
1. Corona virus cases rise to 571 in Chinese mainland. January 23, 2020. http://en.nhc.gov.cn/2020-01/23/c_76004.htm (Accessed on January 23, 2020).
2. European Centre for Disease Prevention and Control. Novel corona virus in China. https://www.ecdc.europa.eu/en/novel-coronavirus-china (Accessed on January 23, 2020).
3. WHO Disease outbreak news: Novel Corona virus – Republic of Korea (ex-China). January 21, 2020. https://www.who.int/csr/don/21-january-2020-novel-coronavirus-republic-of-korea-ex-china/en/ (Accessed on January 21, 2020).
4. First Travel-related Case of 2019 Novel Corona virus Detected in United States, January 21, 2020. https://www.cdc.gov/media/releases/2020/p0121-novel-coronavirus-travel-case.html (Accessed on January 21, 2020).
5. Second Travel-related Case of 2019 Novel Corona virus Detected in United States, January 24, 2020. https://www.cdc.gov/media/releases/2020/p0124-second-travel-coronavirus.html (Accessed on January 24, 2020).
6. European Centre for Disease Prevention and Control. Geographical distribution of 2019-nCov cases. https://www.ecdc.europa.eu/en/geographical-distribution-2019-ncov-cases (Accessed on January 26, 2020).
7. World Health Organization. Novel corona virus situation report-2. January 22, 2020. https://www.who.int/docs/default-source/coronaviruse/situation-reports/20200122-sitrep-2-2019-ncov.pdf (Accessed on January 23, 2020).
9. International Committee on Taxonomy of Viruses. http://ictvonline.org/virusTaxonomy.asp (Accessed on May 21, 2015).
11. Masters PS, Perlman S. Corona viridae. In: Fields Virology, 6th ed, Knipe DM, Howley PM, Cohen JI, et al (Eds), Lippincott Williams and Wilkins, a Wolters Kluwer business, Philadelphia 2013. Vol 2, p.825.
12. McIntosh K, Peiris JSM. Corona viruses. In: Clinical Virology, 3rd ed, Richman DD, Whitley RJ, Hayden FG (Eds), ASM Press, Washington, DC 2009. p.1155.
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Received on 04.02.2020 Modified on 01.03.2020 Accepted on 26.03.2020 ©A and V Publications All right reserved Research J. Science and Tech. 2020; 12(2): 163-166. DOI: 10.5958/2349-2988.2020.00021.2 |
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