The deadly microscopic world.
• Nucleic acid within a protein coat
• Jenner – smallpox vaccine
• Non-living
• No metabolism
• Cannot replicate
without a host
• No scientific name,
instead family names
Influenza virus
• Viruses that infect
bacteria –
bacteriophage
• General
Characteristics:
• Nucleic acid – either
RNA or DNA
• Outer protein capsid
• Optional features for
protection
• Envelope,
spikes, slime
layers
Capsid
protein
Tail
Tail fibers
DNA or
RNA
• Prior to replication, virus
must enter cell
• Protein on virus interlock
with surface markers on
cells
• Each virus has specific cell
to “dock” with
• EX: polio virus attaches to
nerve cells
• Lytic
1A. Virus attaches to
cell
2A. Inserts DNA
3A. Replication of
viral parts
4A. Assembly of
new viruses
5A. Cell lyses
• Lysogenic
1B. Virus attaches to cell
2B. Inserts DNA
3B. DNA integrates into
host DNA - prophage
4B. Cell replicates normally
with viral DNA altering
protein synthesis
5B. Viral DNA comes out of
the host DNA
6B. Begin Lytic Cycle
•
•
•
•
Inhibit protein synthesis of host
Open lysosomes
Bind membranes together
Create a toxic level of proteins
The human body protects itself from viruses using
antibodies and fever. Viruses prefer body
temperature.
Which of these diseases is likely to be
caused by a lytic virus?
Characteristics of some Viral Diseases
Disease
Symptoms
Incubation
Measles
Rash, Fever
9-11 days
Shingles
Pain, itching on skin
Years
Warts
Bumpy area on skin
Months
Influenza
Body aches, fever, runny nose
1-4 days
HIV
fatigue, weight loss, fever
2-5 years
Smallpox
• Last seen in 1977
• Eradicated by WHO due to obvious symptoms
and short life cycle
• CDC and Moscow
• Self-replicating
Chicken Pox
•Fluid filled blisters
•Itching and burning
•Common in kids
•Vaccine to
prevent
Herpes zoster –
shingles
•Reactivated chicken
pox
•Highly contagious
•Viral DNA remains in
neurons, dormant
•Pain, fever, skin
lesions, pus filled spots
•Can be due to sun,
stress, fever, trauma,
but main cause
unknown
Untreated
shingles
Herpes simplex 2
• Genital herpes
• Virus lives in
bottom of the spine
• Same reactivation
• Congenital herpes in
newborns
• Tingling, pain during
urination, thick discharge,
fluid filled vesicles
• Found in 25 mil Americans
Cold Sores
•Herpes simplex
•Virus lives in a
nerve in face
•Reactivated similar
to shingles
•Fever, sore throat,
mouth pain, edema
Untreated cold sores
HIV
• Retrovirus RNA  DNA
•Reverse transcriptase
• Fluid transmission
• Enters immune system
by endocytosis into
WBC
• Prevents WBC from
making a receptor (CD4)
that normally detects
pathogens
• Symptoms treated with
drug cocktail
HIV
• Exposure symptoms –
headache, sore throat,
occasional rash
• Upon reactivation – rapid
weight loss, dry cough, night
sweats, unexplained fatigue,
white spots in mouth, memory
loss
Kaposi’s Sarcoma –
HIV side affect
Burkitt’s
Lymphoma
–
HIV Side
Affect
Rabies
• Virus lives in salivary glands
of animal
• Virus destroys the nerves
• Produces Negri bodies in
brain
• Initial symptoms – tingling
and cold around bite,
nervous
• Phase II – anxiety,
photophobia, arrhythmia,
pupil dilation, difficulty
swallowing
• Gamma globulin treatment
Mononucleosis
• Fluid transmission
• “kissing disease”
• Infects WBC’s
• Enlarged lymph
nodes,
swollen spleen, sore
throat,
nausea, weakness,
fatigue
• Can last up to 6 wks
• Remains latent in
nerves
Measles
• Highly contagious
• Respiratory droplet
spread
• Nasal discharge, dry
cough, fever, headache,
pink eye, pink lesions, ear
infection
• Targeted for eradication
• MMR vaccine
Viral Hepatitis B
• Initially asymptomatic
• 1-3 month incubation
• Fever, loss of appetite,
pain, nausea, fatigue,
jaundice, swollen liver
• 3 step vaccine
Hanta Virus
• Deermice and ticks
• No human to human
• 2-3 day incubation
• Cough, pulmonary
edema, hemorrhaging,
renal failure, achy
muscles
• 60% death rate
Ebola
• 93% death rate
• Hemorrhagic fever
• High temperature
• Blood from orifices
Scott lives on a farm in the country. He started feeling
sick with flu-like symptoms. After a couple of days,
his pupils became dilated and he had difficulty
swallowing. His parents rushed him to the emergency
room. X-rays revealed that Scott has small lesions
forming on his brain. He also had an animal bite on
his lower leg.
rabies
Mary is a 23 year old college student who went to the
doctor after several weeks of general sickness. She
complained of fatigue, chills, sweating at night, a
continuous cough, and slight diarrhea. It was noted
during the exam that her glands under her arms and
in her neck were swollen. The doctors performed a
blood test.
HIV
A child, age 7, came home from school complaining
of a sore throat. Her mom took her fever, which was
1020F. The child was taken to the doctor after a
couple of days with no improvement. The doctor
noticed that she was developing a pink rash and
seemed to have an ear infection. She had not been
vaccinated with the MMR. What illness does this child
likely have?
measles
• Steroids given if severe – boost immune
function
• Usually cause fever
• Some vaccinations are weakened forms of
actual virus
• Many viruses stay in your system even
after recovery
A
B
J