Transcript Ebola Virus - FM Faculty Web Pages

Ebola Virus
By: Giselle and Matt
Family of Ebola Virus
Filoviridae
• Comes from the Latin filo meaning
“threadlike”
• Two members
1. Marburg
2. Ebola Virus
 Five Species
1.
2.
3.
4.
5.
Zaire
Sudan
Reston
Ivory Coast
Bundibugyo
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Filovirus
Very in shape
• long sometimes branched filaments
•Shorter filaments shaped like a “6” or “U”
sometimes a circle.
•Filaments measure from 80nm (Average) to
14,000nm.
•Enveloped virion
•Single-strand negative sense RNA
Proteins
Five proteins in filoviruses
•Glycoprotein
•Nucleocapsid
•Transcriptase-polymerase
•RNA dependent RNA transcriptase polymerase
•matrix
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History
Discovered in 1974.
• Received it named from the first
victims found from the Ebola River
Valley in the Democratic Republic of
the Congo.
Strains
Zaire
•90% mortality rate.
• 276 out of 300 died.
Sudan
•50% morality rate.
•150 out of 285 died.
Reston
•Found 1989
•infected monkeys in the Philippines
•The only airborne strain of Ebola virus.
•Later found that this strain is not harmful to humans but very devastating to monkeys.
•However four people known to have developed antibodies to this strain.
Ivory Coast
•Found in monkey being autopsied by a scientist in 1994.
•Scientist became ill from the virus but survived.
Bundibugyo
•Most recently discovered strain of Ebola virus.
•Has less power to kill when compared to other strains.
•25%morality rate.
•37 out of 150 died.
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Symptoms
•High fever
•Muscle aches
•Sore throat
•Fatigue
Followed by:
•Stomach pain
•Diarrhea
•Rash
•Vomiting
Some may experience:
•Internal and external bleeding
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http://www.youtube.com/watch?v=3FI5KYk62bs&feature=channel
Virion Replication
•
Enveloped viron
–
•
membrane surrounding the virus.
Phospholipids bilayer
– With embedded proteins (spikes)
• Facilitate penetration of the virus into the host’s cell’s cytoplasm.
•
Adsorption
– Spike shape complements a host’s cell protein.
– Ebola attaches and is endocytosed into the cell.
•
Penetration
1. The virus membrane fuses to the hosts membrane.
2. Nucleocapsid is released into the cytoplasm.
•
Synthesis
– Occurs in the cytoplasm
– Make more
1. Capsid proteins
2. Genome
–
Host uses host mechanisms
• Transcription- used to synthesize (-) sense RNA for encapsulation
• Translation- make more viral proteins.
Virion Replication Continued..
•
Maturation
– Assembly of new virions made inside the cytoplasm.
•
Release
– The Ebola virus uses the TSG101 pathway.
• This is the same pathway as HIV .
– Exocytosis
• Newly formed Ebola Virus bud from cell membrane and released.
• Infected host cell remains alive to continue viral replication.
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Cell Ebola targets
The main cells it will attack are
•fibroblastic reticular cells
•which form much of the connective tissue.
•These cells are under the skin and close by to blood and lymph vessels.
•This allows the virus to spread easily in the body.
Ebola will then go on and attack any other connective tissue and epithelial tissue.
•This is what causes the hemorrhaging portion of the symptoms.
•The virus then moves on to liver and kidney cells.
Evading the Immune System
Ebola once again works similar to HIV in how it evades the immune system.
•There is a cellular protein called tetherin
•This protein does not save the infected cell.
•It prevents the virions from budding off into endosome and escaping.
Ebola disables tetherin like HIV does.
•This allows the virus to bud out of the cell.
Transmission from host to host
The virus spreads similar to HIV.
– It spreads through bloody fluids such a blood, semen, and feces.
– The only exception is the Reston Ebola virus
• shown to be air born
• lucky for us it only attacks monkeys.
• The outbreaks usually happen when a human gets the disease from an animal.
– This is known as a zoonotic infection (from animal to human).
– Then the infected person infects family and friends and hospital staff.
•
This can be contributed to the fact these outbreaks happen some of the poorest
nations .
– In the nations of Africa there is a severe lack of resources especially in medicine. The
nurses have limited or no personal protective equipment.
– They also have to reuse syringes that do not get cleaned properly.
– This not only spreads Ebola, but it also spreads HIV and other diseases.
Vaccine
Experimental vaccine
•Being evaluated on infected primates.
•Vaccine has a recombinant inhibitor factor.
•33% survival rate
•Although this experimental vaccine shows promising
results there are no anti-viral drugs available for clinical
use.
Biohazard
The lack of a cure and vaccine makes Ebola a level 4 biohazard.
•Level 4 biohazards are kept in special labs known as level 4 biosafety labs.
1. The first level is for microbial agents that do not cause harm to humans.
2. The second level is for microbial agents that do cause human disease
but transmission is limited.
3. The third level is for microbial agents that cause severe infections and
easily transmitted to humans.
4. The fourth level is for microbial agents that have no cure or vaccine.
They are also highly contagious and pose a significant health threat.
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http://www.youtube.com/watch?v=OPaUGAx873U&feature=related
Treatment
Isolation of the virus for 2-22 days.
•There is no treatment for filoviruses.
•Treatments of symptoms:
•Keeping fluid and electrolyte levels
balanced.
•Maintaining blood pressure and oxygen
levels.
•Blood transfusions.
•Cause of death:
•Normally
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•Organ shock or failure associated with fluid and blood loss.
•It is still unknown why some infected recover while others die. But those that die have not
had a significant immune response before death.
Bioterrorism
The possibility of a bioterrorist
attack using Ebola is unlikely.
•The natural reservoir is
unknown.
•The virus is held in highly
guarded labs.
Ebola would make an effective
Weapon because of:
•the fear it would instill in
people.
•how quickly the virus kills and spreads.