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| Combating COVID-19 | | |
Dr. Banarsi Lal and Dr. Vikas Tandon
A virus is a biological agent that reproduces inside the cells of living hosts. Viruses are not new and they affect not only to human beings but animals and plants also. After infection, the host cell is forced to reproduce thousands of similar identical copies of original virus. A virus has the ability to mutate and evolve. Scientists have discovered more than 4800 species of viruses. Their size ranges between 20 to 300 nanometers. Viruses vary in shape. Some are simple helical and icosahedral to more complex structures. A virus is made up of a core of genetic material, either DNA or RNA surrounded by a protective coat called a capsid which is made up of protein. It is a nucleic acid (DNA or RNA) wrapped in a coat of proteins, some attached to sugars (glycoproteins). Viruses spread in different ways. Plants viruses are spread from plant- to- plant by the insects and other organisms known as the vectors. Some viruses of humans and animals are spread by the infected bodily fluids. Some viruses are spread by the air and faecal-oral route. Rotavirus is spread by the direct contact with the infected children. Others such as dengue virus is spread by the blood sucking insects. Viruses can cause diseases to human beings, animals and plants. In human beings and animals viruses are eliminated by the immune system of the body. Moreover, antiviral drugs are also given to prevent the life threatening infections caused by the viruses.
The year 2020 began with a rapid, global pandemic Coronavirus (COVID-19).This virus has given a global health threat. It is a highly contagious virus and has been spread in all the continents except Antarctica. Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has emerged from Hubei province in China in late 2019.COVID-19 has been categorised as the pandemic and it has created havoc across the globe. Now-a-days we are listening from everywhere about this virus. This virus has spread across the globe in a very short period causing a great damage all over the world. It indicates its transmissibility, morbidity and mortality. Current outbreak of COVID-19 has created a curiosity to understand this deadly virus. Some species spread coronaviruses without becoming sick, like the camels that carry MERS and bats which carry many viruses. Before the end of 2019, six coronaviruses were known to cause diseases in the human beings. Four of these were endemic around the world. The viruses known as human coronavirus hCoV-HKU1, (hCoV)-229E, hCoV-NL63 and hCoV-OC43 are of little concern at a global public health level but the other two viruses have done the great damage among the human beings. Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) emerged in the human population in 2002. This virus from a bat was transmitted via a palm civet to infect a human in the Guangdong province of China causing infection to over 8,000 people. Its infection was stopped in 2003 and after that the virus was not seen. Another epidemic coronavirus, called as Middle East Respiratory Syndrome Coronavirus (MERS-CoV), emerged in 2012.This virus transmitted from a bat via a camel to human beings. Like the SARS-CoV outbreak, MERS-CoV started with a patient suffering with pneumonia. Middle East Respiratory Syndrome Coronavirus showed far more limited human-to-human transmission than SARS-CoV. MERS-CoV mostly confined to regions of the Middle East. The number of cases of MERS-CoV were low and the Case Fatality Ratio (CFR) was about 35%. This virus was considered as one of the deadliest human pathogens. In the end of 2019, novel human coronavirus was observed that is rapidly spreading across the globe. This virus has a higher degree of lethality than the endemic coronaviruses. This virus was initially named as 2019-nCoV and now has been termed as SARS-CoV-2 and causes the disease COVID-19 (Coronavirus Disease 2019).
The first case of COVID-19 was reported to the World Health Organization (WHO) by the Chinese authorities on 31st of Dec. 2019 as a result of a patient suffering with pneumonia in Wuhan, China. After that number of patients suffering from the same disease increased and by 9 January, a novel coronavirus was detected. Now within 3 months, the virus has been spread across the globe causing a huge loss. It has been observed that COVID-19 is following a closely exponential curve. Most of the cases outside China have been co-related with that of travel to that country but more clusters of cases are also detected without travel history. Italy is badly affected by the COVID-19 and its deaths numbers have crossed China deaths. It has also badly affected Spain and many other countries.
The novel virus belongs to the Coronaviridae family. Coronaviruses have large (∼30-kb) single-stranded, positive-sense RNA genomes. COVID-19 is closely related to SARS-CoV. The closest relative of SARS-CoV-2 appears to be a virus found in bats known as RaTG13-2013. SARS-CoV was transmitted to the human beings from a spillover event either directly from a bat or through an animal. Early studies on SARS-CoV-2 indicated that the spike protein utilizes ACE2 as its cell surface receptor. ACE2 is found on ciliated epithelial cells of the human lungs.COVID-19 is easily spreading in the human population within a short time. Many doctors and nurses have also been infected and more new clusters of cases are coming daily across the globe. The studies show that the virus is spreading through respiratory droplets. Both SARS-CoV and MERS-CoV also have common ancestry with viruses found in bats. Both of these viruses had an intermediate host for transmission into humans, these being palm civets and camels for SARS-CoV and MERS-CoV respectively. It is also suggested that the pangolins can be the intermediate host for SARS-CoV-2, but still this remains to be proved. There is essential to understand how SARS-CoV-2 became a human virus and how further it can be prevented. Knowing that MERS-CoV transmits to humans via dromedary camels has allowed for the development of a camel vaccine to potentially limit spread to humans. Approval for novel vaccines in animal hosts is much easier than in humans. Knowing the intermediate host helps measures to be taken to limit human contact with the animal which further can help to reduce the chances of further spread of the virus.
In case of COVID-19 outbreak, the case fatality ratio (CFR) has been found about 2% to 4%. This is a much lower CFR than SARS and MERS, which were around 10% and 35%, respectively. There is urgent need to prevent the spread of this disease and the governments across the globe are making strenuous efforts to prevent the spread this deadly virus. Governments are locking down the cities and towns and suggesting the social distancing among the people to break the chain of transmission of coronavirus. People are suggested to remain at their homes to prevent the further transmission of the virus. Health sector is leaving no stone unturned to prevent this deadly virus. Doctors and nurses are working day and night to save the lives of the patients infected with Coronavirus. Everyday new cases of COVID-19 are rising. Presently, COVID-19 has emerged as the global pandemic. It is difficult to say whether COVID-19 spread will be affected by the changing weather conditions. It is interesting to see whether the increase in temperature will affect the COVID-19. Some studies on SARS-CoV-2 determined that the cellular receptor for the virus is ACE2. This knowledge can help in the further research. Many labs around the world have started to research on this virus. New models are essential for thoroughly testing therapeutic candidates, vaccine strategies and understanding the pathology of disease. As the case count and death toll of the epidemic have continued to increase, it becomes imperative to identify therapeutic options for COVID-19.Many new interventions are under investigation to prevent this menace. Better understanding of how Coronavirus causes infection and the way in which the host responds may help direct further therapeutic avenues. Continued surveillance of viruses in animal populations is also essential to prevent the future outbreaks. Effective vaccines and therapeutic strategies are needed to treat not only this deadly virus but also such kinds of outbreaks in future. |
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