What are viruses???cold sores the flu measles AIDSvirus•nonliving particle•strand of hereditary material surrounded by a proteincoating•no nucleus or other organelles•no cell membrane•can have many shapes•too small to be seen with the light microscope
how do viruses multiply•all viruses can make copies of themselves•they can’t do that without the help of a living cell•the living cell is called a host cell•crystallized viruses can be stored for years. Then, ifthey enter an organism, they can multiply quickly.•once a virus is in a host cell, the virus can act in 1 of 2ways: •be active •become latent (inactive)
active virusesWhen a virus enters a cell and is active, it causes the host cell tomake new viruses. This process destroys the host cell.Steps that occur: virus aaches to a specific host cell virus’s hereditary material enters the host cell hereditary material causes the cell to make viral hereditary material and proteins new viruses form inside the host cell new viruses are released as host cell bursts open and is destroyed
latent virusesvirus enters the cellits hereditary material can become part of the cell’s hereditarymaterialdoes not immediately make new viruses or destroy the cellas host cell reproduces, the viral DNA is copiedcan be latent for yearscertain conditions, whether inside or outside your body, causethe latent virus to become an active virus
example: COLD SORE a latent virus in the body has become active cold sore is a sign that the virus is active and destroying cells in your lip when the cold sore goes away, the virus has become latent again virus is still in your body’s cells, but it is “hiding” and doing no apparent harm
how do viruses affect organisms?Who can viruses aack? animals, plants, fungi, protists, bacteriaSome viruses only infect only specific kinds of cells... Some viruses are limited to one host species (ie: potato leafroll virus) or to one type of tissue. Some can aﬀect a broad range of hosts. Rabies, for example, can infect humans and many animals.The virus and the place it aaches to the surface on the hostcell must fit together exactly. Because of this, they usuallyonly aack one type of cell.
How do viruses move?They cannot move by themselves. They reach a host’sbody by being carried by the wind or by being inhaled.
ﬁghtingvirusesWe fight viruses by geing VACCINESthey are used to prevent diseasesmade form weakened virus particles that can’t causedisease anymorevaccines have been used to prevent many diseases, such as:measles, mumps, smallpox, chicken pox, polio, rabies, swineflu
first vaccine Edward Jenner is credited with developing the first vaccine in 1796. He developed a vaccine for smallpox, a disease that was still feared in the early twentieth century. Jenner noticed that people who got a disease called cowpox didn’t get smallpox. Jenner didn’t know he was fighting a virus
treating viral diseasesWHAT YOUR BODY DOES ON ITS OWN: make interferons.What are interferons??? proteins that are produced rapidly by virus-infected cells they move to non-infected cells, causing them to produce protective substances.MEDICINE THAT CAN HELP: Antiviral drugsAntiviral drugs can be given to infected patients to help fight avirus.Some are eﬀective, but some have adverse side eﬀects.Antibiotics treat bacterial infections but not viral diseases
preventing viral diseasesPublic health measures for preventing viral diseasesincludes: Vaccinating people Improving sanitary conditions Quarantining patients Controlling animals that spread disease
research with virusesThrough research, scientists are discovering helpful uses forsome viruses.Gene therapy substitutes normal hereditary material fora cell’s defective hereditary material.The normal material is enclosed in viruses that “infect”targeted cells.The new hereditary material replaces the defective hereditarymaterial.Using gene therapy, scientists hope to help people with geneticdisorders and find a cure for cancer.