DETERMINATION OF NUCLEOTIDE DISTRIBUTION IN THE CORONAVIRUS GENOME

The abundance and global range of bat and bird species that play the role of viruses have facilitated the widespread evolution and spread of coronaviruses. The diversity of bat coronaviruses provides ample opportunities for the emergence of new human coronaviruses. Rapid mutation and genetic recombination also contribute to the evolution of human coronaviruses. The acquisition or loss new protein-encoding genes has the potential to dramatically alter viral phenotypes. Among SARS-CoV proteins, ORF8 is thought to play a key role in adaptation to humans, as bat viruses related to SARS-CoV have been isolated and found to encode distinct ORF8 proteins. At the beginning of the human epidemic, 29 nucleo- tide deletion features characteristic of SARS-CoVs were found in the isolated strains. This deletion splits ORF8-1 into ORF8a and ORF8b and is thought to be an adaptive mutation that allows host-to-host transmission. Comparing SARS-CoV-2 with six other HCOVs reveals interesting similarities and differ- rences. First, the incubation period and duration of HCOV disease are very similar. It is being inves- tigated whether the transmissibility of SARS-CoV-2 decreases after passing through humans, as in the case of SARS-CoV and MERS-CoV. The lack of repair in these viruses leads to the accumulation of mutations in the virus genome and the increase of mutability in newly formed virus strains. Also, new forms arise as a result of the host orqanism avoiding the pressures of the immune system. As a result of our research, we determined the distribution of nucleotides in the coronavirus genomes, and it turned out that the concentrations in different viruses are close. Nucleotide concentrations are distrubited in chromo- somes and genes with a certain regularity. Mutations that occur in a specific area in the viral genome affect the concentration in the total nucleotide sequence, which, if they occur in one fragment, is distri- buted in other fragments, which leads to a constant concentration in the common genome. Investigation of similarities and differences in the genome composition of viruses, the study of the mechanism of infection of the host cell, can play an important role in the development of vaccines against them. The information obtained from studies of the viral genome can be used to prevent the use of viruses as biological weapons.