Rabies & Measles & RSV Flashcards
What are viruses with non-segmented genomes?
1) Paramyxoviruses = measles, mumps, RSV, parainfluenza.
2) Rhabdoviruses = rabies, vesicular stomatitis virus (VSV).
3) Filoviruses = Ebola virus, Marburg virus
What are viruses with segmented genomes?
1) Bunyaviruse = hantavirus, La Crosse virus, Uukuniemi Bunyamwera virus.
2) Arenaviruses = lymphocytic choriomeningeitis virus (LCMV), Lassa fever virus
3) Orthomyxoviruses = influenza
Describe how - strand RNA viruses differ
They come from a number of virus families so there are differences in the details of replication however their overall replication strategies are similar.
What is RSV?
is a negative sense single stranded RNA virus.
- medium sized (around 150 nm) enveloped virus
-the genome is linear and approximately 15,000 nucleotides in length
- It is non-segmented which means that unlike influenza RSV cannot participate in the type of genetic reassortment and antigenic shifts responsible for large pandemics.
Describe the effects of RSV
Respiratory syncytial virus is a common respiratory infection that typically causes mild cold like symptoms but it can cause serious illness particularly in older adults and infants.
What is some history about measles
zoonotic origin evolved from rinderpest which infects cattle.
A precursor of measles began causing infections in humans in the 4th century BC or as late as after AD 500
It is an endemic disease (continually present in community and many people develop resistance) in populations not exposed to measles exposure to the new disease can be devastating.
Between 1855 and 2005 measles is estimated to have killed about 200 million people worldwide
How many people does the average person with measles infect?
18 people
What are the important aspects of paramyxoviruses?
-Enveloped, negative strand, non-segmented genomic RNA
- Upper respiratory tract infections
- 2 systematic diseases; measles and mumps
Describe paramyxoviruses?
Virions are enveloped and can be spherical or plemorphric and capable of producing filamentous virions.
The diameter is around 150 nm.
Genomes are linear around 15 kB in length
May also include HA and NA
What are characteristics of negative strand RNA viruses
- Enveloped ss RNA viruses the genomic RNA is (-) strand polarity so does not serve as mRNA unlike positive strand RNA viruses
-isolated virion RNA is NOT infectious - The genomic RNA Is present as an RNP (ribonucelomprotein with helical symmetry within the virion particle.
- Virions also contain a virus encoded enzyme, RNA dependent RNA polymerase aka transcriptase.
Viiron envelop derived from host cell membrane
contains many copies of 1 or 2 rarely 3 viral polypeptides (glycoproteins) embedded in the membrane and protruding outside of the particles a spikes.
These surface glycopreotines are responsible for viral interaction with cell surface receptors, they are also targets for the host antibody response.
In the measles virus case study what was the physical diagnosis?
cough, coryza (runny nose, nasal inflammation) conjunctivitis
Kopik Spots rash!
What is the incubation period of measles?
9-12 days before becoming infectious
What is the incubation period for rabies
30-100 days
Measles virus disease manifestation
Complications: otitis media, croup, bronchopneumonia, encephalitis, subacute sclerosis pan encephalitis
Paramyxoviruses disease manifestation types 1-4
Cold like symptoms, bronchitis croup
Pneumoniavirus disease manifestation
(RSV)
Bronchiolitis, pneumonia, febrile rhinitis,s pharyngitis, common cold
Who developed the measles vaccine?
Morris Hilleman
How is measles transmitted?
inhalation of large droplet aerosols
highly contagious
Risk factors for measles
adults and children can get it
immunocompromised persons have more serious outcomes
Distribution of virus
Ubiquitous
endemic from autumn to spring
Vaccines or antiviral drugs for measles?
Live attenuated vaccine
no antiviral drugs
What are the disease mechanisms of measles?
-Transmitted via respiratory secretions
-Infects epithelial cells of respiratory tract, spreads in lymphocytes and by viremia
- Replicates in conjunctivae respiratory tract, urinary tract, lymphatic system, blood vessel, central nervous system
-T cell response to virus infected capillary endothelial cells causes rash
-Cell mediated immunity is required to control infection
- Complications are due to immunopathogensis or viral mutants
Important facts about measles virus infections
Can access CNS and lead to a persistent infection
Mechanisms of measles virus induced immunosuppression
-Direct suppression of lymophcite proliferation via infection.
- Indirect suppression of lymmophcyte proliferation by measles virus infected cells
- soluble factors
-cell to cell contact
-Disruption of cytokine balance
-reduction of IL-12 IFNa/B
-induction of Th2 cytokines
-Disruption of dendritic cell function/antigen presentation.
True or False contracting measles can squash your body’s ability to remember and fight off previously experienced pathogens
True
What are examples of non segmented genomic RNA zoonotic viruses?
Rabies virus
Ebola virus
Segmented genomic RNA zoonotic viruses
Hantaviruses
Arenaviruses
How is rabies virus transmitted?
Reservoir: wild animals (makes it hard to eliminate)
Vectors: wild animals
unvaccinated dogs and cats
Bite of rabid animal virus in saliva or aerosols in caves harboring rabid bats
At risk or risk factors of rabies
animal handlers, vets,
those in countries with no pet vaccinations or quarantine
Vaccines or antiviral drugs for rabies?
-Vaccines for pets and wild animals
- Inactivated virus vaccine for at risk personnel post exposure prophylaxis
-No antiviral drugs
How many estimated deaths are caused by rabies?
20,000 per year worldwide
True or False: Taller people have more time before virus reaches brain than shorter people
True
