In the past few weeks, we have all learned a lot about COVID-19 disease and the SARS-CoV-2 virus that caused it. While the number of scientific articles on this virus, which caused a global crisis, has increased, there are still many gray areas regarding its origins. In which animal species did it occur? A bat, pangolin, or other wild animal species? Where does it come from? Is it from a cave in Hubei province of China or from the forest? Or none? There are a number of questions that the scientific world must answer. In December 2019, 27 of the first 41 people hospitalized (66 percent) visited a seafood market located in the heart of the city of Wuhan in Hubei province, but the first case detected, according to a study by Wuhan Hospital, never went to this market. As part of a study published last month, Chinese scientists analyzed the genome of 70 virus samples from China and elsewhere between 24 December 2019 and 3 February 2020 to investigate the evolutionary history of the new type of coronavirus. Comparative genomic analysis showed that SARS-CoV-2 belongs to the Betacoronavirus group and is very similar to SARS-CoV, which originated in November 2002 in Guangdong province of China and spread to 29 different countries. The virus, which caused severe acute respiratory illness in people who were infected, caused 774 out of 8,098 infected people to die. In the research conducted at that time, it was determined that Rhinolophus bats were the reservoirs of this virus and that the palm musk cat served as an intermediate host between bats and early cases. The nucleic acid called RaTG13, which was recently collected from the laws of the Rhinolophus affinis species in the Greek city of China, turned out to be 96 percent similar to SARS CoV-2. The World Health Organization (WHO) considers bats as the most likely natural reservoir of SARS-CoV-2, but the differences between bat coronavirus and SARS-CoV-2 suggest that humans are infected by an intermediate host. At this point, pangolin comes into play. In a study published on February 7, 2020, we learned that the genomic compatibility of pangolin is 99 percent similar to SARS-CoV-2. This indicates that the animal in question may have served as an intermediate reservoir in the transmission of the virus to humans. In addition, these genomic comparisons show that the SARS-Cov-2 virus is a result of recombination between two different viruses, one closer to RaTG13 and the other to the pangolin virus. In other words, the new type of coronavirus can be a chimera between two pre-existing viruses. In order for recombination to occur, two divergent viruses must infect the same organism at the same time. So, in what organism did this recombination occur? A bat, a pangolin or some other kind? And above all, under what conditions did this recombination occur? The scientific world hopes to find answers to these questions with new studies.
