ERVW-1 and infection: Similarly, it has been shown that alphaviruses acquire host-specific alterations that improve their ability to establish infection in the new host; these host-specific differences range from differential packaging of host components such as 18S rRNAs that improve the viral infectivity on mammalian cells to glycosylation of the envelope glycoproteins, which allows for targeted infection of certain mammalian cell types [2,3,4,5,6].