vírust

Vírust is a term used to describe viruses in a broad sense. Viruses are small infectious agents that cannot reproduce on their own and must infect a living cell to replicate. They are composed of genetic material, either DNA or RNA, enclosed in a protein shell called a capsid; some also carry a lipid envelope derived from a host cell membrane. Outside a host, virust particles are inert and lack independent metabolism.

Replication begins when the virust attaches to specific receptors on a susceptible cell, enters the cell, and releases its genome. The virus then uses the host’s machinery to synthesize viral components, assembles new virust particles, and releases them to infect additional cells. Replication strategies vary and can include cytopathic effects, integration into the host genome, or budding from the cell surface without immediate destruction of the cell.

Classification of virusts is based on genome type (DNA or RNA, single- or double-stranded, positive- or negative-sense), presence or absence of an envelope, and structural features. The Baltimore classification and the taxonomy developed by the International Committee on Taxonomy of Viruses (ICTV) provide widely used frameworks. Virusts infect all domains of life and exhibit a broad range of host specificities, from broad to highly restricted.

Transmission routes include airborne spread, direct contact, indirect contact via contaminated surfaces, vector-borne transmission, and, in some cases, fecal-oral routes. Disease outcomes range from mild to severe, influenced by viral properties and host responses. Diagnostics commonly use molecular methods (such as PCR), antigen detection, and serology, often complemented by genome sequencing for surveillance. Prevention and treatment involve vaccines, antiviral medications, and public health measures to reduce transmission and manage outbreaks.