VIRUSES VIRUS: (LATIN) REFERRING TO POISON AND OTHER NOXIOUS THINGS

VIRUS STRUCTURE ENVELOPE – OUTER COVERING MADE OF PROTEIN CAPSID – CAPSULE MADE OF PROTEIN. ENCLOSES NUCLEIC ACID See next screen for typical diagram

VIRUSSTRUCTUREVIRUSSTRUCTURE

VIRUSSHAPESVIRUSSHAPES

VIRUSSIZEVIRUSSIZE

VIRUSES – Are they alive? Remember your 6 Unifying Principles: An organism must fully meet all 6 to be considered living. 1. Evolution- Viruses mutate but only within a host 2. Homeostasis- Viruses do not regulate their internal environment 3. Growth & Development- Viruses do neither on their own 4. Continuity- A virus can only reproduce using a host cell 5. Energy, Matter, and Organization- A virus has no enzymes for metabolism 6. Ecology- Viruses depend on other organisms, but other organisms do not depend on viruses

NO! Viruses are not alive! Viruses DO NOT completely meet ANY of the 6 Unifying Principles of Biology!

VIRUSES ARE: OBLIGATE INTRACELLULAR PARASITES (They are incapable of replicating except when inhabiting the inside of a cell.) Viruses are a set of encapsulated genes that can be transmitted between a defined set of host cells. To access a cell, a virus displays a receptor protein on its surface allowing it to be recognized by the host cell. Some viruses may infect just humans, others infect a variety of organisms (what viruses infect=host range)

FIRST: A virus must have a means of placing its genetic material into a host cell SECOND: Once in, the host cells normal processes are hijacked by viral proteins THIRD: The host cells DNA is reprogrammed to produce new viral proteins and genetic material at a FAST rate! Viruses use the cells:Amino acids, nucleotides, and ATP (for energy) VIRUS INFECTION

Virus Reproduction Process a.Absorption b.Entry c.Replication d.Release

BACTERIA VIRUSES Group of viruses that infect BACTERIA only Called BACTERIOPHAGE or PHAGE for short

BACTERIOPHAGEBACTERIOPHAGE

REPRODUCTION OF A BACTERIOPHAGE

Latent Viruses Latent or hidden viruses may exist in a host They are inactive They are unrecognizable by the immune system They may be triggered and enter the lytic cycle

LYTIC AND LYSOGENIC STAGES OF A VIRAL INFECTION IN BACTERIA

Lysogenic Cycle of a Temperate Virus Remains in cell Activated to produce new viruses --Does not cause disease immediately

HIV reproduction Step 1: The genome enters a special T-cell variant through two cytokine receptors

HIV reproduction Steps 2 and 3: The endogenous reverse transcriptase converts the viral RNA genome into a DNA genomes.

HIV reproduction Step 4: Special sequences and an integrase enzyme allow the viral DNA to incorporate into the host DNA

HIV reproduction Steps 5 and 6: From the viral genome, new viral protein components are made

___________________ * 200 kinds of Viruses Symptoms include nasal discharge, obstruction of nasal breathing, swelling of the sinus membranes, sneezing, sore throat, cough, and headache. Common Cold

__________________ Poliomyelitis is a crippling disease of spinal nerve cells caused by poliovirus infection. The disease can strike non-immune persons of any age but affects mainly children under the age of three, and causes paralysis in one case of every 200 to 1000 infections. Preventable by vaccination. Polio

______________ Acquired immunodeficiency syndrome, is caused by the human immunodeficiency virus, or HIV. HIV destroys the body's ability to fight infections by attacking cells of the immune system. STD AIDS

______________ The vast majority of cases reported to the Centers for Disease Control and Prevention (CDC) each year occur in wild animals like raccoons, skunks, bats, and foxes. Infects the central nervous system, causing encephalopathy and ultimately death. Rabies

______________ (Herpes simplex ) Between % of all people possess this virus and is spread through direct contact with an infected individual. Once the virus has entered the body, it cannot be removed. Only 10% of HSV1 infected people ever develop a sore. Cold Sore

_____________ Most infected children will have a rash, high fever, cough, runny nose, and watery eyes. For every 1,000 children who get it, 1 or 2 will die from it Spreads so easily that any child who is not immunized will probably get it, either now or later in life. Measles

___________ Non-cancerous skin growths caused by a viral infection in the top layer of the skin. Viruses that cause them are called human papillomavirus (HPV). STD Warts

_______________ HSV-2 usually produces only mild symptoms or signs or no symptoms at all. However, HSV-2 can cause recurrent painful genital sores in many adults, and HSV-2 infection can be severe in people with suppressed immune systems. Regardless of severity of symptoms, genital herpes frequently causes psychological distress in people who know they are infected. STD Herpes

_____________ The most common serious liver infection in the world. It is caused by the HBV virus that attacks the liver. HBV is 100 times more infectious than the AIDS virus. Yet, can be prevented with a safe and effective vaccine. Hepatitis B

C. Virologist 1. Growing cells in a controlled medium: ________________ 2. Serology 3. _____________is used to separate fragments of molecules based on charge and size. 4.. Studies bacteriophages. Tissue culture - study of biological fluids used to determine antibody response Electrophoresis

The End