Viruses :Tiny Biological Particles Size video

Viruses are abiotic  They do not meet all of the 5 characteristics of living things….  1) viruses can not obtain and use energy  a) they do not exchange gasses  b) they do not take in nutrients/water  2) viruses can not reproduce on their own  a) host cell makes the copies of viruses  3) viruses are not cells

Viruses composed of:  1) Protein covering  2) Nucleic Acid either…  a) DNA (deoxyribonucleic acid)  b) RNA (ribonucleic acid)  ** no water

Host cells  Cells that have been invaded by viruses or virus DNA/RNA  Host cell is forced to make virus DNA/RNA  Host cell is forced to make virus proteins  These parts are assembled in the host cell to create new virus particles

2 methods of viral attack  1) lytic cycle: immediate take over of cell  a) destruction of host cells cause disease symptoms  2) lysogenic cycle: covert attack  a) virus DNA blends in with host cell DNA  b) when host cell divides the virus divides too  c) stress or illness cause virus to switch to lytic cycle and cause disease symptoms

Lytic cycle examples  1) Rhino virus…  common cold  2) Influenza virus…  flue virus

Lysogenic cycle examples  Herpes simplex I …  cold sores  Varicella…..  chicken pox (lytic) shingles (lysogenic)

Viruses we get immunized against  Measles  Mumps  Chicken pox can be fatal in adults  influenza

Overview of humoral immune response 

Vaccinations  Activate our acquired immune system  Cause creation of memory cells  Prevent us from showing symptoms of disease even if we are exposed to it  Prevent us from transmitting disease to others  Can eradicate disease causing agents from the face of the earth!

Smallpox virus  wiped off the face of the earth, except for samples held in labs in the U. S. & Russia  Smallpox was an entirely human disease -- it didn't infect any other animal or insect on the planet. Thus, once vaccination eliminated the chances of the virus spreading among the human population, the disease disappeared; in fact, the United States hasn't vaccinated for smallpox since  Although smallpox was one of the most devastating illnesses in human history, killing more than 300 million people worldwide during the 20th century alone, scientists declared the world free of smallpox in The naturally occurring disease has been eradicated, but fears remain about the smallpox samples being used as bioweapons.  1 OR 2 PEOPLE IN 1 MILLION WHO RECEIVE THE VACCINE MAY DIE AS A RESULT BECAUSE THIS IS A LIVE VACCINE OF A POX VACCINE SIMILAR TO SMALL POX ( %)

How we make vaccinations  Viruses are identified & isolated from host  Host cells must be found in which viruses can reproduce ( eggs, tissue culture)  Viruses are injected into host cells, millions of viruses are produced.  Viruses are isolated from host cells/purified  Viruses are either killed or weakened  8, _ ,00.html 8, _ ,00.html

Live Attenuated vaccinations  living microbes weakened = no symptoms.  closest thing to a natural infection, so strong immune responses  often confer lifelong immunity  The remote possibility that an attenuated microbe could mutate back to disease causing  Viruses attenuated by growing them in cells in which they do not reproduce very well.  As they evolve to adapt to the new environment, they become weaker with respect to their natural host, human beings.

 Between 1990 and 1995 in the UK, there were 5433 suspected adverse reactions to all the vaccines given to children under 15 years of age - out of around 80 million doses of vaccine - that's % of cases. Only a tiny number of those were serious.

Live Attenuated vaccinations  living microbes weakened = no symptoms.  closest thing to a natural infection, so elicit strong cellular & antibody responses  often confer lifelong immunity  The remote possibility that an attenuated microbe could mutate back to a virulent form  Viruses attenuated by growing them in cells in which they do not reproduce very well.  As they evolve to adapt to the new environment, they become weaker with respect to their natural host, human beings.

Inactivated Vaccinations  Produced by killing the microbe with chemicals, heat, or radiation.  More stable  Dead microbes can’t mutate back to disease- causing state  Most stimulate a weaker immune system response  booster shots needed

Subunit Vaccines  include only antigen parts of microbe  Some only epitopes.  Much lower chances of adverse reactions  Scientists ID antigens that activate immunity  They grow microbes & use chemicals to break them apart and gather the important antigens.  Antigens multiplies by recombinant DNA tech.  Scientists inserted hepatitis B antigen genes into common baker’s yeast. The yeast then produced the antigens, which scientists purified for use in the vaccine.

 Chances are you never had diphtheria. You probably don’t know anyone who has suffered from this disease, either. In fact, you may not know what diphtheria is. Similarly, diseases like whooping cough (pertussis), measles, mumps, and German measles (rubella) may be unfamiliar to you. In the 19th and early 20th centuries, these illnesses struck hundreds of thousands of people in the United States each year, mostly children, and tens of thousands of people died. The names of these diseases were frightening household words. Today, they are all but forgotten. That change happened largely because of vaccines

Different infectious agents 