Negative strand RNA viruses Flashcards by G G

Paramyxoviruses

measles virus
mumps virus
respiratory syncytial virus (RSV)
parainfluenza viruses

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Rhabdoviruses

Species: rabies virus

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Orthomyxoviruses

(Family = Orthomyxoviridae) Chapter 36

Species: influenza viruses A, B and C

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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
minus stranded

Paramyxoviruses

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Paramyxovirus replication
Virus brings in _________ which transcribes minus RNA
into _________ (full length and ______)
Replication is cytoplasmic

Paramyxovirus replication
Virus brings in RNA polymerase which transcribes minus RNA
into plus RNAs (full length and mRNAs)
Replication is cytoplasmic

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Measles virus

(~16000 nt –strand RNA genome)
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)

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Measles virus (~16000 nt ______strand RNA genome)
__________ - envelope glycoproteins
attachment proteins (bind virus to host cells)
__________ - causes membranes to fuse together
role in viral entry into cells
expression on infected cells causes cell-cell fusion
Giant cells (syncytia)

Measles virus (~16000 nt –strand RNA genome)
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)

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Measles (Rubeola)
caused by measles virus
• enters body through
\_\_\_\_\_\_
• extremely\_\_\_\_\_\_

caused by measles virus
• enters body through
respiratory tract
• extremely contagious

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Measles (Rubeola)
skin involvement (partly, inflammation due to______)
humoral and ________ modulate outcome

skin involvement (partly, inflammation due to host response)
humoral and cellular immune responses modulate outcome

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Koplik spots

Measles (Lesions of oral cavity)

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Measles Signs

WTF is Coryza

􀀂3 C􀀁s􀀃 = cough, coryza,
conjunctivitis
Also morbilliform appearance
(rash = exanthem)
Coryza 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.

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WTF is Coryza and WTF is it associated with?

Measles
Coryza 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.

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Measles Complications

complications
– Pneumonia (giant cell pneumonitis)
– Bacterial superinfections of middle ear
and lung
– pneumococci, staphylococci, and
meningococci
• subacute sclerosing panencephalitis
– rare progressive degeneration of central
nervous system caused by a type of
measles virus
• treatment, prevention, and control
– symptomatic/supportive therapy
– attenuated measles vaccine
• MMR vaccine (measles, mumps,
rubella)
• 􀀁Live􀀂 Measles vaccine - 1993

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Pneumonia (giant cell pneumonitis)
– Bacterial superinfections of middle ear
and lung
– pneumococci, staphylococci, and
meningococci

Complications of measles

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subacute sclerosing panencephalitis

rare progressive degeneration of central
nervous system caused by a type of
measles virus

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Measles Treatment

treatment, prevention, and control
– symptomatic/supportive therapy
– attenuated measles vaccine
• MMR vaccine (measles, mumps,
rubella)
• 􀀁Live􀀂 Measles vaccine - 1993

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Mumps

caused by mumps
virus
– Paramyxovirus
pleomorphic,
enveloped virus
– helical nucleocapsid
– negative strand RNA
(~15,000 nt)

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caused by mumps
virus
– Paramyxovirus
pleomorphic,
enveloped virus
– helical nucleocapsid
– negative strand RNA
(~15,000 nt)

Mumps

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Swelling of parotid (salivary) glands

Prescott

Mumbs

clinical manifestations
– develop 16-18 days after infection
– fever, and swelling and tenderness of salivary glands
– complications include meningitis and orchitis
(inflammation of testis)

Mumps

Mumps Complications

Meningitis, orchitis (inflammation of the testis)

Maybe associated with Juvenile Diabetes

Mumps

Respiratory syncytial virus

minus stranded RNA
genome = one segment of RNA
enveloped

Respiratory syncytial virus
\_\_\_\_\_\_\_\_ binds host cells
(instead of a hemagglutinin)
\_\_\_\_\_\_\_\_ - causes membrane fusion
syncytia formation
virus enter respiratory \_\_\_\_\_\_\_, then spreads downward
along the \_\_\_\_\_\_\_\_\_\_ mucosa
no clinically significant spread to distant sites
\_\_\_\_\_\_ of epithelial cells
infiltration of lymphocytes
\_\_\_\_ mucous production

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

considered to be most dangerous respiratory infections | in young children

Respiratory syncytial virus (RSV)

Respiratory syncytial virus (RSV) clinical manifestations – acute onset of fever, cough, rhinitis, and nasal congestion – often progresses quickly to severe ______ and pneumonia • __________ - bronchiole obstruction that can lead to ________ failure host response may account for most serious

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

transmitted by: – 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

minus stranded RNA genome = one segment of RNA (~12,000 bases in length) enveloped, bullet shaped virus replication is entirely cytoplasmic

Skunks, racoon, bats, foxes

Rabies

``` incubation can be up to 12 months after virus enters body depends on size of inoculum location of bite face bite has shorter incubation Negri ```

Rabies

Negri bodies

masses of nucleocapsids in cytoplasm seen in brain tissue of 70-90% of infected humans

Rabies pathogenesis

``` Replication in muscle enter peripheral NS Ascent via sensory fibers replication in dorsal ganglia acsend spinal cord Facks app brain spinal cord cerebellum, Decends to eyes skin, slivary glands. ```

clinical manifestations – 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

Rabies

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 for Rabies.

Orthomyxoviruses | Enveloped or No?

Genus: Influenzavirus - influenza virus A, B and C minus stranded RNA enveloped

8 segments of RNA | 7 segments of RNA

8 segments of RNA (for influenza viruses A and B) | 7 segments of RNA (for influenza virus C)

􀀂cap-snatching􀀃 -

uses 5􀀁 end of host mRNA to prime viral mRNA synthesis

Random packaging

of the 8 segments (11 segments packaged per virion)

Surface spikes (peplomers) ________ (HA) attachment to host cell surface (prior to entry) binds to _______ on epithelial cell surface promotes membrane fusion (viral-cellular) binds/aggregates RBCs elicits protective neutralizing antibody response

Surface spikes (peplomers) hemagglutinin (HA) 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

neuraminidase (NA)

release of virus from envelope | cleaves sialic acid (NA has enzymatic activity)

Typical flu symptoms (fever, headache, muscle aches, malaise) due to ________

Typical flu symptoms (fever, headache, muscle aches, malaise) due to interferon induction

Treat with _______ _______ (A strain only); ______ (A and B) –inactivated virus vaccine

Treat with amantidine, rimantidine (A strain only); ribavirin (A and B) –inactivated virus vaccine

Antigenic shift Antigenic shifts in influenza virus are caused by __________ of viral _______ fragments during a ______ infection by two different _____viruses

Antigenic shifts in influenza virus are caused by reassortment of viral genomic fragments during a mixed infection by two different influenza viruses

``` Antigenic drift Changes in influenza virus surface proteins (hemagglutinin and neuraminidase) due to _________that occur during viral ______ is called antigenic drift. ```

Changes in influenza virus surface proteins (hemagglutinin and neuraminidase) due to point mutations that occur during viral replication is called antigenic drift.

Antigenic shifts in influenza virus are caused | by reassortment of viral genomic fragments

Human and Duck Flu is picked up by a pig, Antigenic shift occurs and the a new strain is made that can still infect hue-mons.

1918 flu pandemic: “spanish influenza”

1918 flu pandemic: “spanish influenza” killed 50 million world-wide victims usually young and previously healthy

Likely killed via a “_______” in victims with _____ immune systems unchecked _______ loop between ______ and cellular response result: too many immune system cells activated in an single space àtissue damage

Spanish Flu Likely killed via a “cytokine storm” in victims with strong immune systems unchecked positive feedback loop between cytokines and cellular response result: too many immune system cells activated in an single space àtissue damage