range from familiar viruses that can infect humans and other vertebrates, such as those of the Poxviridae and Asfarviridae (the cause of African swine fever) families, respectively, to poorly understood viruses that seem to primarily infect insects, Paramecium, algae, or, as in the case of Marseilleviridae, amoebae. These viruses are unique both in size and genetic makeup, frequently including genes of a variety of viral, bacterial, and cellular origins, including protists. It has recently been proposed that the giant