How Viruses Work: Virology

Components of genomes

Mainly the viruses are comprised of nucleic acids (genome), proteins (capsid), and lipids (envelope). The capsid is a protein covering that encompasses and protects the viral genome. It is comprised of numerous small subunits called capsomeres which determine the shape of the virus. Envelopes are the lipid bilayer membranes that are derived from the host cell membrane when virus “buds” out from the plasma membrane or passes through a membrane-bound organelle (For example the Golgi body or endoplasmic reticulum). The envelope contains sometimes glycoprotein (protein with starch) as spikes which helps them in the attachment during the time of infection to the host cell surface. In non-enveloped viruses, Crimps present in the capsid and specific capsid proteins may attach to the cell surface receptor.

The most significant and trademark feature of a living organism is the replication of its genetic data. The mechanism of genome replication is finished with a more prominent economy and simplicity among various viruses. Different families of viruses have their genome including either double-stranded (ds) DNA or single stranded (ss) DNA or RNA. The viruses that contain RNA genome can either positive, negative, or mixed polarity. Also, they either have single or multiple segments in their genome with linear or circular topology. Every one of the above parameters has its issues for the pathways of viral genome replication, viral gene expression, and virion assembly. In between the families of viruses that infect animals and humans, those containing RNA genome as well as DNA genome. This difference is much more in the case of plant viruses.