Ebola Virus by pengtt

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									    Ebola Virus
Microbiology 401
    Fall 2007
Shahrzad Morim
Monica Delgado
  Janine Gilkes
                     Case Study- Ebola Virus
• VECTOR- the State Research Center for Virology and Biotechnology
•   Biosafety Level 4 Lab
•   Designed specifically to create genetically altered viruses
•   Bioweaponization-
     –    potentially aerosolized
•   U.S. was considered “deep target”

• The former Soviet Union
• Program:
     – active state-supported bio-weapon research/production (1970’s to
       mid 90’s)
     – worked with incurable pathogens
       While working to develop a vaccine against Ebola virus, one of the
       scientists accidentally stuck herself with a needle contaminated with
       virus. She contracted Ebola hemorrhagic fever and died.
                       Ebola Virus
                    Brief Background
 Family Filoviridae
 Genus Ebolavirus
 History
     First emerged in 1976
     Ebola River Valley, Africa
 Sub-types (well-known)
    1.   Zaire
    2.   Sudan
    3.   Reston
    4.   Tai (Ivory Coast)
 Classification
     Enveloped
     SS negative-sense RNA
 Structure
     Long, filamentous, “thread-like”
      structure of a filovirus
     “U” or “6” appearance
                         Ebola Virus

• Structure-function analysis of
  the soluble glycoprotein, sGP,
  of Ebola virus
   – Transmembrane protein,
   – GP gene encodes the soluble
     glycoproteins sGP and Delta-
• Genome has 7 genes:
   – NP, VP35, VP40, GP, VP30,
     VP24, and L
• GP1 Viral Entry
• GP2 Fusion and Entry
     • Likely pH dependent
 Currently Believed Animal Reservoir
            of Ebola Virus?
• Despite extensive studies, the natural and animal reservoir is
    – Seems to be the rain forests on the African continent and in the
      Western Pacific.
• Non-human primates as a source of infection for humans
    – Carcasses of gorillas, chimpanzees and duikers during outbreaks in
      2001 and 2003
    – High mortality from infection in these species disqualifies them from
      acting as reservoirs
• Other considered Reservoirs
    – Plants, arthropods, and birds
• IRD researchers have identified bats as a potential natural reservoir
  of Ebola virus
    – Of 24 plant species and 19 vertebrate species experimentally
      immunized with Ebola virus, only bats became infected.
        • No clinical signs were observed in these bats
        • This is characteristic of a reservoir species
Currently Believed Animal Reservoir of
             Ebola Virus?
• Current proposal
  – Bats
     • Good vectors
  – If bats are among the
     • Likely to pass virus to         • In 2001-03
       great apes  humans                – Survey of 1,030 animals
     • May infect humans                    (including 679 bats) from
       directly                             Ebola-affected areas
  – Dry season                            – Found three bat species
     • More contact because of            – Viral genome fragments
       food competition                     (RNA) in the liver and spleen
     • Bats’ immune systems               – Evidence of immune
       modified                             response
                                              • antibodies against virus in
           • Virus reproduces easier
                                                the serum
           Transmission of Ebola Virus
•   Direct contact
     – Blood , secretions , organs
•   Unsterilized needles
•   Burial ceremonies
•   Documented human infections
     – Handling of infected chimpanzees,
        gorillas, forest antelopes
•   Airborne transmission
     – limited evidence of human-human
•   Incubation period
     – 2 to 21 days
•   Contagiousness
     – Not during early stages
     – As the illness progresses, bodily
        fluids represent an extreme
           Symptoms of Ebola Virus
Initial Signs              Progressed Symptoms
                           • Vomiting
• Fever (at least 102°F)
                           • Diarrhea
• Weakness & exhaustion    • Extensive bleeding
• Pain                         – Red eyes
     – Severe headache             • hemorrhage of sclerotic
     – Muscles & joints
                               – From mouth, nose, eyes,
     – Abdominal pain            rectum & mucouse
• Sore throat                    membranes
                           • Maculopapular rash
• Nausea
                               – Spreads over the body (often
• Dizziness                      hemorrhagic)
                           • Other secondary symptoms
                               – Hypotension , Hypovolemia ,
                               – Organ damage
                               – Internal and external bleeding
                Tissue Damage leads to
•   Hemorrhagic fever syndrome
•   late symptoms:
      – toxic shock, hemorrhaging
•   Direct tissue damage
           • liver, combined with
             massive viremia
•   Disseminated intravascular
•   Endothelial susceptibility
•   Subverts innate and adaptive
    immune responses
•   Terminal stages
      – diffuse bleeding, and
         hypotensive shock accounts for
         many Ebola virus fatalities
• Specialized laboratory test on
  blood specimens for detection
   – Antigens
   – Genes of the virus
   – Antibodies against the
• New techniques
   – Non-invasive methods:
     saliva and urine samples
• Diagnosing
•      ELISA Assay
•      IgM ELISA
•      PCR                         Courtesy of:
                Infection Prevention and
                 Lab Safety Precautions
•   Infection Prevention
    –   Isolation
    –   communication
    –   Limit direct contact
    –   Monitor those who had lose contact
        with infected
    –   Disinfect reusable equipment
    –   Sterilize equipment
•   Lab Safety Precautions
    –   Education about organism
    –   Sterile environments
    –   Protective clothing
    –   Proper disposal of waste products
    –   Limit contact with contaminated
        medical equipment
    –   Communication
           Current Research On Vaccines
•   One study found that guinea pigs were protected from
    Ebola virus infection by immunization with plasmids
    containing the viral genes for either the secreted or
    transmembrane forms of the viral glycoprotein (GP).
    This protection was correlated with antibody titer and
    antigen-specific T-cell responses to secreted GP or
    membrane GP.

•   Another study found that harmless-Ebola-like particles
    (eVLPs) could confer immunological protection from
    Ebola virus infection. These eVLPs were found to be
    immunogenic both in vitro and in vivo. Mice were
    vaccinated with these eVLPs, and developed high
    titers of Ebola virus specific antibodies, including
    neutralizing antibodies. Additionally, all the mice in
    the study were protected from Ebola virus inoculation.
• Biological warfare (BW) aka
  biological weapons, is the use of
  any pathogen, bacteria or virus as
  a weapon of war.

• After initial release of virus,
  secondary infections may occur
  as a result of infected individuals
  traveling from areas of
  contamination to other locations.

• In 1972 the Biological Weapons
  Convention outlawed creation
  and storage, but not usage, of
  these weapons.
    Benefits and Hazards of U.S Aid
• Benefits of US Aid                 • Hazards of US Aid

- Russian Allies                     - VECTOR removed from
- Collaborative efforts in finding      biowarfare threat list;
  a cure for Ebola                      however, 4 other weapons
- Decreased Fear                        labs exist with no U.S.
- A cut of the profits
                                     - Difficult to verify whether
                                        former Soviet Scientists are
                                        using the American supported
                                        research for peaceful purposes
                                     - Lack of Accountability
          Which is more dangerous
         As a Potential Bio-Weapon?
Ebola Virus                              Smallpox Virus
   – CDC classifies it as:             – CDC classifies as
       • Category A bioterrorism            • Category A bioterrorism agent
         agent                         – Incubation period between
                                         contraction and the first obvious
   – Sudden, severe onset of             symptoms of the disease is usu. 12-14
     symptoms                            days
   – Believed to hide out in           – Initially vague, flu-like symptoms, turn
     animals                             into severe symptoms (fever, severe
                                         pain, characteristic rash)
   – No approved vaccine or
                                       – Humans are the only natural host
                                       – Historic death rate of 1 in 3
   – Short incubation period           – Vaccination in 1967
       • May kill victim before          • Effective if administered up to 4 days
         transmitted to others (high       after viral exposure and before rash
         death rate)                       appearance
       • Outbreaks seem to burn out – No effective treatment
         quickly                     – In 1979, WHO declared eradication
         Smallpox (Variola Virus)
• Genus: orthopoxvirus
• DS DNA: one of the largest viral genomes
• Relatively stable
  – If aerosolized, infective for at least several hours
    (without sunlight or UV exposure)
• Acute contagious disease
  – Two main forms
     • Variola major (30% fatal)
     • Variola minor (<1% fatal)
  – Two rare forms (almost always fatal)
     • Hemorrhagic
     • Malignant
           Which is more dangerous
          As a Potential Bio-Weapon?
• CDC: an agent must have the following properties to be
  used for a maximum credible event
   –   Be highly lethal
   –   Be easily produced in large quantities
   –   Be communicable from person to person
   –   Have no treatment or vaccine
• Smallpox
   – Extremely contagious
        • Transmission through air
   –   Can be produced in large scale
   –   Can spread in any climate or season
   –   Contaminates in a short time
   –   Preventive measures/treatments
        • Routine smallpox vaccination was discontinued in the U.S. in 1972
        • Limited vaccine with questionable potency
        • Vaccine complications
 1) Adamcek, K., Eanes, M., Shaw, S., Virology Project: Ebola Virus. Retrieved: 11/8/07
• http://www.biosci.ohiou.edu/virology/Ebola
2) Miller, J. Russian Scientist Dies in Ebola Accident at Former Weapons Lab. The New York Times.
     Published: 5/25/2004. Retrieved: 11/12/2007
• http://query.nytimes.com
3) Pappalardo, J. From Russia, with bugs [US subsidizing Russian Biological Warfare Lab]. Dallas
     Observer. Published: 6/22/2000. Retrieved: 11/14/07
• http://freepublic.com
4) “Biological Warfare.” Wikipedia: The Free Encyclopedia. Retrieved: 11/12/07
• www.wikipedia.org
5) Emerging Infectious Diseases. National Center for Infectious Diseases. Vol. 5, No.4, July-Aug 1999.
     Retrieved 11/8/07
• http://www.cdc.gov/ncidod/eid/vol5no4/pdf/v5n4.pdf
6) Tanna, J.H, Preventing “Dark Winter”-The Public Health System’s Role in Strengthening National
     Security. Vol. 1, No.4, Spring 2002. Retrieved 11/8/07
7) Leroy, E., Fruit Bats a Reservoir for Ebola Virus. Indigo Base, IRD. November 2005. Retrieved 11/8/07
8) World Health Organization. Ebola Haemorrhagic Fever. Retrieved 11/8/07
•     http://www.who.int/mediacentre/factsheets/fs103/en/
9) Hoenen et al. Ebola Virus: Unravelling Pathogenesis to Combat a Deadly Disease. Trends Mol. Med. May 2006, 12(5): 206-215
10) Leroy, EM, Kimulugui, B, Pourrut, X et al. Fruit Bats as Reservoirs of Ebola Virus. Nature. 2005. 438:575–576
11) Pourrut, X, Kumulungui, B, Wittmann, T et al. The Natural History of Ebola Virus in Africa. Microbes and Infection. 2005.
12) Retrieved 11/11/07
•     http://www.nytimes.com/packages/html/health/20030506_Ebola_COMPARE/sci_Ebola_COMPARE_01.html#
13) World Health Organization. Smallpox. Retrieved 11/8/07
•     http://www.who.int/mediacentre/factsheets/smallpox/en/
14) September 2003, p. 9733-9737, Vol. 77, No. 18
15) BMC Microbiology 2003 3:6 doi:10.1186/1471-2180-3-6
16) www.biomedcentral.com/1471-2180/3/6/figure/F3
(Courtesy of http://www.ncbi.nlm.nih.gov/ICTVdb/Images/Murphy/ebola_cell.htm
17) World Health Organization
•      http://www.who.int/mediacentre/factsheets/fs103/en/
•     Provisional Revision: 2007
18) Leroy, Eric M., et al. Multibple Ebola Virus Transmission Events and Rapid Decline of Central African Wildlife. Science 303: 387
      -389. 2004
19) Facts sheet: Community Health Administration
•     http://edcp.org/factsheets/ebola.html Journal of Virology
Thank you!

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