Abstract

         Coronaviruses (CoV) are a family of virus causing illness such as simple cold to Severe Acute Respiratory Syndrome(SARS-CoV). Vert recently, novel cases of pneumonia were detected in the Wuhan City of China. The causative virus is a novel coronavirus (2019-nCov) which is a new strain that has not been reported in humans so far. This review aims to provide information on the 2019-nCov virus about its origin, structure, mode of transmission and measure the people should take to avoid its infection in order to control the disease.

Keywords: Coronavirus, 2019-nCoV, Wuhan, Zoonotic, Bat.

Introduction

         Coronaviruses (CoV) causes illness starting from mere cold to adverse respiratory diseases like Middle East Respiratory Syndrome (MERS-CoV) and Severe Acute Respiratory Syndrome (SARS-CoV). On 31^st December 2019, cases of pneumonia of unknown etiology (unknown cause) were detected in Wuhan City, Hubei Province of China. This was a symptom of attack belonging to a type of coronavirus, which was declared officially by the Chinese authorities on 7^th January. The virus was a new strain of coronavirus family which was not reported in humans before. Hence named as “novel coronavirus” (2019-nCoV). The 2019-nCoV is still under surveys to know about its source of the outbreak, mode(s) of transmission as well as the extent of infection. The studies on the 2019-nCoV virus and previous experience with the MERS-CoV and SARS-CoV suggested that they could be zoonotic (Chen et al., 2020).

2019 novel coronavirus (2019-nCov)

         The 2019 CoVs are spherical or pleomorphic shaped virus enveloped by club shaped glycoprotein projections having a single-standard (postive-sense) RNA as its genetic material associated with a nucleoprotein within a capsid encompassed of matrix protein (Fig.1). After infecting a host cell the virus gets ttanscribed with the host genome and gets translated. The translated mRNAs share a common 3' end, through which new virtons get budded from the host cell membranes. The virus gets transmitted through airbone droplets from infected persons cough or sneeze. The virus sticks in the nasal mucosa and replication locally in the ciliated epithellum leading to cellular damage and inflammmation. Infected host develops an antibody in the serum and the developed immunity diminishes after a year ro two(Tyrrell and Myint, 1996).

Figure 1: Structure of novel coronavirus

Source: wiki-images

         Common symptoms of infection mainly include respiratory symptoms, cough, fever, and shortness of breath. In more severe cases, it results in severe acute respiratory syndrome/pneumonia, kidney failure and even death (Fig. 2) The virus can be even asymptomatic until 14 days. It can get expressed in the host body even at day one of DNA invasion as well. Normally the fever lasts from first day till a week. People who recover usually would not get to the stage of pneumonia and respiratory syndrome, which would be developed on 4th or 5th day of infection (Chen et al., 2020 and Huang et al., 2020).

Figure 1: Symptoms of disease

Source: https://www.siasat.com/

         Laboratory diagnosis is based through the antibody titers in paired sera. The presence of 2019-nCoV in respiratory specimens are analyzed by the next generation sequencing or real-time RT-PCR methods. The primers 5′-ACTTCTTTTTCTTGCTTTCGTGGT-3′ (forward) and 5′-GCAGCAGTACGCACACAATC-3′ (reverse) are probed with the target 5′CY5-CTAGTTACACTAGCCATCCTTACTGC-3′BHQ1 to envelope gene of CoV for diagnosing (Lu et al., 2019). Scientists are still working hard to develop antivirals for the coronavirus. The present treatment includes use of some immune boosters which can accelerate the host immune power to fight against the disease (Wu et al., 2020).

Genome sequencing of the virus

         Genetic sequencing of the Wuhan coronavirus could add on to the origins and spread of the deadly virus. Various laboratories in China and Thailand have sequenced the genomes of more than 25 strains of infected people which are publicly available now. Evolutionary genetics are using the data to find the emerengency of the virus and to identify any genetic vicissitudes that would have helped the virus to jump form animals to humans enlabing it to spread more efficently. The phylogenetic analysis of these sequences suggests that the Wuhan virus is related to coronaviruases that circulate in bats like SARS and its close relatives (Fig. 3). But other mammals like mice can also transmit these viruses.

Figure 1: Phylogenetic tree showing the relationship of 2019-nCoV with bat and mice genomes ( Lu et al., 2020)

Virulence of the virus

         High rates of pneumonia in initially infected people made researchers to conclude it as highly malignant. However, these regressed slightly, as milder cases have turned up. With the average death of 1 in 45, the virulence was found to be lesser and deady compared to SARS, which killed around 10% of the infected people (Source: asia.nikkei.com).

Transmission rate of the virus

         Another question among scientists is how extensively asymptomatic people can be infectious to others. In a study by Chan et al. (2020) on a cluster of six infections in a family in Shenzhen identified a child who was asymptomatic carrying the virus. If such cases are common, control of the disease is tough. Moreover, the study revealed that the most favorable season for the coronavirus transmission is in winters.

R0 evaluation

         R0 is defined as the average number of secondary cases generated by a single primary case in a large previously unexposed host population and its value tells us a great deal about the epidemiology of a pathogen. R0 = 0 indicates no spread in that population; this value would apply to zoonotic infections that do not spread between humans. For the Wuhan coronavirus, R0 is found to be 1.5-2.2, which could enhance the chance of spread of the disease (Chen et al., 2020).

Control of the viruses

         Treatment of common cold is symptomatic but still, no specific drugs or vaccines are available for the ailment. Hygiene measures could reduce the rate of transmission. Standard recommendations to prevent the infection include regular hand washing, covering of mouth and nose while coughing and sneezing, usage of face protection masks, thoroughly cooking meat and eggs, Avoiding close contact as coughing and sneezing.

Present Statistics

         The whole of china has been infected drastically by the disease within a time gap of a month. The disease has spread worldwide as well. The epidemiology of the deadly novel coronavirus infection is worldwide and the WHO has categorized the viral attack as a “pandemic”.

Conclusion

         The review was to throw light on the novel coronavirus, its structure, symptoms, diagnosis and treatment and control measures. In scientific world though new drugs are developed there are still many diseases unable to cure. Despite many challenges faced by mankind there are still need for the development of novel drugs against the deadly diseases as at present for 2019-nCoV.

References

Chan, J. F. W., Yuan, S., Kok, K. H., To, K. K. W., Chu, H., Yang, J and Tsoi, H. W. (2020). A familial cluster of pneumonia associated with the 2019 novel coronavirus indicating person-to-person transmission: a study of a family cluster. The Lancet, 395 (10223): 514-523.

Chen, N., Zhou, M., Dong, X., Qu, J., Gong, F., Han, Y and Yu, T. (2020). Epidemiological and clinical characteristics of 99 cases of 2019 novel coronavirus pneumonia in Wuhan, China: a descriptive study. The Lancet, 395 (10223): 507-513.

Huang, C., Wang, Y., Li, X., Ren, L., Zhao, J., Hu, Y and Cheng, Z. (2020). Clinical features of patients infected with 2019 novel coronavirus in Wuhan, China. The Lancet, 395 (10223): 497-506.

Lu, R., Zhao, X., Li, J., Niu, P., Yang, B., Wu, H and Bi, Y. (2020). Genomic characterisation and epidemiology of 2019 novel coronavirus: implications for virus origins and receptor binding. The Lancet, 395 (10224): 565-574.

Tyrrell, D. A and Myint, S. H. (1996). Coronaviruses. In Medical Microbiology. 4^th edition. University of Texas Medical Branch at Galveston.

Wu, J. T., Leung, K. and Leung, G. M. (2020). Nowcasting and forecasting the potential domestic and international spread of the 2019-nCoV outbreak originating in Wuhan, China: a modelling study. The Lancet, 395 (10225): 689-697.

Image The Facts Corona Virus

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