Discovery of Viruses

Microbiology & Virology 1892

Discoverers: Dmitri Ivanovsky, Martinus Beijerinck

Overview

Demonstration that tobacco mosaic disease is caused by an agent smaller than any known bacterium, passing through porcelain filters — the first evidence of viruses.

Significance

Revealed an entirely new category of pathogen, eventually leading to understanding of viral diseases from influenza to HIV/AIDS.

Methodology

Filtration of infected tobacco leaf extract through Chamberland filters, showing the filtrate remained infectious despite excluding all known bacteria.

Impact