Paramyxo Viruses Flashcards
Species measles virus mumps virus respiratory syncytial virus (RSV) parainfluenza viruses
Paramyxoviruses (Family = Paramyxoviridae)
Paramyxoviruses
Rhabdoviruses
Orthomyxoviruses
Negative strand RNA viruses
Species: rabies virus
Rhabdoviruses
Species: influenza viruses A, B and C
Orthomyxoviruses
Helical nucleocapsid
Pleomorphic envelope (variable shape)
Hemagglutinin (measles virus) on envelope binds sialic acid on cell surface glycoproteins measles virus binds CD46 protein present on most cells
Paramyxoviruses
- Virus brings in RNA polymerase which transcribes minus RNA
into plus RNAs (full length and mRNAs)
2.Replication is cytoplasmic
Paramyxovirus replication
hemagglutinins - envelope glycoproteins attachment proteins (bind virus to host cells)
F protein - causes membranes to fuse together
role in viral entry into cells
expression on infected cells causes cell-cell fusion
Giant cells (syncytia)
Measles virus
t/f: All paramyxoviruses can induce syncytia formation
true
• caused by measles virus
• enters body through
respiratory tract
• extremely contagious
skin involvement (partly, inflammation due to host response) humoral and cellular immune responses modulate outcome
Measles (Rubeola)
Kroplik Spots
characteristic lesions of oral cavity
Measles (Rubeola)
is a word describing the symptoms of a head cold. It describes the inflammation of the mucous membranes lining the nasal cavity which usually gives rise to the symptoms of nasal congestion and loss of smell, among other symptoms.
Coryza
– Pneumonia (giant cell pneumonitis)
– Bacterial superinfections of middle ear
and lung – pneumococci, staphylococci, and
meningococci
complications of Measles (Rubeola)
– rare progressive degeneration of central
nervous system caused by a type of measles virus
subacute sclerosing panencephalitis
– symptomatic/supportive therapy
– attenuated measles vaccine
• MMR vaccine (measles, mumps,
rubella) • Live Measles vaccine - 1993
treatment, prevention, and control of Measles (Rubeola)
– Paramyxovirus
pleomorphic,
enveloped virus – helical nucleocapsid – negative strand RNA
Mumps
– develop 16-18 days after infection
– fever, and swelling and tenderness of salivary glands
– complications include meningitis and orchitis
(inflammation of testis)
clinical manifestations of MUMPS
– live, attenuated vaccine (MMR)
MUMPS vaccine
minus stranded RNA
genome = one segment of RNA
enveloped
G protein binds host cells (instead of a hemagglutinin)
F protein - causes membrane fusion
syncytia formation
virus enter respiratory epithelial cells, then spreads downward
along the respiratory mucosa
no clinically significant spread to distant sites
- necrosis of epithelial cells
- infiltration of lymphocytes
- increased mucous production
Respiratory Synctial Virus
- considered to be most dangerous respiratory infections in young children
- spread by hand contact and respiratory secretions
• clinical manifestations
– acute onset of fever, cough, rhinitis, and nasal congestion
– often progresses quickly to severe bronchiolitis and
pneumonia
• bronchiolitis - bronchiole obstruction that can lead to respiratory failure
host response may account for most serious symptoms
Respiratory syncytial virus (RSV)
How is Respiratory syncytial virus (RSV) tested?
– rapid immunologic tests
– negative strand RNA virus
– highly neurotropic
Rabies
– bites of infected animals
– aerosols in caves where bats roost
– contamination of scratches, abrasions, open wounds, or mucous membranes with saliva of infected animals
Rabies Transmission
minus stranded RNA
genome = one segment of RNA
enveloped, bullet shaped virus replication is entirely cytoplasmic
Rabies virus
_____, _____, ____, ___ are four animals common associated with tranmitting the rabies virus.
skunk
fox,
bat
raccoon
incubation can be up to 12 months after virus enters body
depends on size of inoculum
location of bite
face bite has shorter incubation
Rabies virus manifestations
______ ____ ascends via the sensory fibers and spreads among the nervous system.
rabies virus
masses of nucleocapsids in cytoplasm seen in brain tissue of 70-90% of infected humans
negri bodies
– begin 2 to 16 weeks after exposure
– pain or paresthesia at wound site, anxiety, irritability, depression, fatigue, loss of appetite, fever, and sensitivity to light and sound
– Hydrophobia: contractions of muscles involved in
swallowing (sometimes sight of water elicits this)
– quickly progresses to paralysis – death results from destruction of regions of brain that
regulate breathing
Clincal manifestations of Rabies Virus
– Passive administration of antibody (antiserum or immunoglobulin) (human rabies immune globulin = HRIG
collected from immunized persons)
– postexposure vaccination
– preexposure vaccination of individuals with high risk of exposure, dogs, and cats
Treatment, prevention and control of Rabies virus
Genus: Influenzavirus - influenza virus A, B and C
minus stranded RNA
enveloped
Orthomyxoviruses
8 segments of RNA (for influenza viruses _ and _ )
A and B
7 segments of RNA (for influenza virus _)
C
uses 5 end of host mRNA to prime viral mRNA synthesis
Cap snatching
attachment to host cell surface (prior to entry)
binds to sialic acid on epithelial cell surface
promotes membrane fusion (viral-cellular)
binds/aggregates RBCs
elicits protective neutralizing antibody
response
Surface Spikes (peplomers)
Hemagglutinin (HA)
release of virus from envelope cleaves sialic acid (NA has enzymatic activity)
neuraminidase (NA)
Typical flu symptoms (fever, headache, muscle aches, malaise) due to ____ ____ q
interferon induction
–Treat with amantidine, rimantidine (A strain only); ribavirin (A and B)
–inactivated virus vaccine
Influenza treatments
Changes in influenza virus surface proteins (hemagglutinin and neuraminidase) due to point mutations that occur during viral replication is called ____ _____.
antigenic drift.
_____ _____ in influenza virus are caused by reassortment of viral genomic fragments during a mixed infection by two different influenza viruses
Antigenic shifts
Antigenic shifts in influenza virus are caused by ________ of viral genomic fragments
reassortment
_____ play an important role as a “mixing vessel” for influenza viruses from humans, birds, and pigs. This is because pigs can become infected by these different influenza viruses.
Pigs
killed 50 million world-wide
victims usually young and previously healthy
Likely killed via a “cytokine storm” in victims with strong immune system
unchecked positive feedback loop between cytokines and cellular response result: too many immune system cells activated in an single space à tissue damage
1918 flu pandemic: “spanish influenza”
genome recovered in 1997 from victim in permafrost grave in Alaska
Sequencing showed the virus originated in birds and mutated to be infectious in human
H1N1 Virus
