How were viruses discovered?
Back in the 19th century, scientists were unable to identify the causative agent (the causing factor) for rabies. Microbiologists studied the case and even developed a filter that would separate bacteria from a solution, thinking that bacteria was the causative agent.
Louis Pasteur (Left) and Charles Chamberland (Right), the two french microbiologists who hypothesised that there was a pathogen smaller than bacteria.
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However, Russian microbiologist, Dmitri Ivanovsky conducted an experiment on infected leaves using the filter. He eventually discovered that bacteria were not the agent (as the leaf remained infected), but a smaller pathogen existed, now known as viruses.
Upon discovery, Ivanovsky named the pathogen, "Contagium Vivum Fluidum". Soon after its discovery, a dutch microbiologist, Martinez Beijerinck named the pathogen "Virus", as an allusion to the latin word for "poison".
What kind of viruses are there?
With thousands of different viruses discovered, mankind has given them classifications in order to organise and simplify the different types of viruses.
The classifications begin with whether the virus contains a DNA or an RNA type nucleic acid. This classification affects the process of the infection on the host. Take a look at "INFECTION".
Further classification divides the different viruses into individual families. The specific classifications of both DNA and RNA type viruses can be seen from the diagram underneath.
As seen from the diagram, different types of viruses come with different structures. Below are some of the most common structures of viruses.
