One of a group of minute (15–300 nm) infectious agents characterized by a lack of independent metabolism and the ability to replicate only within living cells.
Submicroscopic organism that causes infectious disease. In cancer therapy, some viruses may be made into vaccines that help the body build an immune response to, and kill, tumor cells.
A simple, noncellular particle (entity) that can reproduce only inside living cells (of other organisms). The simple structure of viruses is their most important characteristic. Most viruses consist only of a genetic material either DNA (deoxyribonucleic acid) or RNA (ribonucleic acid) and a protein coating. This (combination) material is categorized as a nucleoprotein.
Some viruses also have membranous envelopes (coatings). Viruses are “alive” in that they can reproduce themselves although only by taking over a cell’s “synthetic genetic machinery”—but they have none of the other characteristic of living organisms. Viruses cause a large variety of significant diseases in plants and animals, including humans. They present a philosophical problem to those who would speak of living and nonliving systems because in and of itself a virus is not “alive” as we know life, but rather represents “life potential” or “symbiotic life.”
Infectious complex of macromolecules that contain their genetic information either as DNA or RNA; viruses need host cells for replication and the formation of new viral particles.
A disease in plants which is incurable and may be fatal. However, some viruses are relatively benign, such as the one that makes tulips “break” into stripes.
A chemical substance that has characteristics of a living organism.
A parasite consisting of a nucleic acid surrounded by a protein coat that can only develop in other cells. Viruses cause many diseases including the common cold, AIDS, herpes and polio.
The infective agents of a wide range of plant diseases, which as in human viral diseases, cannot be eliminated by any chemical agent and are thus incurable. They may be fatal or very debilitating to the plants and some viral diseases are much feared by commercial growers. However, some viruses are relatively benign, such as the one that makes tulips ‘break’ into stripes.
An infective agent capable of growth and reproduction only in living cells.
Microbe that uses the body’s own cells to make copies of itself.
Small particle that is not living, does not exhibit signs of life, but can reproduce itself within a living cell. A virus particle is called a virion; it consists of a nucleic acid (DNA or RNA) core and a protein coat, called a capsid. A virus reproduces by infecting a host cell and taking over the nucleic acid of that host cell, making more virus nucleic acid and protein. As new virus particles develop, the host cell bursts, releasing die new virus particles. Viruses are responsible for many human diseases.
A tiny particle of protein and nucleic acid that is able to pass into living cells and cause changes in the chemistry of the cell. Many viruses are capable of causing disease.
A minute particle that is capable of replication but only within living cells. Viruses are too small to be visible with a light microscope and too small to be trapped by filters. They infect animals, plants, and microorganisms. Each consists of a core of nucleic acid (DNA or RNA) surrounded by a protein shell. Some bear an outer lipid capsule. Viruses cause many diseases, including the common cold, influenza, measles, mumps, chickenpox, herpes, smallpox, polio, and rabies. Antibodies are ineffective against them, but many viral diseases are controlled by means of vaccines.
The term applied to a group of infective agents which are so small that they are able to pass through the pores of collodion filters. They are responsible for some of the most devastating diseases affecting humans: for example, influenza, poliomyelitis, smallpox and yellow fever. The virus of influenza measures 80 nanometres, whereas the staphylococcus measures 1,000 nanometres (1 nanometre =one thousand-millionth of a metre).
A pathogen composed of nucleic acid within a protein shell, which can grow and reproduce only after infecting a host cell. More than 400 types of viruses that cause a great variety of illness are known. All of them can attach to cell membranes, enter the cytoplasm, take over cellular functions, reproduce their parts, and assemble themselves into mature forms capable of infecting other cells.
A tiny disease-causing particle that consists of genetic material and a protein coat.
Smallest of all disease-causing pathogens.
A parasitic submicroscopic particle that infects and resides in cells of biological organisms. A virus is capable of replication only through taking over the host cell’s reproductive function.
A nucleoprotein substance possessing the capability to traverse filters that retain bacteria and reproduce within the living cells of a host organism.
A minute and pathogenic entity, capable of replicating solely within living cells, is responsible for a diverse range of infectious diseases.
One of a collection of disease-causing microorganisms that are smaller than the commonly recognized bacterial forms.
A member of a group of microorganisms that cause disease and are smaller than conventional bacteria.