1. The term Virus was coined by Louis Pasteur and it is a Latin word which means poisonous fluid or venom.
2. Meyer in 1886 reported tobacco mosaic disease but he couldn’t isolate the casual organism.
3. First plant virus was discovered by Ivanowsky in 1892 from infected leaves of tobacco plant called as Tobacco Mosaic Virus (TMV).
4. M. W.Beijerinck (1898) demonstrated that viruses differ from other cellular organism by passing via agar gel and called the fluid as contagium vivum fluidium. He is often called the Father of Virology.
5. Towrt (1915) and Herelle (1915) reported that viruses have a tendency to even infect bacteria and they called such virus as Bacteriophage.
6. W. M Stanley (1935) crystallized TMV and reported the presence of nucleic acid not only protein in Virus and was awarded noble prize for this work in 1946.
7. Harshey and Chase (1952) reported that nucleic acids are infective and proteins are non infective in virus and discovered transformation.
8. Theodor Diener in 1971, discovered Viroids and it is a smallest infectious consist of only ssRNA and capable of self replication.
9. Stanley Prusiner reported that protein may act as infectious agent (Prions) while studying scrapie and awarded nobel Prize for this work in Physiology or Medicine in 1997.
10. Montagnier, Gallo and team in 1984 discovered AIDS virus.
11. Covid-19 is a new illness but it is caused by a coronavirus of the type first identified by Dr Almeida in 1964.
12. Safferman and Morris (1963) discovered cyanophages (virus which attack oncyanobacteria)
Viruses are obligate parasite or holoparasite, ultra microscopic, self replicating highly infectious agents that multiply only inside living host cells without involving growth and division and essentially composed of a protein covering surrounding a nucleic acid molecule (RNA or DNA).
Fundamentally differ from cellular organism in that they contain only one type of nucleic acid which may be either DNA or RNA.
Deoxyviruses (which contain DNA)
Riboviruses (which contain RNA)