virusai

Virusai refer to viruses in some languages and, more broadly, to viruses as a group of infectious agents. They are submicroscopic and composed of genetic material—DNA or RNA—encased in a protein coat called a capsid, and sometimes surrounded by a lipid envelope. Virusai are obligate intracellular parasites: they cannot carry out metabolism or replicate outside a living host cell and must hijack host cellular machinery to reproduce.

Virusai vary in size and structure, but share key features. The genome can be double-stranded DNA, single-stranded DNA, double-stranded RNA, or single-stranded RNA, with positive or negative sense. The viral life cycle typically begins with attachment to a specific receptor on a host cell, entry, genome replication, production of viral proteins, assembly of new virions, and release by cell lysis or budding. Some virusai integrate their genome into the host genome and can remain dormant for periods.

Virusai are classified in multiple families and orders, commonly grouped by Baltimore classifications. They can infect all life forms, including bacteria, plants, and animals. In humans, infections can cause illnesses ranging from mild to severe. Public health responses include vaccination, antiviral medicines, and infection prevention measures. In research and medicine, virusai serve as tools for gene delivery and biotechnology, with viral vectors used in gene therapy and vaccines.