Emergeing viruses Filoviruses (Marburg and Ebola) Arenaviruses (LASSA and related viruses), Bunyaviruses (Sin Nombre Virus) Flashcards
Describe Filoviruses
Virus: Marburg virus
Disease: Hemorrhagic fever
Virus: Ebola virus
Disease: hemmorrhagic fever
Filovirus Transmission
Contact with infected monkeys or tissues secretions or body fluids
Contact with infected humans
Accidental injection, contaminated syringes
Filovirus at risk or risk factors
-Monkey handlers
-Health care workers attending sick
Filovirus distribution of virus
-Endemic in monkeys in Africa
No seasonal incidence
Filovirus vaccines or antiviral drugs
None
Filovirus disease mechanisms
-Acquired from monkeys or infected humans
-Virus replication causes necrosis in liver, spleen, lymph nodes, and lungs.
-Hemorrhage causes edema and shock
What are unique and shared features of filoviruses compared to other non-segmented negative strand RNA viruses?
-Ebola and Marburg viruses cause severe hemorrhagic disease (unique).
- Negative strand RNA, single strand genome; genes arranged linearly on genome (shared)
Enveloped virions (shared)
-Morphology of viroions = U shaped, 6 shaped, or circular shape 80 nm in diameter, up to 14,000 nm long (unique)
-Synthesis of both secreted and membrane bound surface glycoprotein (unique)
- Novel viral protein VP24 = inhibits the induction of the host anti-viral genes by blocking interferon signaling (unique)
Describe the structure of Ebola virus
The interaction between nucleoprotein subunits is not as rigid as other viruses such as tobacco mosaic virus so Ebola virus often shows a wavy structure
True or False: Naked RNA is not enough to cause infection
True
U shape advantageous true or false?
True, according to evolution
What are the symptoms of Ebola virus infection?
-Fever greater than 38.6 C or 101.5 F
-Severe headache
-Muscle pain
-Weakness
-Diarrhea
-Vomiting
-Abdominal (stomach) pain
- Unexplained hemorrhage (bleeding or bruising) (viruses destroy tissue integrity, blood vessels can’t get blood).
-
Ebola virus health outcomes
Symptoms may appear anywhere from 2-21 days after exposure to ebola average is 8-10 days
Recovery depends on good supportive clinical care and patient immune response
people who recover from ebola develop antibodies that last for at least 10 years.
Transmission of Ebola virus
-Spread through direct contact (via broken skin or mucuous membranes in eyes, nose, or mouth)
-blood or body fluids (including urine, saliva, sweat, feces, vomit, breast milk, semen) of a person who is sick with Ebola
- Objects (needles/syringes) that have been contaminated with the virus.
-Infected animals
-Virus not spread through the air or by water or in general by food; in Africa may be spread as a result of handling bushmeat.
-No evidence that mosquitos or other insects can transmit Ebola virus; only mammals (human, bats, monkeys, and apes) have so far been infected with the Ebola virus.
-Healthcare providers caring for Ebola patients and family/friends in close contact with Ebola patients are at the highest risk of getting sick since they may come in contact with infected bloody/body fluids of patients.
True or False, reassortment of RNA segments of 2 different strains of influenza produce new isolates of influenza which can lead to new viruses with the potential to cause pandemics.
True
Hantavirus transmission
Rodents are the host to the virus
Virus is present in feces, urine, and saliva
If it becomes airborne it can be inhaled by humans and result in infection.
Can also enter the body through open wounds and rodent bites.
What happens in the early stages of hantavirus?
Fever
Muscle aches
Fatigue
Nausea
Abdominal pain
What happens in late stage hantavirus
Hantavirus pulmonary syndrome
coughing
shortness of breath
fluid filling in the lungs
40% mortality rate
New world Hantaviruses (Americas)
Lead to Hantavirus pulmonary syndrome (HPS)
Old World Hantavirus known in Europe and Asia
Can cause hemmorhaic fever with renal syndrome (HFRS)
What is the most important hantavirus in the US that can cause HPS?
Sin Nombre virus spread by the deer mouse
Hantavirus is part of what virus family?
Buyavirus family
Associated with hemorrhagic fever and renal syndrome
In 1993, Sin Nomrbre virus was associated with acute respiratory illness in southwestern US
> 50% mortality rate
first report of acute hantavirus associated illness in America
Hantavirus in other parts of the world are not associated with severe respiratory illness
Primarily spread through deer mice
Likely from rat excrement
Bunyaviruses transmission
Arthropod bites
Rodent Excretea
Bunyavirus at risk or risk factors
people in the area of vector (campers)
Bunyavirus distribution of virus
depends on distribution of vector on rodents
disease is more common in summer
Bunyavirus vaccine or antiviral drugs
none
Bunyavirus disease mechanisms
Transmitted by arthropod bite or rodent excreta
Primary viremia then secondary viremia leads to virus spread to target tissues including CNS various organs and vascular endothelium
Antibody is essential for controlling viremia
Characteristics of hantaviruses
No arthropod vector established which is unique
Rodent hosts
Transmission by aeroslozation of rodent excrement
What is the clinical presentation of hantavirus pulmonary syndrome?
Most frequent:
- fever
-myalgia
-nausea/vomiting
- cough
Other:
-dizziness
-arthalgia
-shortness of breath
Rare:
Rhinorrhea
Sore throat
Sin Nombre Virus Summary
Family: Bunyaviridae
Transmission: Vertebrate hosts
no arthropod vectors
Viral Particles: spherical 80-120 nm
Structural proteins: glycoproteins: G1, G2, nucleoprotein: N
Genome: ss RNA, tri segmented, negative polarity
Arenavirus: Lymphocytic Choriomeningeitis virus
Disease: Febrile, flu like myalgia; meningitis
Arenavirus: Lassa Virus
Lassa fever: severe systemic illness, increased vascular permeability shock
Arenavirus: Junin virus
Argentine hemorrhagic fever: similar to Lassa fever but more extensive bleeding
Arenavirus: Machupo virus
Bolivian hemorrhagic fever
Arenavirus transmission
Contact with infected rodents or their secretions or body fluids
Arenavirus at risk or risk factors
Lymphocytic chiorimentigis virus: contact with pet hamsters, areas with rodent infestation.
Other arena viruses: habitat of rodents
Arenavirus distribution of virus
Lymphocytic choriomeningitis virus: hamsters and house mice in Europe, Americas, Australia, possibly Asia
Other arena viruses: Africa, South America, US,
No seasonal incidence
Arenavirus vaccines or antiviral drugs
No vaccines
antiviral drug ribavirin
Arenavirus disease mechanisms
Transmitted from persistently infected rodents
Persistent infection of rodents caused by neonatal infection and induction of immune tolerance
Viruses infect macrophages and release mediators of cell and vascular damage
Tissue destruction caused by T cell immunopathology
More arena virus facts
Latin for Sandy
Enveloped virus or pleomorphic
single stranded genome divided into 2 RNA segments
Two genes on each segment encoding a total of 5 proteins
Lassa fever pathogenesis comes from?
T cells
Key Points: Negative Strand RNA Viruses
General Features:
All viruses are enveloped with genomic RNA in a helical RNP
Virions carry viral transcriptase (RNA dependent RNA polymerase)
Transcription template is an RNP complex
Some virion glycoproteins have special features/activities
Cause many different types of disease
Viruses with non-segmented genomes (paramyxoviruses, rhabodo viruses, filoviruses)
Synthesize multiple mRNA from one genomic RNA
Viruses with segmented genomes (bunyaviruses, arena viruses, orthomyoxiviruses)
Potential for segment re assortment disease implications
Influenza has many unique features during virus replication which takes place in nucleus.
Which of the following statements about Sin Nombre virus (a hantavirus) is also true for rabies virus?
A) It carries out mRNA synthesis in the cytoplasm of infected cells?
B) It can be transmitted by exposure to rodent excreta
C) It carries a segmented genome in its virion particle
D) There is no approved vaccine against the virus
E) None of the above
A) It carries out mRNA synthesis in the cytoplasm of infected cells?
Which of the following properties is NOT shared by measles virus and Ebola virus
A) Encode their own RNA dependent RNA polymerase
B) Utilize mRNA editing during their infectious cycle
C) Assemble virus particles in the cytoplasm of infected cells
D) Transmission by blood borne route
E) Enveloped various
D) Transmission by blood borne route
