Ebola VirusEbola Virus

Microbiology 401Fall 2007

By:Shahrzad MorimMonica Delgado

Janine Gilkes

Case Study- Ebola VirusEbola Virus• VECTOR- the State Research Center for Virology and Biotechnology

branch• 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 VirusBrief Background

Family Filoviridae Genus Ebolavirus History

First emerged in 1976 Ebola River Valley, Africa

Sub-types (well-known)1. Zaire 2. Sudan3. 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(1,2)– GP gene encodes the soluble

glycoproteins sGP and Delta-peptide.

• 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 unknown– 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

culprits• Likely to pass virus to

great apes humans• May infect humans

directly– Dry season

• More contact because of food competition

• Bats’ immune systems modified • Virus reproduces easier

• In 2001-03– Survey of 1,030 animals

(including 679 bats) from Ebola-affected areas

– Found three bat species – Viral genome fragments

(RNA) in the liver and spleen – Evidence of immune

response • antibodies against virus in

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 biohazard

Symptoms of Ebola VirusInitial Signs • Fever (at least 102°F)• Weakness & exhaustion • Pain

– Severe headache– Muscles & joints– Abdominal pain

• Sore throat• Nausea• Dizziness

Progressed Symptoms • Vomiting• Diarrhea• Extensive bleeding

– Red eyes• hemorrhage of sclerotic

arterioles– From mouth, nose, eyes, rectum &

mucouse membranes• Maculopapular rash

– Spreads over the body (often hemorrhagic)

• Other secondary symptoms – Hypotension , Hypovolemia ,

Tachycardia – Organ damage – Internal and external bleeding

Tissue Damage leads to Hemorrhaging

• Hemorrhagic fever syndrome• late symptoms:

– toxic shock, hemorrhaging• Direct tissue damage

• liver, combined with massive viremia

• Disseminated intravascular coagulopathy

• Endothelial susceptibility• Subverts innate and adaptive

immune responses • Terminal stages

– diffuse bleeding, and hypotensive shock accounts for many Ebola virus fatalities

Diagnostic• Specialized laboratory test on

blood specimens for detection of – Antigens– Genes of the virus– Antibodies against the

virus• New techniques

– Non-invasive methods: saliva and urine samples

• Diagnosing• ELISA Assay• IgM ELISA• PCR Courtesy of:

http://www.ncbi.nlm.nih.gov

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.

Bio-Warfare• 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 - Russian Allies- Collaborative efforts in finding

a cure for Ebola- Decreased Fear- A cut of the profits

• Hazards of US Aid

- VECTOR removed from biowarfare threat list; however, 4 other weapons labs exist with no U.S. inspection

- 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 VirusEbola Virus– CDC classifies it as:

• Category A bioterrorism agent

– Sudden, severe onset of symptoms

– Believed to hide out in animals

– No approved vaccine or treatment

– Short incubation period• May kill victim before

transmitted to others (high death rate)

• Outbreaks seem to burn out quickly

Smallpox VirusSmallpox Virus– CDC classifies as

• Category A bioterrorism agent– Incubation period between

contraction and the first obvious symptoms of the disease is usu. 12-14 days

– Initially vague, flu-like symptoms, turn into severe symptoms (fever, severe pain, characteristic rash)

– Humans are the only natural host– Historic death rate of 1 in 3 – Vaccination in 1967

• Effective if administered up to 4 days after viral exposure and before rash appearance

– No effective treatment – 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

References 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 http://www.carnegie.org/reporter/04/preventing/index.html

7) Leroy, E., Fruit Bats a Reservoir for Ebola Virus. Indigo Base, IRD. November 2005. Retrieved 11/8/07 www.ird.fr/us/actualities/fiches/2005/fiche231.htm

8) World Health Organization. Ebola Haemorrhagic Fever. Retrieved 11/8/07

Refrences • 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. 438:575–57611) Pourrut, X, Kumulungui, B, Wittmann, T et al. The Natural History of Ebola Virus in Africa. Microbes and Infection. 2005.

7:1005–101412) 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

0022-53815) BMC Microbiology 2003 3:6 doi:10.1186/1471-2180-3-616) www.biomedcentral.com/1471-2180/3/6/figure/F3www.biosci.ohiou.edu/virology/Ebola/Dectec3.jpg(Courtesy of http://www.ncbi.nlm.nih.gov/ICTVdb/Images/Murphy/ebola_cell.htm17) World Health Organization• http://www.who.int/mediacentre/factsheets/fs103/en/• Provisional Revision: 200718) Leroy, Eric M., et al. Multibple Ebola Virus Transmission Events and Rapid Decline of Central African Wildlife. Science 303:

387 -389. 200419) Facts sheet: Community Health Administration• http://edcp.org/factsheets/ebola.html Journal of Virology

Thank you!