Describe homologies between virophage genomes and that of their host viruses

Hi Connorp,

Best way to approach this question is to look at actual examples where this occurs in nature. For example, the Sputnik virophage is a satellite virus of the giant mimivirus. Therefore, it would be best to research similarities in the genome of the Sputnik virophage and the giant mimivirus. Without further research, I would assume that there aren't much similarities. The reason why Sputnik "preys" on the mimivirus is because it's able to latch onto the mimivirus' capsid and inject its genome. A similar analogy would be the hepatitis B virus infecting human hepatocytes. They share nothing in common. Other general similarities that are not worth mentioning would be the production of capsid protein.

I read somewhere about lateral gene transfer occurring, but wasn't sure.

While you're here, I guess I'll also ask why satellites can only latch on the their specific host. Like what makes mamavirus unique in that Sputnik can infect it and only it?

I'd assume that virophages would latch on similarly to how bacteriophages latch onto bacteria, given that the virophage infects amoeba. Also, given the small size of these entities, I wonder how they are even studied! Only one who has worked in a lab could really appreciate this. According to a Wikipedia article, the Sputnik virophage has icosahedral symmetry and within each asymmetric unit of the structure, there are 4 and 1/3 hexon capsomers. On the 3-fold axis lies one hexon which gives rise to the 1/3 hexon in each asymmetric unit. There are flexible, mushroom-like fibers that protrude from each hexamer. Each asymmetric unit also houses 1/5 of a penton which lies on each 5-fold axis. In the middle of the pentamers are cavities that may allow for the entry or exit of DNA. Sputnik has a triangulation number of 27 with 260 hexamers and 12 pentamers. This virus has 13 major capsid proteins and has recently been discovered to be non-enveloped which goes against what has been previously reported.