Introduction of virus into the cell, replication and transcription
The replication of coronaviruses occurs in host cell cytoplasm. The virus primarily bind to the receptor on the cell surface via the spike (S) protein. When S protein is bound to the receptor, a conformational structure occurs in the structure and the process of entry into the virus cell begins. This process with endocytosis is dependant of pH through the receptor. After entering the cytoplasm, the virus particle release the RNA genome. This genome is a single-stranded, non-segmented RNA virus with the largest known RNA genome (gRNA), which is approximately 26-32kb. The genome consist of seven genes. It is organized into 5′ non-structural protein coding regions comprising the replicase genes (gene 1), which are two-thirds of the genome, and 3′ structural and nonessential accessory protein coding regions comprising the gene 2-7.