animavirus

WHAT IS A VIRUS? Viruses may be defined as acellular organisms whose genomes consist of nucleic acid, and which obligately replicate inside host cells using host metabolic machinery to different extents, to form a pool of components which assemble into particles called virions. F Viruses cannot be grown on sterile media, but require the presence of specific host cells. F A virus differs from a cell in three fundamental ways: i A virus usually has only a single type of nucleic acid serving as its genetic material. This can be single or double stranded DNA or RNA; ii Viruses contain no enzymes of energy metabolism, thus cannot make ATP; iii Viruses do not encode sufficient enzymatic machinery to synthesize their component macromolecules, specifically, no protein synthesis machinery.
Mouse primary spleen cells transduced with a GFP (green fluorescent protein)-retrovirus vector
WHERE WE STAND IN 2001: PREVENTING • CONTROLING • CURING VIRAL DISEASES
FourCorners Virus (Hanta)
THE DISCIPLINE OF VIROLOGY The study of virology inherently involves a merging together of what has traditionally been thought of as two separate "kinds" of science: basic and applied science. We want to figure out how viruses are transmitted, how they replicate, and how the host organism responds. We also want to figure out how to prevent transmission, how to interfere with virus replicaton, and how to confer immunity on the host. The "applied" follows from, and is dependent upon, the "basic" in a quite direct way. Virology as it is studied today, is therefore an outgrowth of both: Infectious diseases - because of the recognition of viral pathogens. Molecular Biology- because of the usefulness of viruses as probes of cell and molecular biology and metabolism, and as vectors with strong potential for gene therapy.
Viral diseases have played a major role in human history over whatever time scale we choose to explore:
Over the past 1000 years: Smallpox and measles were brought to North and South America by early European explorers/conquerers. These diseases, for which the native American populations had no acquired partial immunity, killed of A the populations, Over thelarge past fractions 100 years: newly emergedand were a major factor in the decimation of these societies. strain of influenza killed 20 million people in 1918-1919 in the immediate aftermath of World War I. A decade later, polio became one of the most feared infections of children and young adults (including Franklin D. Roosevelt, the U.S. President throughout the Depression and World Warentered II). As the century its final 20 years, a new ~100% lethal virus, HIV, spread rapidly around the world via body fluid transmission.
Viruses are distinguished from other obligate parasites, some of which are even simpler than viruses:
MYCOPLASMA: Small bacterium that grows only in complex medium or attached to eucaryotic cells.
PRION (proteinacious infectious agent): Hypothesized identity of the unconventional slow viruses (such as the Kuru, Scrapie and “Mad cow” disease agents). No nucleic acid is known to be required for prion function. They are thought by many to consist solely of protein and perhaps lipids. Study of these agents has resulted in 2 nobel prize awards.
F How long viruses have been within our midst? 1500 BC: Leg deformities indicative of poliomyelitis, pock marks indicative of smallpox and.
"Virus" is from the Greek meaning for "poison" and was initially described by Edward Jenner in 1798. During the 1800's, all infectious agents were considered to be viruses until Koch developed pure culture techniques which allowed the separation and growth of bacteria. In the late 1800's: Bacteria were purified and established as disease causing agents. It then became possible to distinguish them from the "filterable agents", those able to pass through special filters designed to prevent the passage of bacteria. The first viruses described were foot and mouth disease (a picornavirus), 1898, Yellow fever (a flavivirus), 1900, Rous sarcoma virus (an oncogenic retrovirus),
Over the past 10 years: As the global HIV epidemic continues, sporadic cases and outbreaks in humans of some non-human host viruses such as Ebola and Hanta raise the concern about future epidemics by other viruses in the new century.