Transcript Hemorrhagic Fevers - Columbia University

Hemorrhagic Fevers
With a Concentration on
Filoviruses
Simon A Francis
Susanna Epstein
Medha Goyal
History
• Hemorrhagic Fevers
– Definition: a severe multi-system syndrome.
• Vascular System Damaged
• Body regulation Impaired
• Accompanied by hemorrhage
– Four families of viruses
• Arenaviruses (Junin Virus)
• Bunyaviruses (Nariovirus )
• Flaviviruses (ie. Yellow Fever)
• Filoviruses (Marburg & Ebola)
– CDC Classification: BSL-4 Agent
History
• Hemorrhagic Fevers (Continued)
– RNA viruses covered in a lipid coating
– Viruses are geographically restricted to areas
where host species live
– Humans are not natural reservoirs for these
viruses
History
• Filoviruses
– Marburg Virus
• A.K.A. (African Hemorrhagic Fever, Green Monkey Disease, Marburg
Fever)
• First outbreak (Marburg Germany, 1967)
• laboratory workers infected by monkeys
• Simultaneous outbreak in Hamburg, Germany and
Belgrade, Yugoslavia (now Serbia)
• 32 human cases
• 31 primary one generation of secondary transmission
• 23% of human mortality
• Overall Mortality 23%-25%
History
• Filoviruses (continued)
– Ebola Virus
• Named after a river in the Republic of Congo
(Formerly Zaire)
• First outbreak (Zaire 1967)
– 318 human cases
– 88% mortality
– Disease spread by close personal contact in hospital
setting (amplification)
• Fatal in humans and non-human primates
• Four subtypes (~80 nm in diameter)
– Ebola-Zaire(990-1086 nm in length ), Ebola-Sudan (9741063 nm in length), Ebola-Ivory Coast, Ebola-Reston
(disease in non-human primates 1026-1083 nm in length )
History
• Filoviruses (Continued)
– Ebola (Continued)
• Sudan international scientist arrived
– To late to deal with virulent epidemics
» Hospitals closed
» Infected patients quarantined
– Reconstructed data from survivors
Outbreaks
• Marburg
– Europe Outbreaks
• 1967
• Hamburg and Marburg, Germany and Belgrade, Yugoslavia
– Africa Outbreaks
• 1975
– Johannesburg, South Africa
– 3 died
• 1980
– Western Kenya
– 2 Died (Physician died in Nairobi)
• 1987
– Young man traveling extensively in Kenya
• 1999-2000
– Outbreak in Durba, Republic of Congo
– Cases linked to workers in a gold mine
Outbreaks
• Ebola (types named after location)
This diagram was adapted from a WHO publication accompanied by
the following note (edited): Phylogenic tree showing the
evolutionary relationship of Ebola viruses (courtesy of A.
Sanchez, Centers for Disease Control and Prevention [CDC];
derived from Georges-Courbet MC, Sanchez A, Lu CY, et al.
Isolation and phylogenetic characterization of Ebola viruses
causing different outbreaks in Gabon. Emerg Infect Dis
1997;3:59-62).
Year
Ebola subtype
Country
No. of human
cases
Percentage of
deaths
among cases
Situation
1976
Ebola-Zaire
Zaire [Democratic
Republic of the
Congo (DRC)]
318
88%
Occurred in
Yambuku and
surrounding
area. Disease
was spread by
close personal
contact and by
use of
contaminated
needles and
syringes in
hospitals/clinic
s. This
outbreak was
the first
recognition of
the disease.
1976
Ebola-Sudan
Sudan
284
53%
Occurred in Nzara,
Maridi and the
surrounding
area. Disease
was spread
mainly through
close personal
contact within
hospitals.
Many medical
care personnel
were infected.
1976
Ebola-Sudan
England
1
0%
Laboratory infection
by accidental
stick of
contaminated
needle.
1977
Ebola-Zaire
Zaire
1
100%
Noted retrospectively
in the village of
Tandala.
1979
Ebola-Sudan
Sudan
34
65%
Occurred in Nzara.
Recurrent outbreak
at the same site as
the 1976 Sudan
epidemic.
1989
Ebola-Reston
USA
0
0%
Ebola-Reston virus
was introduced into
quarantine facilities
in Virginia, Texas,
and Pennsylvania by
monkeys imported
from the Philippines.
Four humans
developed
antibodies to EbolaReston virus but did
not become ill.
1990
Ebola-Reston
USA
0
0%
Ebola-Reston virus
was introduced once
again into quarantine
facilities in Virginia,
and Texas by
monkeys imported
from the Philippines.
Four humans
developed
antibodies but did
not get sick.
1992
Ebola-Reston
Italy
0
0%
Ebola-Reston virus
was introduced into
quarantine facilities
in Sienna by
monkeys imported
from the same
export facility in the
Philippines that was
involved in the
episodes in the
United States. No
humans were
infected.
1994
Ebola-Zaire
Gabon
49
59%
Occurred in
Mékouka and other
gold-mining camps
deep in the rain
forest. Initially
thought to be yellow
fever; identified as
Ebola hemorrhagic
fever in 1995.
1994
Ebola-Ivory Coast
Ivory Coast
1
0%
Scientist became ill
after conducting an
autopsy on a wild
chimpanzee in the
Tai Forest. The
patient was treated
in Switzerland.
1995
Ebola-Zaire
Democratic
Republic of
the Congo (formerly
Zaire)
315
81%
Occurred in Kikwit
and surrounding
area. Traced to
index case-patient
who worked in forest
adjoining the city.
Epidemic spread
through families and
hospitals.
1996
Ebola-Zaire
Gabon
31
68%
Occurred in
Mayibout area. A
chimpanzee found
dead in the forest
was eaten by people
hunting for food.
Nineteen people who
were involved in the
butchery of the
animal became ill;
other cases occurred
in family members.
1996
Ebola-Zaire
Gabon
60
75%
Occurred in Booué
area with transport of
patients to Libreville.
Index case-patient
was a hunter who
lived in a forest
camp. Disease was
spread by close
contact with infected
persons. A dead
chimpanzee found in
the forest at the time
was determined to
be infected.
1996
Ebola-Zaire
South Africa
2
50%
A medical
professional traveled
from Gabon to
Johannesburg,
South Africa, after
having treated Ebola
virus-infected
patients and thus
having been
exposed to the virus.
He was hospitalized,
and a nurse who
took care of him
became infected and
died.
1996
Ebola-Reston
USA
0
0%
Ebola-Reston virus
was introduced into
a quarantine facility
in Texas by monkeys
imported from the
Philippines. No
human infections
were identified.
1996
Ebola-Reston
Philippines
0
0%
Ebola-Reston virus
was identified in a
monkey export
facility in the
Philippines. No
human infections
were identified.
20002001
EbolaSudan
Uganda
425
53%
Occurred in Gulu,
Masindi, and
Mbarara districts of
Uganda. The three
most important risks
associated with
Ebola virus infection
were attending
funerals of Ebola
hemorrhagic fever
case-patients,
having contact with
case-patients in
one's family, and
providing medical
care to Ebola casepatients without
using adequate
personal protective
measures.
20012002
Ebola-Zaire
Gabon and The
Republic of the
Congo
122
79%
Outbreak occurred
over the border of
Gabon and the
Republic of the
Congo. Additional
information is
currently available
on the WHO
website.
New York Times
• February 15, 2003
• World Briefing: Africa
• CONGO REPUBLIC: EBOLA TOLL REACHES 51 The
death toll from a suspected outbreak of the deadly Ebola
virus in Congo Republic has crept up to 51, and people
have begun fleeing into dense forest to escape what
some believe to be an evil spell. The authorities have
tried to impose tight restrictions on movement in the
hope of preventing the spread of the outbreak, the
second reported in little over a year in the country's
remote northwest. It is thought to have been caused by
the consumption of infected monkey meat. (Reuters)
Transmission
•
Ebola Virus
–
–
–
–
•
No carrier state (reservoir Unknown)
Researchers Hypothesize that it is Zoonotic
Unpopular theory that plant may be the reservoir of the virus
Human to Human Transmission through contact of contaminated
secretions.
Ebola-Reston
– Occurred in the U.S (Reston, VA)
– Occurred in African Green Monkeys
– Why only to non-human primates?
• Four scientist found to have antibody for the disease
– Circumstantial Evidence of airborne transmission
• Spread within and between rooms (national center for Infectious Diseases)
•
Marburg Virus
– Transmission from animal host unknown
– Human to Human (Close Contact and change of fluids highly suspect
source of transmission)
Reservoir
• Not known
• May be
– A rare species
– One that usually does not contact clinical host
– If contact is made the virus may not be easily
transmitted
• Hypothesize
– Bats
– Plants
Filoviruses General Facts
• Replication:
– Not fully understood. Created by budding of
the surface of their host cells (Susanna)
• Structure:
– Pleomorphic: Long sometimes branched
filament shaped like a “6”, “U” or a circle.
– Each Virion contains one molecule of single
stranded, negative sense RNA (Susanna)
• Symptoms of Ebola and Marburg (Medha)
INCUBATION & DEATH PERIODS
• Ebola Incubation at 2 – 21 Days
• Marburg Incubation: : 3-9 days
• VHF (in general) - Death Between 7 – 16
Days
• Ebola Death Ensues as Early as 2 Days
after expression of symptoms
Morphology and Structure
• Filamentous or Bacillus form
• Vary greatly in length (up to 14000 nm)
Mean Unit Length
Marburg- 860 nm
Ebola- 1200 nm
• Uniform diameter of 80 nm
Filovirus
Composed of:
• Ribonucleoprotein complex (nucleocapsid)
• Matrix
• Envelope studded with peplomers (10 nm long)
Filovirus Genome
•
•
•
•
Nonsegmented, negative-strand RNA
Filovirus Genome – 19 kb
7 Genes
Nucleotide and amino acid differences b/w
Marburg and Ebola – 55%
Ebola – 37 to 41%
• Overlaps
1 in Marburg genome –
VP30 to VP24
2 in Ebola genomeVP35 to VP40 & GP to VP30
• Glycoprotein Gene
Marburg- GP gene encodes 1 product
1 open reading frame (0)
Ebola- GP gene encodes 2 products
2 open reading frames (0 & -1)
connected by the insertion of 1 additional A
at a series of 7 U’s on the genomic RNA
• The 7 sequentially arranged genes are
transcribed into
Ebola - 8 major mRNAs
(7 structural proteins and 1 nonstructural protein)
Marburg – 7 major mRNAs
(7 structural proteins)
Filovirus Proteins
• Ebola and Marburg
encode 7 structural proteins
• Ebola
encodes 1 nonstructural protein
• Two Main Categories
Associated with the nucleocapsid
transcription and replication of viral genome
Associated with the envelope
assembly of virus
receptor binding and virus entry
• Ribonucleocapsid Proteins
1. Nucleoprotein (NP)
2. Viral Protein 35 (VP35)
3. Viral Protein 30 (VP30)
4. Polymerase L
Gene 1
Gene 2
Gene 5
Gene 7
• Matrix Proteins
5. Viral Protein 40 (VP40)
6. Viral Protein 24 (VP24)
Gene 3
Gene 6
• Membrane Protein
7. Glycoproteins (GP)
Gene 4
• Secreted Protein
8. Secretory Glycoprotein (sGP)
Gene 4
Nucleoprotein
• Primary structural protein associated with the
nucleocapsid
• Hydrophobic N-terminal half
Binds genomic RNA
• Hydrophilic C-terminal half
(Variable b/w Marburg and Ebola)
Interacts with matrix proteins
• VP30- Minor structural protein associated with the
nucleocapsid
• Polymerase L- Transcription and Replication
(largest and least abundant protein)
• VP35- Cofactor in transcription and Replication
(Cofactor in polymerase complex)
• VP40- Matrix protein
Virus assembly and budding
Forms hexamers when it contacts the plasma
membrane which confers added stability during
assemebly.
(most abundant protein)
• VP24- Minor Matrix Protein
Possibly uncoats virus during infection
Expression of Glycoprotein
• Transcriptional RNA Editing (occurs only in Ebola)
At a series of 7 U’s on the genomic RNA template
insert a non-template-coded adenosine
20% of GP mRNA is edited
GP with 680 amino acids
80% of GP mRNA is not edited
sGP with 370 amino acids
GP (Structural)
• Formation of GP1-GP2 Heterodimer
In the trans-Golgi, the precursor molecule (GP0) is post-translationally
cleaved by furin at yielding a heterodimer, (GP1-GP2)
Furin cleavage site (Arg-Arg-X-Arg/LYS-Arg)
(Marburg, cleavage site is more toward N-terminus)
Heterodimer is linked together by one disulfide bond, a cysteine bridge
• GP1 Molecule
C-terminus: hydrophilic, highly glycosylated
Sequences for receptor recognition and binding
N-terminus: hydrophobic
Connects GP1 to GP2 by a disulfide bond
• GP2 Molecule
Fusion peptide near near its N-terminus
Capable of inserting itself in plasma membranes
Believed to mediate the fusion of the host and virus membranes
• Functions of GP
Forms the Virion Peplomers (Surface Spikes)
Trimers of the GP1-GP2 Heterodimer,
probably assembled in the ER
Mediates viral entry
by receptor binding and membrane fusion
sGP (non-structural)
• Formation and Structure
Homodimer
Synthesized from GP mRNA using the conventional ORF
Produced from a precursor molecule cleaved by furin near the Cterminus, Precursor molecule  SGP and Delta Peptide
Homodimer is linked in anti-parallel orientation by 2 disulfide bonds
between the 1st and 6th cysteines on separate molecules
Virus Entry and Replication
in Host Cells
• Viral surface spikes recognize and bind surface receptors of host
• Virus enters cell via endocytosis
• Release of nucleocapsid into cytoplasm
• Transcription
viral RNA  polyadenylated, monocistronic mRNA
• Translation and buildup of viral proteins, primarily NP
• Budding and release of viruses
• Host Cell – dies
intracytoplasmic vesiculation, mitochondrial swelling,
organelle breakdown
Molecules mediating filovirus entry
Marburg
• Asialoglycoprotein Receptor
(Found exclusively in hepatocytes)
Recognizes glycoproteins displaying N-linked sugar
chains with terminal galactose residues
Ebola
• Integrins
N-glycosylated transmembrane cell surface receptors
Ebola and Marburg
• Human folate receptor-
Co-factor expressed on cell-surface
Reverse Transcription System
Volchkov et al. contructed 2 recombinant EBOV clones
1. pFL-EBOVe+
antigenomic cDNA clone with authentic editing site
2. pFL-EBOVeantigenomic cDNA clone with mutated editing site
Eliminated editing site using site-directed mutagenesis
Editing site in middle of GP gene AAAAAAA
EBOV polyadenylation signal ATTAAGAAAAAA
AAAAAAA  AAGAAGAA
Observations
1. Both pFL-EBOVe+ and pFL-EBOVeShowed typical filovirus structure
Possessed similar infectivity and virus production
2. Visible Cytopathic Effects
pFL-EBOVe+ : 4-6 days after infection
But there was still an intact monolayer at day 8
pFL-EBOVe- : 3-4 days after infection
5-6 days after infection, cell rounding was complete
3. Differences in expression of the GP gene
Wild Type – 1/5 GP, 4/5 sGP
pFL-EBOVe+ - 1/5 GP, 4/5 sGP
pFL-EBOVe- - no sGP expression,
increase in GP expression
The increase in GP expression by pFL-EBOVeno simultaneous increase in virus release
most of GP synthesized were immature precursors
-with sugar side chains high in mannose
-sensitive to treatment with endoglycosidase H
-GP transport was arrested in ER or early Golgi
Conclusions
• No Transcriptional RNA Editing
Over-expression of GP
Exhausts Cell Host Machinery
Eventual Cell Death
• So GP expression and cytotoxicity can be downregulated by virus through transcriptional RNA editing
and sGP expression
Pathogenesis of EBOV Infection
•
sGP
1. Inhibits early activation of neutrophils
-Binds to neutrophils via CD16b cell surface receptor
-CD16b activates neutrophils via lateral membrane interaction
with CR3
2. Adsorbs neutralizing antibodies
•
GP
1. Specific region of GP induces cytotoxic effects in endothelial cells
-Rapid release of vasoactive agents from infected cells
-Induces cell rounding and detachment from extracellular matices
-Increases cell membrane premeability
2. Proteolytic activation of GP0 precursor via cleavage
-EBO-Z GP cleaved by furin
-Prerequisite for fusion between viral envelope and host
cell membrane
-Enables virus to replicate in host systematic infection
3. Two sequences contribute to evasion of host immunity
-Possible immunosuppressive sequence in GP2
molecule
-Amino acid sequence at amino terminus suppresses
lymphocyte mitogen-stimulated proliferation in vitro
• Destruction of the Immune System
1. Infects mononuclear phagocytes and fibroblastic reticular system
(associated with lymph nodes)
- Failure of early T-cell activation
-Disrupts antigen trafficking and cytokine production
-Extensive apoptosis of blood leukocytes
-Lymphopenia (reduction in lymphocyte #) and severe damage to
lymphoid tissue
2. Macrophages and circulating monocytes help transmit virus to other
tissues
3. VP35 protein – Type 1 IFN Antagonist
-Combats the host interferon response
possibly enhancing the replicative ability of the virus
Key to Surviving Ebola
French National Institute- Early Immune Response
1996 – Two large outbreaks in Gabon
Compared immune responses
• Survived
-IgG response against virus’s protein coat early on
-Cleared circulating antigen
-Activated cytotoxic T-cells
• Died
-No IgG response
-Barely detectable levels of IgM
Pathology of Marburg and Ebola
EARLY STAGE:
• Striking lesions usually in liver, spleen and kidney
• Necrosis prominent in liver, lymph tissue, and spleen
• little inflammatory response
• Viral particles invade phagocytic cells
Pathology of Marburg and Ebola
LATE STAGE:
• Liver and spleen become enlarged with excess blood
• Hemorrhage in the gastrointestinal tract, pleural,
pericardial and peritoneal spaces and into the renal
tubules with deposition of fibrin
• Abnormalities in coagulation parameters suggest that
disseminated intravascular coagulation is a terminal
event.
• There is usually also profound leukopenia in association
with bacteremia.
Example of cervical tissues with
severely enlarged and hemorrhagic
lymph nodes from a laboratory Rhesus
monkey.
Differential Diagnosis
• High Fever
• Severe prostration
• Diffuse
maculopapular rash
• Bleeding
•
•
•
•
Myalgia
Bradychardia
Desquamation
Loss of apetite
OTHER DIAGNOSTIC CRITERIA
•
•
•
•
•
•
Coagulation Studies
Serologic Study
Leukopenia (Low White Blood Cell Count)
Thrombocytopenia (Low Platelet Count)
Low Electrolytes
lymphopenia followed by neutrophilia
DIAGNOSTIC TESTS FOR EBOLA
•
•
•
•
•
•
ELISA (Enzyme-Linked Immunosorbent
Assay)
Can’t differentiate Ebola strains with electron
microscope
Indirect fluorescent antibody test (IFAT)
Western blot analysis
Radioimmunoprecipitation assay
skin biopsies
ELISA
•Purified, inactivated filovirus antigens pre-coated onto an
ELISA plate
•If the patient has filovirus, serum contains antibodies to the
filovirus antigens, and those antibodies will bind to the
antigens on the plate. Test can be specific to IgM or IgG.
•Anti-human Ig coupled to Chromogen enzyme binds IgM or IgG.
•Color change indicates positive test
Clinical Course
• 2-21 Day incubation time
• 50-90% Mortality
• Variability of clinical presentations complicate early
detection and management
• Non-specific prodrome typically lasts < 1 week
• 10 to 12 days after the onset of disease, the sustained
fever may break, with improvement and eventual
recovery of the patient.
• 1-2 weeks after onset of symptoms: Death often
preceded by hemorrhagic diathesis, shock, multi-organ
system failure
A Word From the Experts…
On Scene Footage…
Transmission
• Direct contact with the blood, secretions, organs or semen of
infected persons:
– study of risk factors among family members in Kikwit. 27 surviving
members were interviewed. Determined that those who had direct
contact or who were exposed during late hospital phase were at very
high risk. Those who had no physical contact with infected members
remained uninfected.
– Transmission through semen occurs up to 80 days after clinical
recovery.
• Handling ill or dead infected people or chimpanzees
• Health care workers have frequently been infected while attending
patients- Kikwit outbreak.
• Neonatal
• Droplets or small filovirus particle aerosols confirmed in alveoli of
monkeys during Reston outbreak.
Current Therapy
• Essentially supportive and directed toward ensuring
adequate tissue delivery of oxygen, nutritional support,
and hydration.
• Hemorrhage is managed by replacement of blood,
platelets, and clotting factors
• Passive transfer of human antibodies has remained
inconclusive in its benefit to Marburg and Ebola.
• Ribavirin is a synthetic nucleoside analog that is of use
in treating Lassa fever and Arenavirus, but there is
unfortunately no benefit in Ebola virus infection.
Prophylaxis
• Study shows:
– hyperimmune globulin effective in protecting experimentally
infected baboons if administered at the same time as virus, the
treatment was ineffective if delayed for 3 days. Hyperimmune
globulin should, however, be considered for prophylactic use in
laboratory or nosocomial accidents although humans may
require antibodies with higher specificity.
• Inconclusive evidence- whether whole blood transfusion
from convalescent patients are effective.
– Kikwit epidemic- 8 convalescent patients were given blood
transfusions. 7/8 survived. Administered late, patients had better
prognosis for survival, lack of controls.
Comorbidity: Pregnancy
• Illness from Ebola is generally more severe in
pregnant women, with more serious
hemorrhagic and neurologic complications
• Case fatality rate of pregnant women was 95.5%
versus 77% in nonpregnant infected persons
• Spontaneous abortion is frequent, with fetal
losses reported to be as high as 23%–66%
• All infants born to mothers with EHF ultimately
died within 19 days of delivery
Potential Vaccines
• Dutch biotechnology company, Crucell, is to collaborate with the US
National Institute of Allergy and Infectious Diseases (NIAID) to
develop the first vaccine against the Ebola virus.
– The new vaccine uses DNA encoding three Ebola glycoproteins and
one nucleoprotein, followed by a boost with a replication-defective
adenovirus expressing Ebola antigens (Nature 408, 605; 2000). It is the
first vaccine to generate protective immunity against Ebola in nonhuman primates.
• Scientists at the US Army Medical Research Institute of Infectious
Diseases report a simple method for generating Ebola virus–like
particles. (JAMA March 2002)
• A researcher has discovered a link between HIV and Ebola virus:
Both viruses use the same method to spread through the human
body. Aids Alert - 01-Feb-2002
Vaccine Contd.
• Reverse genetics vs Forward genetics
– genetics that is concerned with genetic
material whose nucleotide sequence is known
-analyzes its contribution to the phenotype of
the organism by varying the nucleotide
sequence
-observe the results of such variation in the
living organism, in living cells, or in vitro on
macromolecules
Ebola from scratch
• In January 2002 scientists reported making Ebola using
"reverse genetics".
– They took the virus's genome plus pieces of DNA coding for the
key viral proteins and added them to cells. These proteins then
kick start the replication process.
• Good News: DNA is more stable and easily manipulated.
Method provides in-depth understanding of viral
mechanism of action that may lead to a vaccine/cure.
• Bad News: People acquire ability to synthesize Ebola
Weaponization
• History of Ebola Weaponization
– Soko Asafra head of Aum Shinrikyo cult 1992
– Russians
THE APRIL of 1988 USTINOV INCIDENT
• Ustinov conducted basic research on the Marbur
Virus studying its potential as a weapon
• Long term goal: To see if Marburg Virus could be
loaded into special biological warheads on the
Soviets MIRV missiles.
• MIRV has multiple warheads which are directed
at different targets
• They at the time where designed to be loaded
with strategic/operational smallpox virus, black
death, and anthrax.
• Variant U was born
Weaponization
• Fall 1991 Marburg Variant U becomes a
strategic operational Bioweapon
• Russians loaded virus into 10 separate coneshaped warheads on the MIRV.
– Cooling system inside each warhead keeps the virus
alive during heat of atmosphere.
– Biowarheads parachuted over the target city
• Certain altitude they break apart
• Each warhead burst a spray of more than a hundred oval
bomblets each the size of a small cantaloupe
• Cantaloupes fly and then split again in an overlapping
manner releasing a haze of bio-particles that quickly become
invisible.
Challenges
• Finding the Reservoir
• Need to know more about Transmission
– From animal to man
– Ways of putting it into food
• Aerosolization
– Possible
– Stable Base needed (difficult)
Why Use Filoviruses as Bioweapon
• Filoviruses (Ebola in particular)
– Rates of fatality
– Deaths
• Terror of dying
• Ignorance of the general public
– Think that they can die by being in same room with
person
• Much not known by general physicians and
scientist
Genetic Engineering
• At Marburg and Ebola conference talk about creation of genetically
engineered Ebola virus
– Volchkov of Claude Bernard University in France and Institute for Virology in
Marburg
– Powerful Molecular tool to analyze how these viruses cause disease.
• Constructed DNA Molecule (Complimentary Nucleotide sequence to Ebola)
• Introduced complementary sequence in cultured cell lines with genes coding
for 4 key Ebola proteins
• Cells proceeded to make new Ebola RNA
• Resulting in fully infectious when transferred to new cell lines
• Military Definition: The creation of genetically altered viruses and/or
bacteria to enhance their power as weapons
• Reasons for use in Filoviruses
– To make the virus stronger
– Mixtures
• Ebolapox
– Smallpox is an extremely lethal virus highly contagious in the air.
OPERATIONAL EFFECTIVENESS OF
EBOLAPOX
Produces a form of smallpox called blackpox
 Blackpox is the most severe type of Smallpox.
 In BLACKPOX infection the skin does not develop
blisters
 Instead the skin becomes dark all over
 Blood vessels leak, resulting in severe internal
hemorrhaging
 Therefore, EBOLAPOX would not only provide the
Terrorist with the hemorrhages and high mortality
rate of the Ebola virus, but in addition as an added
bonus would incorporate into its operational
effectiveness the incredibly high contagiousness of
Smallpox

Ways to protect against Ebola
• Government
– Biosafety Department
– CDC & other agencies
– Debriefing of experts
– Public health education
• Weaponeers
• Public policy and preventative measures
(Medha)
PREVENTING VHF EPIDEMIC
•
•
•
•
•
Hospitalization and Isolation of
Patients
Quarantine Areas if Necessary
Protective Measures (Gloves, Gowns,
Face Shields, Masks, Eye Protection)
Disinfect Bedding, Utensils, Excreta
(Heat or Chemicals)
Burn Used Articles
Isolation Criteria
Decision-making for isolation is based upon 4 main factors:
1. Potential harm to life
2. Potential harm to critical systems
3. Potential harm to property
4.Topography & meteorological considerations
Isolation Precautions
• Direct Contact with infected blood, body fluids to
be avoided.
• Airborne transmission rare, but cannot be
conclusively excluded- negative pressure room
and HEPA respirator.
• Laboratory Precautions- BSL 4
• Personal Protective Equipment
• Post-Mortem Practices (Kikwit
And Uganda)
Prevention and Control
• Reservoir remains unknown
• Clarify roles of GP, sGP, and
other viral proteins.
• Multivalent vaccine needed
(4 strains of Ebola)
• Health infrastructures strengthened
especially in Africa
• Surveillance improved to prevent potential
spread of an epidemic.