wirusem

Wirusem is the instrumental singular form of the Polish noun wirus, meaning a virus. It is used in phrases such as zostałem zainfekowany wirusem to denote the infectious agent involved. It is not a distinct scientific term, but a grammatical form of the word virus in Polish.

In biology, a virus is a submicroscopic infectious agent that can replicate only inside living cells. Viruses are primarily composed of genetic material—DNA or RNA—enclosed in a protective protein coat called a capsid; some also have a lipid envelope derived from the host cell membrane. Their genomes encode a limited number of proteins, and they rely entirely on host cell machinery to reproduce.

Viral life cycles begin with attachment to a susceptible cell, entry and uncoating of the genome, transcription and replication of genetic material, synthesis of viral proteins, assembly of new virions, and release by budding or cell lysis. Because they need a host, viruses are described as obligate intracellular parasites. They infect all domains of life, from bacteria (bacteriophages) to plants and animals, including humans.

Viruses vary in size, shape, and genome organization. They can have DNA or RNA genomes, single- or double-stranded, and can evolve rapidly through mutation and recombination. Transmission routes are diverse: respiratory droplets, direct contact, bodily fluids, contaminated food or water, vectors such as mosquitoes, and occasionally inherited viral sequences in the germline.

Impact and response: viruses cause a range of diseases, from mild colds to severe illnesses. Public health responses include vaccination, antiviral drugs, hygiene measures, and surveillance. Research on viruses has provided insights into molecular biology, gene expression, and immune defense.