Microbiology Virology

Flashcards on Virology

Virology

The scientific discipline concerned with the study of the biology of viruses and viral diseases, including the distribution, biochemistry, physiology, molecular biology, ecology, evolution and clinical aspects of viruses.

Virus

From a Latin word meaning slimy liquid or poison; a small infectious agent that replicates only inside the living cells of an organism.

Virology

Experiments on this began with the experiments of Edward Jenner in 1798.

Edward Jenner

He inoculated a 13-year-old boy with vaccinia virus (cowpox), and demonstrated immunity to smallpox.

WHO

Announced on May 8, 1980, that the world was free of smallpox.

Janet Parker

In the summer of 1978, the last known case of smallpox was reported, claiming the life of 40-year-old medical photographer.

Louis Pasteur

In 1881-1885 he first used animals as model for growing and studying viruses; he found that the rabies virus could be cultured in rabbit brains and discovered the rabies vaccine.

Adolf Mayer

Observed the dark and light spot on infected leaves of tobacco plant and named it tobacco mosaic disease.

Dimitri Ivanovsky

Demonstrated that sap of the leaves infected with tobacco mosaic disease retains its infectious property even after its filtration through a Chamberland filter.

Martinus Beijerinck

Independently replicated Ivanovsky's experiments and became convinced that the filtered solution contained a new form of infectious agent, which he named virus; he surmised that the virus under a study was a new kind of infectious agent, which he designated contagium vivum fluidum.

Friedrich Loeffler and Paul Frosch

Discovered an animal virus that causes foot-and-mouth disease in cattle (1898).

Walter Reed and his team

Discovered the yellow fever virus, the first human virus from Cuba in 1901.

Poliovirus

Discovered by Karl Landsteiner and Erwin Popper in 1909.

Adsorption

A recognition process between a virus and the host cell that results in virus attachment to the external surface of the host cell.

Penetration

Entrance of the virion (either a whole virus or just its nucleic acid) into the host cell.

Replication

Copying and expression of the viral genome at the expense of the host's synthetic equipment, resulting in the production of the various components.

Assembly and maturation

Of these individual viral parts into whole, intact virions.

Release

Escape from the host cell of an active, infectious viral particles.

Eclipse

The early stages of viral replication, a period during which no mature virions can be detected within the host cell.

Lytic infection

An active, infectious stage. Example: Influenza (flu virus)

Lysogenic infection

A dormant (sleeping) stage - period between an infection and the onset of disease. Example: Human Immunodeficiency Virus

Lysogeny

Condition in which the host chromosome carries bacteriophage DNA.

Transduction

Is the process by which foreign DNA is introduced into a cell by a virus or viral vector. An example is the viral transfer of DNA from one bacterium to another.

Adsorption (attachment)

Begins when the virus encounters a susceptible host cell and adsorb specifically to receptor sites on the cell membrane.

Penetration of animal viruses

Unlike bacteriophage, animal viruses have no mechanism to inject their nucleic acids. Instead, the flexible cell membrane of the host is penetrated by the whole virus or its nucleic acid.

Uncoating

When enzymes in the vacuole dissolve the envelope and capsid, the virus is said to be this. The viral nucleic acid escapes from the capsid.

Biosynthesis

Viral genes are expressed, resulting in the production of pieces or parts of viruses (i.e., viral DNA and viral proteins)

Assembly

The viral pieces or parts are assembled to create complete virions.

Release

The complete virions escape from the host cell by lysis or budding (or exocytosis).

Prions

The normal form of the protein is called Prpc, while the infectious form is called Prps the C refers to 'cellular' PrP, while the Sc refers to 'scrapie', the animal prototypic prion disease, occurring in sheep.