After direct contact and entry into the host cell, the virus particle loses its shell or gets uncoated, and its genome enters the host cell cytoplasm. The reader may already be familiar with RNA which is Ribonucleic Acid, and it has one strand and shorter compared to DNA that has two strands. The coronavirus RNA genome has a 5 methylated cap and a 3 polyadenylated tail, which allows the RNA to attach to the host cell’s ribosome for translation.

Coronavirus genomes also encode a protein called RNA-dependent RNA polymerase (RdRp), which allows the viral genome to be transcribed into new RNA copies using the host cell’s machinery. The RdRp is the first protein to be made; once the gene encoding the RdRp is translated, translation is stopped by a stop codon. This is known as a nested transcript. When the mRNA transcript only encodes one gene, it is monocistronic. Coronavirus non-structural proteins provide extra fidelity to replication, because they confer a proofreading function, which is lacking in RNA-dependent RNA polymerase enzymes alone. The genome is replicated and a long polyprotein is formed, where all of the proteins are attached. Coronaviruses have a non-structural protein, which is able to cleave the polyprotein. This process is a form of genetic economy, allowing the virus to encode the greatest number of genes in a small number of nucleotides.

The reported illnesses of Coronavirus COVID-19  range from mild symptoms to severe illness and death. Symptoms can include fever, cough and shortness of breath. Those symptoms may appear in as few as 2 days or as long as 14 days after exposure. This information is based on what has been already known as the incubation period of MERS-CoV viruses.