Viruses

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Viruses Bacteria
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A virus is a nonliving particle with a simple
structure.Composed of a nucleic acid (DNA or
RNA) surrounded by a protein coat.
Virus that infects bacteria
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Virus Structure

• Capsid - The capsid is the protein shell that
  encloses the nucleic acid Three functions
• 1) it protects the nucleic acid from digestion by
  enzymes,
• 2) contains special sites on its surface that
  allow the virus to attach to a host cell, and
• 3) Allow virus nucleic acid penetrate the host
  cells membrane and, in some cases, to inject the
  infectious nucleic acid into the cell's
  cytoplasm.
• Envelope - Surrounds the capsid. Composed of two
  lipid layers interspersed with protein molecules

Or RNA
Or RNA
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• Viral Nucleic Acid
• The nucleic acid of each virus encodes the
  genetic information for the synthesis of all
  proteins.
• Only a few groups of viruses use DNA.
• Most viruses maintain all their genetic
  information with the single-stranded RNA.

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Viruses, such as the influenza virus, that have
RNA as their genetic material mutate more often
that DNA viruses.
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Lytic Cycle

1. The virus attaches to a host cell and injects its
   nucleic acid into the cell.
2. The viral nucleic acid is immediately replicated,
   eventually causing the host cell to burst,
   releasing new viral particles.
3. These new viruses then attack other cells.

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Lysogenic Cycle

• After the virus embeds its nucleic acid into the
  chromosome of the host cell, the viral nucleic
  acid is replicated along with the host cells
  DNA.
• Then the virus becomes dormant, sometimes for
  years without the host knowing.
• The virus may suddenly become active, resuming
  the lytic cycle, which will eventually destroy
  the host cell.

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Overview Lytic and Lysogenic cycles
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Are viruses alive?

• Can They
• Reproduce?
• Obtain and use energy?
• Grow, develop, and die?
• Respond to the environment?

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Vaccines

• Made from parts of a virus.
• Then when our bodies see the virus again it
  recognizes and fights the virus.
• Antibiotics do not work on viruses!
• Most vaccines contain purified fragments taken
  from killed bacteria or viruses. Some vaccines
  contain live viruses, but in a very weak form
  that dos not cause disease.

stimulates the bodys immune response
"teach" the immune system how to recognize and
fight bacteria and viruses
CLIP
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• VACCINE CLIP

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Diseases Caused by Viruses

• Smallpox
• Ebola
• Hantavirus
• Herpes
• Lassa Fever
• Mononucleosis
• West Nile
• Yellow fever
• Cancer

• Influenza
• Measles
• Chickenpox
• Polio
• HIV
• Mumps
• Rabies
• Hepatitis
• Common cold

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Influenza
contagious respiratory illness

• 1918 pandemic 20 to 40 million people

More people died of influenza in a single year
than in four-years of the Black Death Bubonic
Plague from 1347 to 1351. Known as "Spanish Flu"
or "La Grippe" the influenza of 1918-1919 was a
global disaster
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Polio

• What's the Future of Polio?Through intensive
  vaccination programs, a coalition of
  organizations in 1999 decided to work toward
  world eradication of polio by 2005. Between 1988
  and 1998, wild-type polio was eliminated from
  North America, South America, and Europe. But
  polio still exists in Africa, as well as India
  and some of its neighboring countries.

• Polio is a contagious, historically devastating
  disease that was virtually eliminated from the
  Western hemisphere in the second half of the
  twentieth century. Although polio has plagued
  humans since ancient times, its most extensive
  outbreak occurred in the first half of the 1900s
  before the vaccination, created by Jonas Salk,
  became widely available in 1955.
• People who have abortive polio or nonparalytic
  polio usually make a full recovery. However,
  paralytic polio, as its name implies, causes
  muscle paralysis - and can even result in death.
  In paralytic polio, the virus leaves the
  intestinal tract and enters the bloodstream,
  attacking the nerves (in abortive or asymptomatic
  polio, the virus usually just stays in the
  intestinal tract). The virus may affect the
  nerves governing the muscles in the limbs and the
  muscles necessary for breathing, causing
  respiratory difficulty and paralysis of the arms
  and legs. Although the acute illness usually
  lasts less than 2 weeks, damage to the nerves
  could last a lifetime.

Clip
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Ebola Virus 
The onset of illness is abrupt and is
characterized by fever, headache, joint and
muscle aches, sore throat, and weakness, followed
by diarrhea, vomiting, and stomach pain. A rash,
red eyes, hiccups and internal and external
bleeding may be seen in some patients.
native to the African continent.
People can be exposed to Ebola virus from direct
contact with the blood and/or secretions of an
infected person contact with objects, such as
needles, that have been contaminated with
infected secretions
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Human Immunodeficiency Virus
HIV attacks some of the cells that are vital to a
healthy immune system, including the white blood
cells known as T-helper cells or CD4 cells.
AIDS means 'acquired immune deficiency syndrome'.
It is a condition that sets in when the HIV virus
has killed so many T-helper cells that the immune
system is no longer able to recognize and react
to attacks from everyday infections.
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Lassa Fever
single-stranded RNA virus and is animal-borne.
The Mastomys rodents shed the virus in urine and
droppings. Lassa fever may also spread through
person-to-person contact. This type of
transmission occurs when a person comes into
contact with virus in the blood, tissue,
secretions, or excretions of an individual
infected with the Lassa virus.
Signs and symptoms of Lassa fever typically occur
1-3 weeks after the patient comes into contact
with the virus. These include fever, retrosternal
pain (pain behind the chest wall), sore throat,
back pain, cough, abdominal pain, vomiting,
diarrhea, conjunctivitis, facial swelling,
proteinuria (protein in the urine), and mucosal
bleeding.
The most common complication of Lassa fever is
deafness. 1 of infections with result in death.
The number of Lassa virus infections per year in
West Africa is estimated at 100,000 to 300,000,
with approximately 5,000 deaths. In some areas of
Sierra Leone and Liberia, it is known that
10-16 of people admitted to hospitals have
Lassa fever, which indicates the serious impact
of the disease on the population of this region.
West Africa
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Chickenpox

• Chickenpox is a very contagious viral disease
  that causes an itchy outbreak of skin blisters.
• The chickenpox virus spreads from person to
  person by direct contact with fluid from broken
  chickenpox blisters.
• Chickenpox is usually a mild disease. However, in
  adults and children with weakened immune systems,
  chickenpox can cause serious complications and
  even death.
• A vaccine is now available to prevent chickenpox.

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Hantavirus
A person may be exposed to hantavirus by inhaling
dust after disturbing nests or breathing in
closed spaces inhabited by infected mice. The
deer mouse (Peromyscus maniculatus) is the main
carrier of hantavirus however, other wild
rodents can cause problems as well.
The first symptoms are fever, chills, muscle
aches, and sometimes nausea, vomiting, and
abdominal pain. The muscle aches are often
severe, and occur in the thighs, hips, back and
sometimes the shoulder. Some patients will
develop coughing and shortness of breath within a
few days. Others may go for as long as a week
with the other symptoms before developing a cough
and shortness of breath, followed by the abrupt
onset of respiratory distress, often severe and
fatal.
Mortality is about 40 to 50 percent
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Measles

• Diseases of childhood that causes a skin rash. 
• Serious complications, such as pneumonia, croup
  or encephalitis, can occur.
• The disease starts with a cold, fever, cough,
  conjunctivitis (red eye) and fatigue.  Three days
  later, a red blotchy rash starts on the face -
  then spreads to the rest of the body, including
  the feet.  The fever starts to go down on the
  second or third day of the rash.  There may be
  some fine peeling of the skin after the rash
  fades. Most patients are ill for about seven
  days
• IS IT CONTAGIOUS?VERY. It is most common in late
  winter and early spring.  Most people have been
  exposed to the disease 10-12 days before they
  have any symptoms. Spread by coming in contact
  with the saliva of someone who has the disease
  through coughing, kissing or sharing of eating
  utensils.
• Once you have had a case of measles you have
  lifetime immunity (protection) to the disease.

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Mumps
Mumps is an infectious disease that causes
swelling of the saliva-producing glands near the
ears.  Can last 7-10 days
The most common symptom is painful swelling in
front of and below the ears.  Often, there is
pain when eating or moving the jaw.  Some people
have headaches, loss of appetite, fever and a
tired feeling about a day before the swelling. 
One side of the face usually swells before the
other.  In males past puberty, a problem that is
associated with mumps is orchitis (swelling of
the testicles).
Mumps is spread by contact with the saliva of
someone who has the disease.  It is contagious
until all the swelling is gone.  Mumps occurs
year-round, but is more common in the winter and
spring.
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Rabies

• Infects the central nervous system, causing
  encephalopathy and ultimately death. Early
  symptoms in humans are nonspecific, consisting of
  fever headache.
• As the disease progresses, neurological symptoms
  appear and may include insomnia, anxiety,
  confusion, slight or partial paralysis,
  excitation, hallucinations, agitation,
  hypersalivation, difficulty swallowing, and
  hydrophobia. Death usually occurs within days of
  the onset of symptoms.

The principal rabies hosts today are wild
carnivores and bats..
Rabies immune globulin and five doses of vaccine
given over a 4-week period typically
RNA virus.
Most often transmitted through the bite of a
rabid animal
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Smallpox

• Infection usually occurred by inhalation of virus
  
• acute, with fever, malaise, headaches, and
  backaches. The initial toxemia phase lasted 4-5
  days. On about the third or fourth day, the
  characteristic rash appeared. First, it appeared
  on the buccal and pharyngeal mucosa, the face,
  and the forearms. Within a day, it spread to the
  trunk and lower limbs.
• The lesions usually protruded from the skin and
  are firm to touch. About 8 weeks after onset of
  the rash, the lesions dried up and became crusted
  by day 14. By the end of the third week, most
  crusts had fallen off, with the exception of the
  palms and the soles. The outcome of infection was
  either death or recovery with immunity.

In 1966, the World Health Organization started a
program for the worldwide eradication of
smallpox. Through intensive case finding and
vaccination of direct and indirect contacts, the
disease was finally eradicated on December
9,1979.
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Hepatitis
Hepatitis C Before a blood test was discovered in
1989 to screen for HCV, this was the most
frequent hepatitis to be acquired from blood
transfusions and blood products. Up to half of
those with chronic disease will go on to develop
liver failure and need a transplant. Each year,
8,000 to 10,000 people die in the United States
because of hepatitis C-related cirrhosis or
HCV-related liver cancer.
Hepatitis A mainly transmitted by contaminated
food and water.
Hepatitis is a disease that impairs liver
function either temporarily or permanently,
sometimes even leading to death. It can be
initiated by a host of factors, but primarily by
viruses. Drugs also can cause hepatitis but when
the specific drug is discontinued, the liver
usually returns to normal.
Hepatitis B This type is essentially a
blood-borne virus with other bodily fluids being
infectious, notably semen and saliva, and is
often transmitted from mother to fetus.
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Herpes

• Infection caused by the Herpes Simplex Virus
  (HSV), which resides in the nerve ganglia after
  the initial exposure to the virus.
• Because the virus is so effective at "hiding out"
  in the nerve cells, the body is never able to
  eliminate the herpes virus completely. Instead,
  after the initial infection, the body produces
  antibodies which show up in the blood stream.
• Blood tests which indicates the presence or lack
  of these antibodies.
• The antibodies make it easier for the body to
  recognize and attack the virus when it re-emerges
  from the nerve cells in the form of an outbreak.
• For this reason, out breaks following the primary
  outbreak usually diminish in frequency and
  intensity over time.
• Some people may never have another outbreak.

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• How germs are spread
• Clip

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EXTRAS

• Prion-is a type of infectious agent made only of
  protein.
• Chronic wasting disease, (in deer and elk), mad
  cow disease
• All of these diseases affect the structure of the
  brain or other neural tissue, and all are
  untreatable and fatal.

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• Viroids-small naked single-stranded RNA molecules
  that infect plant cells and cause disease.
• Smaller than viruses, viroids are not enclosed in
  a protein coat of any kind.
• They generally consist of less than 400
  nucleotides and do not contain any genes.

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BACTERIA
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Shapes
Different kinds of bacteria have different shapes.
Round
Spiral
Rod
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Structure
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Gram Staining
Method scientist use to determine cell wall type
in bacteria
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Pili
Helps the bacteria stick to surfaces.
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1. Flagella
2. Snake or spiral
3. Glide on slime
4. Non-motile

Movement
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Nutrition

• Heterotrophic
• Autotrophic
• Photoautotrophic
• Chemoautotrophic
• 3.Photoheterotrophic

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With or Without Oxygen
Cannot Have Oxygen
Must Have Oxygen
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E. coli undergoing conjugation
Conjugation tube
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Binary fission
duplication of the chromosome followed by the
bacterial cell splitting into two cells.
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CLIP
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ENDOSPORES
The spores may remain dormant for years until
conditions become favorable. In
favorable conditions, the spore splits open and
the bacteria rapidly reproduce.
Some bacteria can form endospores that allow them
to wait out harsh environmental conditions.
Some disease causing bacteria (like Anthrax) are
capable of causing an infection 1300 years after
forming their endospore!
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Endospores are a method of survival.
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ENDOSPORE FORMATION
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Diseases caused by Bacteria

• Cholera
• Diphtheria
• Leprosy
• Lyme disease
• Meningitis
• Cat-scratch
• Strptococcus
• Scarlet Fever

• Plague
• Pneumonia
• Syphilis
• Tetanus
• Tuberculosis
• Typhoid fever
• Samonella
• Rocky Mountain Spotted Fever

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clip
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Alexander Fleming
Discovered Penicillin
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antibiotics can be used to destroy bacterial
cells
Usually inhibits cell wall growth or protein
synthesis
CLIP
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• There are different ways to prevent a bacterial
  infection.
• Skin and surfaces that have been in contact with
  raw meat should be washed thoroughly, food should
  be cooked properly, and contaminated water should
  be boiled.
• Avoid contact with an infected organism or
  organisms that carry disease-causing
  microorganisms.
• Plague swept across Europe in the Middle Ages,
  half of the population died.
• Bacteria transmitted through the bite of a flea.

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• EOCT
• QUESTIONS

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The outer layer of a virus is made of

• A) carbohydrates
• B) lipids
• C) nucleic acids
• D) proteins

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Meningitis is an infection within the spinal
fluid that may be caused by either viruses or
bacteria. Which of the following would be a
treatment for bacterial meningitis but NOT for
viral meningitis?

• A vaccinations
• B blood transfusions
• C vitamin C
• D antibiotics

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Influenza measles, and chickenpox are diseases
caused by

• A bacteria
• B fungi
• C protozoa
• D viruses

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Why is food preserved by canning in glass
containers normally safe for later
consumption? A The glass allows solar radiation
to kill the bacteria that were in the food. B
Bacteria are destroyed by extreme heat in the
glass container. C Bacteria are removed from the
food before it is placed in the glass
container. D The glass container prevents oxygen.
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Understanding Bacteria
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