megavirus

Megavirus is a genus of giant viruses that infect amoebas. Discovered in 2010, it was initially mistaken for a bacterium due to its large size and the presence of genes typically found in cellular life. Megavirus is significantly larger than most known viruses, with a capsid diameter of about 1.2 micrometers, and its genome is over 1.2 million base pairs long, encoding for approximately 1,120 genes. This genome size is comparable to some parasitic bacteria.

The discovery of Megavirus and other giant viruses like Mimivirus and Pandoravirus has challenged the traditional definition of a virus, which are typically considered obligate intracellular parasites lacking their own metabolic machinery. Megavirus possesses genes involved in protein synthesis and DNA repair, functions usually carried out by host cells. This has led to debate about whether these giant viruses represent a fourth domain of life or are simply highly complex viruses that have acquired genes from their hosts through horizontal gene transfer.

Megavirus's lifecycle involves infecting amoeba hosts, where it replicates and eventually lyses the cell, releasing new virions. Its genetic material is double-stranded DNA. The unique characteristics of Megavirus continue to be a subject of research, providing insights into viral evolution and the diversity of microbial life.