MicrobeWorld

All known virus particles can be placed into one of two general categories: enveloped or non-enveloped. Viruses that fall into the former category are characterized by a lipid membrane derived from the host cell, and one or more nuclecapsid proteins that interact with the viral genome. A virus that infects an archaeal host may constitute a new category of enveloped viruses. It comprises a membrane vesicle that encloses a circular ssDNA genome which is devoid of nucleic acid-binding nucleoproteins.