 Hello and welcome to Physiology Open. With COVID-19 being declared a pandemic, it is essential that we stay at home and fight coronavirus by social distancing. But all present and fast events give us an opportunity to be prepared for the future. So in this video we will see how this novel coronavirus was identified. A 41-year-old patient who worked at a local seafood market presented with severe respiratory syndrome symptoms of fever, dizziness, unproductive cough and chest tightness and was admitted to Wuhan Central Hospital. The patient's arterial blood gas analysis revealed the presence of decreased partial pressure of oxygen that is hypoxemia and chest radiographs with ground loss capacities in aerospace and scinti scan were indicative of pneumonia. After that, the patient was screened for various pathogens which could cause this clinical picture like bacterias, chlamydia pneumonia, mycobacterium pneumonia and viruses like influenza and adenovirus etc. using respective tests for identification. But the physicians could not find the cause so they started empirical treatment to combat bacteria, virus and inflammation altogether by giving the patient the combination of antibiotics, antividols and anti-inflammatory ducts. However the condition of the patient did not improve and he was transferred to ICU. After that physicians collected a sample from alveoli by a method known as bronchoalveolar lavage. In this method a bronchoscope is passed through mouth or nose into the lungs and a small amount of normal salin is instilled and then the sample is sucked back. So whatever cells microbes are present in the alveoli are collected in the sample. After this they extracted total RNA from this sample. Okay, we will digress a little bit here. Our genetic material that is DNA or RNA is made up of nucleotides and the sequence in which these nucleotides are arranged differs in different species. The sequence in which the nucleotides are arranged is known as genome sequence. The genome sequence of various organisms are stored in libraries. So in this case the aim was to determine the genome sequence of the organism and match it to known genome sequences which are maintained in a library so that they can identify the organism. The genome has nucleotide sequences known as genes. Genes we can say are functional representation of genomes. So a group of nucleotide sequences which functions as a unit is known as a gene. Some of these nucleotide sequences that is genes can be transcribed into mRNA and then translated into proteins while some genes cannot be transcribed. Based on this there are two ways in which gene libraries are maintained. There is one genomic library where complete genome is cut into small fragments and stored that is it includes genes which can be transcribed as well as that cannot be transcribed. Second way of maintaining these gene libraries is as complementary DNA library that is cDNA library. Now in this cDNA library only the genes which can be transcribed are stored. See genes are transcribed into mRNA which is then translated into proteins. So to maintain cDNA libraries mRNA of an organism is extracted. We know the genes which are not transcribed cannot have mRNA right. So mRNA is extracted converted into its complementary DNA and stored as fragments. So it will represent the genes which can be transcribed only. This can be done since matching of base pairs in the DNA is very specific. You know there is a nucleotide rule right adenine pairs with thymine and cytosine pairs with guenine. In RNA there is a difference adenine pairs with uracil instead of thymine. So you take a sample of RNA add the enzyme known as reverse transcriptase because you want to reverse the process of transcription and convert this RNA into DNA and also add some nucleotides which are present in DNA automatically the nucleotide which pairs with the nucleotide in RNA will come to its place and then RNA is removed and on the similar lines another strand of DNA is synthesized. It is important to do so because libraries are maintained as DNA. So to determine the genome sequence of the organism what they did that they extracted RNA from the sample of bronchoalvululavate and then converted it to its complementary DNA through which they obtained lots of fragments of cDNA. Then they sequence their ends that is identify the nucleotides present at these fragments of cDNA by using some probes of matching nucleotides. This is all possible because of the nucleotide rule right. After this is done there are algorithms which can arrange the short fragments of cDNA into representation of original chromosome. It itself is a very complex topic how that assembly of short segments of cDNA is made into a complete genome. So that is not the subject of this video. Anyways now the assembly DNA is compared with known libraries to see the similarities between obtained DNA and already known DNA. So what they found after the comparison was that such genome did not exist. Rather it had much similarity to that of human SARS coronavirus, severe refute respiratory syndrome coronavirus and with a bat coronavirus. So that's how we know about the novel coronavirus and its genome. It was initially named as WHCD that is Wuhan Human One Coronavirus but now International Committee on Taxonomy of Viruses has named the virus as SARS-CoV-2 that is severe acute respiratory syndrome coronavirus 2 and the disease which it causes as COVID-19. Okay thank you for watching the video. Hopefully this video helped you in enhancing your knowledge about coronavirus. Thank you.