ABSTRACT
Virolgy, as the name suggests, is the study of viruses. Viruses are intracellular, obligate parasites that require a host cell to multiply. They can infect all forms of life, such as bacteria, plants, mammals, fungi, and many more. They neither fossilize nor do they have a common ancestor. Viruses were initially identified as a microorganism that could kill bacteria, but not a bacteriophage because of its extremely small size. A virus has different attributes that decide the complexity of the infection caused. First, the viral genome could be either RNA (ribonucleic acid) or DNA (deoxyribonucleic acid). Again, this RNA or DNA could be either single stranded (positive or negative sense) or double stranded. The viral infection cycle could cause cell damage or death. However, since the virus depends on the host cell survival for its own replication, sometimes the virus maintains mild infections until it encounters environmental stress, with some exceptions such as HIV, Ebola, and few more. Therefore, to determine the pathogenicity of a virus, many factors need to be taken into consideration that include viral genome, potential host, and its immune system (including virus-host interaction) and the type of infection.
