Viruses are tiny infectious agents which can contaminate plants, animals, insects and even microscopic organisms. An extensive variety of infections are portrayed by their size and their protection from synthetic or physical agents and pathogenic effects. Now-a days, they concentrated on two things; Viruses are dependent on host cell machinery for their replication and both bacterial and animal viruses are responsible for bringing about a recombinant DNA revolution. Because of these reasons, viruses are centered around their utilization in cell and sub-atomic science as they can answer many arising questions in biology. Viruses show solid immunological reactions with both cell and humoral immunity. Many antivirals were created to treat viral diseases by targeting viral replication stages.