Discovery of Virus
In 1884, Charles Chamberland found out that the agent responsible for rabies passes through the porcelain filter.
In 1892, Ivanowski discovered that the agent responsible for Tobacco mosaic disease does not pass through the filter and bacteria free filtrate still caused the disease.
After that, it was discovered that filtrate caused many diseases.
- In 1935, Stanley purified filterable agents and was successful in crystallizing tobacco mosaic virus and found out that they contained only proteins and nucleic acid.
- This led to the discovery of viruses.
Structure of Virus
Virion
Infectious part consists of the genome and capsid.
Genome
Nucleic acid. either DNA or RNA. Forms central core
Capsid
Protein coat. made of protein subunits called capsomeres. Adenovirus has 252 capsomeres while heroes virus has 162 capsomeres.
Envelop
Sometimes. the nucleocapsid is covered bv another membrane derived from the host cell. called envelope.
Virus is non-living outside the body of the host but once it enters the host body it starts reproducing using the host machinery.
