Major RNA Viruses Flashcards
What are the 5 general properties that apply to RNA viruses?
- Enveloped/non-enveloped
- capsid symmetry
- nucleic acid (ss or ds)
- +/- sense, ambisense
- replication location (?)
What is + sense RNA?
same RNA reading as host
What is - sense RNA?
needs RNA polymerase
What classification system is used to classify viruses?
Baltimore classification based on mRNA synthesis
Which RNA virus is double stranded?
Reoviridae
Which RNA viruses are nonenveloped?
Picornaviridae, Caliciviridaem Reoviridae
Where do most RNA viruses replicate? exception?
cytoplasm
Othomyxoviridae, Retroviridae
What class is a dsRNA?
Class III
What class is a (+)ssRNA?
Class IV
What class is a (-)ssRNA?
Class V
What class is ssRNA-RT?
Class VI
Describe the characteristics of picornaviridae?
+ssRNA
Nonenveloped
Icosahdral
resistant to pH 3-9
Where does the picornaviridae replicate?
cytoplasm
How is the picornaviridae classified?
Class IV
What are 3 genus for picornaviridae?
Enterovirus
Rhinovirus
Hepatovirus
What species are included in Enterovirus?
Poliovirus (1-3)
Coxsackie A (1-24)
Coxsackie B (1-6)
Enterovirus (68-71)
How are most Enteroviruses transmitted?
fecal oral
What cells are infected by the poliovirus?
oropharyngeal
intestinal mucosa
What are the clinical manifestations of poliovirus?
90-95% remain subclinical 5-8% flu-like symptoms 1-2% associated with major manifestations: meningitis encephalitis paralytic poliomyelitis
What are common viruses responsible for meningitis?
enterovirus coxsackie A&B echovirus Arbovirus HIV HSV-2
What cells are involved in paralytic poliomyelitis?
cells of the anterior horn - results in flaccid paralysis
medulla - paralysis of the diaphragm»_space;>death
What are the 3 types of paralytic polio?
spinal polio (paralytic) bulbar polio (muscle weakness) bulbospinal polio
How would you diagnose poliovirus?
isolation of virus from stool
CSF (definitive)
How would you treat polio?
no specific treatment > supportive
- pain and muscle spasm control
- orthopedic support to prevent contracture, deformities and fracture
How do you prevent polio?
Vaccine
OPV (Oral Polio vaccine)
IPV (Inactivated Polio Vaccine)
What are the advantages and disadvantages of OPV?
OPV Good: -oral, easily administered -lifelong immunity - no boosters necessary Bad: - risk of vaccine-associated polio -can't be administered to immunocompromised patients
What are the advantages and disadvantages of IPV?
IPV Good: - no risk of vaccine associated polio -safe for immunocompromised patients -easier to store and transport
Bad:
Booster needed
Injection
Large dose required
How is Coxsackievirus transmitted?
fecal-oral
How would you treat or prevent Coxsackievirus?
no vaccine or treatment
List 5 diseases due to Coxsackievirus A.
A9, A16 - hand, foot and mouth disease Aseptic meningitis (summer and fall) Herpangia A24 - acute hemorrhagic conjunctivitis A7 - poliomyelitis-like symptoms
List 4 diseases due to Coxsackievirus B.
Pleurodynia - “Devil’s grip”
*****Myocarditis (leading cause) and pericarditis
B2, B5 - hand, foot and mouth
B4 - juvenile diabetes (IDDM)
What are the clinical manifestations of hand, foot and mouth disease?
vesicular rash on hands, feet, mouth and tongue
mild fever
What are the clinical manifestations of Herpangina (Coxsackie A)?
fever
sort throat
anorexia
vomiting
vesicular ulcerating lesions on soft palate and uvula
What are the clinical manifestations of Conjunctivitis (Coxsackie A)?
eye pain followed by redness
teary painful eyes
swelling
light sensitivity
**highly contagious
What are the clinical manifestations of Pleurodynia (Coxsackie B)?
Acute onset of fever
unilateral low thoracic chest pain
“Devil’s Grip”
Males may have testicular pain.
How is Rhinovirus transmitted?
contact with respiratory secretions
What are the symptoms of Rhinovirus?
- runny nose
- common cold
**infections are localized to the nose
How is the hepatovirus transmitted?
fecal-oral
What is the characteristic of Hepatitis A?
+ssRNA
nonenveloped
icosohedral
What are the symptoms of Hepatitis A?
sudden fever
jaundice (self-limiting)
How do you prevent Hepatitis A?
Vaccine
-recommended for at-risk groups
What system does Hepatitis A infect?
intestinal epithelial cells
-spreads to liver
What are the characteristics of Caliciviridae?
\+ssRNA Nonenveloped icosahedral resistant to heat and detergents can be inactivated by acid (pH 3 99% inactivation)
How are most Caliciviridae transmitted?
fecal-oral (Norovirus, Sapovirus)
How do most Caliciviridae manifest?
gastrointestinal
- diarrhea
- vomiting
What is norovirus associated with?
contaminated water supplies and food
- potluck meals
- outbreaks on cruise ships
How would you diagnose norovirus?
virus isolated from stool and vomit
What are the symptoms of norovirus?
acute gastroenteritis 12-24 hours after ingestion of food
How do you prevent Norovirus?
good hygeine
How is Hepatitis E transmitted?
fecal-oral
What is Hepatitis E associated with?
- E for Epidemic hepatitis
- contaminated water supply
- high mortality for fetus and mother
What are the characteristic of Reoviridae (respiratory enteric orphan)?
- *dsRNA
- nonenveloped
- icodahedral
How is Rotovirus transmitted?
fecal-oral
(possibly respiratory)
- usually seasonally
- ubiquitous
Describe Rotavirus A and B.
Rota (wheel/spokes)
A - most common (90%) - infantile diarrhea with vomiting and fever
B - Adult onset of severe diarrhea (epidemic in Asia)
Describe the characteristics of Flaviviridae.
(+) ssRNA
Enveloped
What are two genus of Flaviviridae?
Flavivirus (Dengue virus)
Hepatitis C
How is Dengue virus transmitted?
Aedes aegypti (mosquito)
How does Dengue fever manifest with the 1st encounter? 2nd?
1st
- fever within 4-7 days post exposure
- severe headache
- severe joint and muscle pain
- nausea and vomiting
- rash, maculopapular
2nd Dengue hemorrhagic fever
- symptoms to classic dengue
- gingival and nasal bleeding
- increased menstrual flow
- GI bleeding
- hematuria
How is Dengue diagnosed?
ELISA serology (IgM, IgG) and antigens
tourniquet test
How do you manage Dengue virus?
-self-limiting
-control fever with antipyretics (avoid aspirin)
- use insect repellent
-no antiviral treatment
(no vaccine)
How is Hepatitis C transmitted?
blood
What damage is seen in the chronic state of HepC?
cirrhosis
end-stage liver disease
hepatocellular carcinoma
What is a symptom of HepC?
jaundice
What is the most common way Hep C is transmitted?
IV drug use (60%)
sex (15%)
Describe the characteristics of Togaviridae.
(+) ssRNA
Enveloped
icosohedral
enveloped “toga”
What two genus of Togaviridae?
Rubivirus (rubella)
Alphavirus (arboviruses)
How is Rubella virus transmitted?
contact with respiratory droplets
What are the symptoms in up to 70% of people infected with rubella?
asymptomatic
What are the clinical manifestations of rubella?
maculopapular rash - begins on face and spreads to trunk, then extremities
- rash fades after a few days
- occipital and post auricular lymphadenopathy
How do you prevent rubella?
MMR vaccine (12-18 months and dose 2 at 36 months)
Describe the consequences of Rubella during pregnancy?
During the viremic stage, the virus can cross the placenta.
Since Rubella can cross the placenta it can lead to congenital abnormalities, premature delivery and spontaneous abortion.
What infections are vertically transmitted?
TORCH
Toxoplasma gondii
Other infections (enterovirus, VZV, P-B19, HIV, Bacteria)
Rubella
CMV
HSV-2
Describe the characteristics of Filoviridae.
(-) ssRNA
enveloped
helical
What viruses are included in Filoviridae?
Ebola virus
Marburg virus
Cuevavirus (2011 Spain)
What are members of Filoviridae associated with?
hemorrhagic fever
(Ebola, Marburg)
*Dengue also can lead to hemorrhagic fever but is not part of this group
What are the signs and symptoms of Filoviridae?
Early: muscle aches, fever, vomiting, red eyes, skin rash
Acute: bleeding, skin hemorrhage
What are treatments for Filoviridae?
- NO FDA approved vaccine
- IV fluids and electrolytes
- maintain ventilation and perfusion
- manage infections
*antibodies may last up to 10 years
What are the characteristics of Orthomyxoviridae?
(-) ssRNA
enveloped (glycoproteins, antigenic variation)
segmented
-causes endemic and pandemic respiratory infections
Why is the characteristic of segmentation so important?
opportunity to mutate
mix gene segments
What are the three types of influenza and host?
Influenza A - humans, birds, swine (everything)
Influenza B - humans
Influenza C - mainly humans
Describe the structure of influenza and how it assists in entry of RNA into the host.
- Hemoglutinens (HA) attach to sialic acid receptor found on respiratory epithelial cells of host.
- The neuraminadase (NA) cleaves the sialic acid receptor and virus enters cell.
Matrix protein 2 (M2)- through envelope
Matrix protein 1 (M1)- on inside attached to ribonuclear protein
- After entry, the whole virus is inside.
- M2 will allow an H ion to enter the virion and cause dissociation of M1 and . ribonuclear protein.
- H ion drops the pH and the envelope breaks.
- (-) ssRNA is released.
- Complementary copy made and then translated.
Which influenza type can undergo antigenic shift?
Influenza type A
Which influenza type can underdo antigenic drift?
All types
Influenza A, B, C
What is antigenic shift?
- substitution of gene segments with segments from another influenza virus (reassortment)
- only seen in type A
- pandemics
- less common
What is antigenic drift?
- small, constant point mutation
- gradual changed in aa composition
- minor antigenic change
- epidemics
- all three types
- annual vaccination
How is influenza named?
Nomenclature system: Host origin Geographic location Strain number Year of isolation hemaglutinin and neuroaminidase subtypes
ex) A/California/7/2009 (H1N1)
How is Influenza transmitted?
person to person
direct contact
aerosol droplets
*infects respiratory epithelial cells
What is the incubation time for influenza?
1-4 days
What structure in Influenza is targeted by drugs?
M2 - matrix protein 2
neuroaminadase
What are the clinical manifestations of influenza?
fever headache chills muscle aches general fatigue runny nose (as fever declines) coughing (as fever declines)
Complications: Bronchitis, Pneumonia
What are treatments for influenza?
Zanamivir (Relenza) - targets neuroaminadase (A & B)
Oseltamivir (Tamiflu) - targets neuroaminadase (A & B)
Amantidine (target M2) - no longer recommended due to resistance
What is the recommendation for flu vaccine? method of delivery
yearly
flu shot - whole inactivated virus
Flumist - live attenuated
What are the characteristics of Paramyxoviridae
(-) ssRNA
enveloped
Matrix protein
G protein - mediates attachment to host cells
Fusion Protein (F) nfection of adjacent cells
What are two subfamilies of Paramyxoviridae?
ParamyxoviriNae
Pneumovirinae
What are two genus from the subfamily paramyxovirinae?
Rubulavirus (Mumps)
Morbilivirus (Measles)
How are mumps transmitted?
respiratory
Where does the mump virus replicate?
nasopharynx
What are the symptoms of mumps?
nonspecific myalgia
headache
parotitis (30-40%)
What are some complications of mumps?
orchitis (20-50) in post pubescent males
CNS involvement (15%)
pancreatitis (2-5%)
death
How would you prevent mumps?
MMR vaccine
How are measles transmitted?
respiratory droplets
nasal secretions
When are the measles highly contagious?
during prodromal period
What are the clinical signs of measles?
cough coryza (rhinitis) conjunctivitis (3Cs) Koplic spots high fever (40 C) generalized maculopapular rash
What are complications of measles?
diarrhea otitis media pneumonia encephalitis death
How would you prevent measles?
MMR vaccine
** major cause of vaccine-preventable death in chldren
How is RSV transmitted?
droplets
fingers
What is the most common cause of LRI in infants and kids?
RSV
