Dec 3, 2025 · A virus is an infectious agent of small size and simple composition that can multiply only in living cells of animals, plants, or bacteria.

A virus consists of a core of nucleic acid surrounded by a protein coat called a capsid; some viruses also have an outer envelope composed of fatty materials and proteins.

A virus reproduces itself by taking over a living cell and making it into a virus factory. Encyclopædia Britannica, Inc.

virus, Microscopic, simple infectious agent that can multiply only in living cells of animals, plants, or bacteria.

Nov 14, 2025 · In some people the virus gets no farther, causing only a vague flulike illness to develop. The most common early symptoms of polio are mild headache, fever, sore throat, …

Oct 31, 2025 · Phages are classified in a number of virus families; some examples include Inoviridae, Microviridae, Rudiviridae, and Tectiviridae. Like all viruses, phages are simple …

A virus is an infectious agent of small size and simple composition that can multiply only in living cells of animals, plants, or bacteria.

Other articles where capsid is discussed: virus: Definition: …forms a shell (called a capsid) around the nucleic acid. Certain viruses also have other proteins internal to the capsid; some of these …

Nov 17, 2025 · Herpes simplex virus type 1 (HSV-1) is transmitted orally and is responsible for cold sores and fever blisters, typically occurring around the mouth, whereas herpes simplex …

Dec 3, 2025 · Genetic material that codes for a desired antigen is inserted into the attenuated form of a large virus, such as the vaccinia virus, which carries the foreign genes “piggyback.”