nonenveloped

Nonenveloped refers to organisms or particles that lack a surrounding lipid envelope. In virology, the term applies to viruses whose nucleocapsid is not encased in a host-derived lipid membrane. These viruses have a protein capsid that encases their genetic material and may present surface proteins or spikes, but there is no external lipid bilayer.

This structural difference influences stability and transmission. Nonenveloped viruses tend to be more resistant to environmental stresses such as desiccation, heat, and common detergents, contributing to their persistence on surfaces and in the gastrointestinal tract. Because they lack a lipid envelope, they are often more resilient outside a host than enveloped viruses, though stability varies by virus. This has implications for disinfection and infection control; disinfectants that disrupt lipid membranes are less effective against nonenveloped viruses, while oxidizing agents such as bleach, hydrogen peroxide, or peracetic acid can inactivate them.

Most nonenveloped viruses follow different entry mechanisms; they typically attach to host receptors via capsid proteins and enter through endocytosis or direct penetration, with uncoating occurring in the cytoplasm or endosome.

Common human representatives include adenoviruses, rhinoviruses, poliovirus and other enteroviruses, noroviruses, caliciviruses, parvoviruses, and reoviruses. The classification into enveloped and nonenveloped viruses is a fundamental distinction in virology, informing expectations about environmental stability, transmission, and appropriate disinfection strategies.