Viral Pathogens

Viral pathogens are viruses that cause disease in their hosts. Viruses are microscopic, obligate intracellular parasites that lack their own metabolic machinery and must hijack the molecular machinery of host cells to replicate. They consist of a core of genetic material—either DNA or RNA—enclosed within a protein coat called a capsid. Some viruses also have an outer lipid envelope derived from the host cell membrane. Viral pathogens cause a wide spectrum of diseases ranging from mild illnesses like colds to severe conditions such as AIDS, hepatitis, influenza, COVID-19, polio, measles, smallpox, dengue fever—and some can lead to cancer. Their ability to cause disease stems from both direct effects on infected tissues and indirect consequences mediated by immune responses.

Varies depending on the specific antiviral drug; examples include inhibition of viral replication enzymes, blocking viral entry, and enhancing host immune response.