Various viruses Flashcards
What type of genome does polio virus encode?
(+) ssRNA
What is polio virus’s tissue tropism?
It infects GI epithelial cells, but may spread to muscles and neurons
How is polio Virus transmitted?
Fecal Oral route
What does poliovirus cause in most people?
95% asymptomatic acute GI infection
1% paralytic infection of motor neurons
What is the reservoir of polio virus?
ONLY humans - why it is able to be erradicated (if we didn’t fuck up in pakistan whoops)
How does the Polio virus recognize, enter, and uncoat at the GI epithelial cells?
- It Binds a cell-surface receptor
- virion becomes hydrophobic –creating pore through cell membrane
- capsid pulled open by receptors to release genome into cytosol
- UNCOATS at plasma membrane
What is the next step after uncoating for the poliovirus?
- Host ribosome translates genome into polyprotein w/ a protease at the end
- protease cuts polyprotein into smaller proteins, the last of which is RDRP
In RNA (+) viruses, in reference to RDRP levels, when does translation occur and when does replication occur?
translation occurs when RDRP is scarce
replication occurs later when RDRP is abundant
Where does replication occur for the poliovirus?
In a vesicle (check what kind)
How does the polio virus egress?
Through cell lysis (This is common for enteroviruses)
When does the switch from mRNA synthesis to genome RNA synthesis occur?
When enough capsid proteins accumulate
What kind of viruses encode RDRP?
ALL RNA viruses
What kind of viruses always package RDRP?
(-) ssRNA viruses and dsRNA viruses
What is the treatment and prevention of polio virus?
Treatment:
-control symptoms - breathing support
Prevention:
-Vaccine, sanitation
How would you classify a rotavirus?
- Icosahedral
- dsRNA segmented
- naked
What symptoms does an infection with rotavirus cause?
Severe gastroenteritis
-profuse watery diarrhea, dehydration, malabsorption
Who does rotavirus primarily infect?
Children
What is the seasonal occurence of rotavirus?
It has a peak incidence in the winter
Where does transcription and translation occur for the rotavirus? (and all other RNA viruses except influenza)
In the cytoplasm
How does the rotavirus egress?
Through exocytosis (from vesicles from the ER) or cell lysis
Where do rotaviruses mature?
In the gut lumen and then go on to infect other enterocytes or are cleared by diarrhea
How would you treat a patient with rotavirus?
Oral rehydration
Is there a vaccine for rotavirus?
Yes - live attenuated rotarix and rotateq
How would you classify influenza?
Helical, (-)ssRNA segmented, enveloped
Where does transcription and translation of influenza occur?
In the nucleus- it travels there via a nuclear localization signal
How does the influenza virus egress?
Budding - N antigen releases virions via hemaglutinin from sialic acid on cell surface
How are influenza virions shed?
Through respiratory droplets - coughs and sneezes
What are some treatments for influenza and what do these do?
Tamiflu (oseltamimivir) & relenza (zanamivir) - block the release of virions
Amantadine targets host interacting proteins
What type of strains are in a flu vaccine?
It is trivalent consisting of two A strains and one B
If different subtypes of influenza combine to form a new influenza subtype what is this called?
Antigenic shift (genetic shuffling) PANDEMIC
If a mutation occurs, creating a different form of the same strain, what is this called?
Antigenic Drift
How would you classify HIV?
Icosahedral, (+)RNA TWO copies, enveloped
RETROVIRUS
How would you tell the difference between an infection with the flu or HIV?
In HIV there will be sores of the viscera, thrush (candida) and lymphadenopathy
When is a person classified as having AIDS?
When their T cell count is below 200
When is a person classified as having AIDs with an advanced HIV infection?
When their T cell count is below 50
What are the 7 stages of HIV infection?
- Transmission
- Primary HIV infection - acute phase
- Seroconversion
- Latent period
- Early symptomatic HIV infection
- AIDs
- Advanced AIDs
What is the HIV cell tropism and host range?
CD4+ T cells and macrophages
ONLY humans can be infected
Name some opportunistic infections in patients with AIDs?
- P. carinii pneumonia
- esophageal candidiassi
- karposis sarcoma
- M avium
- TB
- Cytomegalovirus
- bacterial pnuemonia
How does the HIV virus penetrate the cell?
fusion - it has an envelope
What is the next 3 steps of HIV pathogenesis after fusion?
- Reverse Transcriptase converts RNA+ to dsDNA
- –cytoplasm - Integrase integrates dsDNA into host genome, 3.host RNA Pol2 transcribes mRNA from integrated genome
Where does HIV maturation occur?
Outside of the cell membrane - HIV protease cleaves the capsid proteins and forms the final trapezoidal shape
How would you diagnose HIV infection?
- antibodies to gp120
- PCR for viral load
- T cell count
What are some ways to avoid risk of infection with HIV?
Public health is very important, use condoms, avoid unsterilized needles
What is used to treat HIV?
ART - combination drugs targeting
RT, integrase, protease, CCR5 antagonists
What is occurring during clinical latency of HIV?
There are more T cells than virus present
Which DNA viruses encode their own DNA Polymerase?
Adenovirus, Herpesvirus (Large DNA viruses)
Which viruses are genetically more stable RNA or DNA viruses?
DNA viruses (RDRP has higher fidelity -error rate is 1 in 10^5 as opposed to 1 in 10^3, also proofreads)
What are the clinical symptoms of an infection with adenovirus?
Pharyngoconjunctival fever, laryngitis and cough, pnuemonia
Others:
keratoconjunctivitis, gastroenteritis, acute hemorrhagic cystitis
How is adenovirus transmitted?
Aerosol or fecal oral (nonchlorinated swimming pools)
Describe the 5 steps of adenovirus pathogenesis from entry until uncoating
- Spikes bind to cell surface receptor
- enters via endocytosis
- endosome acidification causes spikes to lyse the vesicle
- capsid travels to nuclear membrane
- genome uncoats through nuclear pore
where is HSV-1 latent?
tri gem ganglia
where is HSV-2 latent
in neurons
where is varicella-zooster virus latent?
dorsal root ganglion
where is epstein barr latent?
B cells in bone marrow
where is HHV 6&7 latent (roseola)?
CD4 cels
what antiviral can be used to treat HSV1,2 and varicella-zooster
acyclovir
what can epstein barr virus reactivate as in immunocompromised people?
lymphoma
is herpes virus restrictive to humans? what about herpes simplex virus?
HV is human restrictive
HSV is not human restrictive
does herpes use host or viral DNA pol. for replication?
viral DNA polymerase
where does herpes virus get its envelope from?
host golgi membrane
what is the definition of latency?
genome is present in cell but infectious virions are absent
list 3 complications of zooster virus
bell’s palsy-facial paralysis
postherpetic neuralgia-acute pain
retinitis-virus infects optic nerve, can permently go blind
what diagnosis method would you use to distinguish between a HSV-1 and HSV-2 infection?
PCR and serology
list 4 complications of chicken pox
hepatitis
encephalitis
pneumonitis
bacterial infection- getting staph aureus at the site of infection
what are the symptoms of the prodome stage of herpes zooster?
burning, itching, tingling
how is zooster lesions contagious?
can spread the virus to children who have not yet been infected with chicken pox
list 3 complications of zooster virus
bell’s palsy
postherpetic neuralgia-acute pain
retinitis-virus infects optic nerve, can permently go blind
what is herpes zoster ophthalmicus which can occur in the 30% of zooster outbreaks that infect the face
any tissue in the eye can be infected during HZO
virus can destroy retina-lead to blindness
what vaccines are there for the ZVZ?
varicella vaccine people age 1-50
zooster vaccine for people over 50
what two cells does epstein barr virus infect?
oral epithelial cells and B cells in tonsils
how do you diagnose epstein barr virus?
serology for herrophile antibodies
why would you diagnose for epstein barr virus if there is no treatment?
to differentiate between EBV and strep throat which you would give medication for
how do you distinguish from EBV and CMV?
CMV has a rash and NO sore throat
how do you screen for CMV and who is screened?
you can diagnose with serology, culture and PCR but it is really only done on pregnant women
how is EBV and HHV6&7 transmitted?
through salvia
what characterizes HHV6&7 (roseola)?
3 day illness of fever, followed by faint rash on trunk
what is the peak age of roseola infection?
7-13 months
what is the treatment for roseola infantum?
NONE
is the roseola rash contageous?
NO. the salvia is
Where does transcription and replication occur in adenovirus and other DNA viruses?
Nucleus
Does host or viral RNA polymerase perform transcription in DNA viruses?
ALWAYS HOST RNA pol II
In adenovirus what molecule performs replication?
viral DNA polymerase
What are the stages of gene expression in adenovirus?
controlled by host/viral transcription factors:
- immediate early=viral TFs
- early=Viral DNA Polymerase
- late=capsid for packaging virions
How does adenovirus egress?
Cell lysis
Which viruses egress by cell lysis?
- Poliovirus
- Rotavirus
- Adenovirus
Is there treatment for adenovirus infections?
Yes - cidovfovir but only used for most dire cases since it is a nephrotoxin
Which viruses of these listed do NOT have a vaccine available? Poliovirus Rotavirus Influenza Virus HIV Adenovirus Human Papilloma Virus (HPV) Herpes Virus HSV-1 HSV-2 Varicella-Zoster (VZV) Epstein-Barr Virus (EBV) Cytomegalovirus (CMV) Roseola (HHV6 & HHV7) Hepatitis A Hepatistis B Hepatitis C
- HIV
- EBV
- Cytomegalovirus
- Hepatitis C
According to Moffat, what is the most commonly diagnosed STD in the US?
Papilloma virus
What symptoms does infection with papilloma virus cause?
common warts, plantar warts, genital warts
What are the malignancies associated with papilloma virus and how are these caused?
- head and neck cancer
- cervical cancer
- penile cancer
-oncogene activation - E6 and E7
What is the tropism for the papillomavirus?
Differentiated Epithelial cells
Where does the initial phase of the papilloma virus infection occur?
In the basal epithelium
What molecule performs DNA synthesis for the papilloma virus?
Host DNA polymerase - small DNA virus
How would you diagnose an infection with HPV?
DNA testing for the different types
What are the different treatment methods for an infection with HPV?
cryotherapy, chemical ablation, colposcopy, oncotherapy
What are the two vaccines available for HPV composed of?
VLP - virus like particles - empty capsids
-abs are created to full 3D structure
How long does an infection with herpes virus last for?
fooooooreeeeeeevvvvver - lifelong
What is the host range for herpes virus?
ONLY humans
What does latency mean?
Genome is present in a cell, but infectious virions are absent
What is the tropism for :
- HSV-1
- VSV
- HCMV
- EBV
- HSV-1, VSV - neurons
- HCMV - Hemapoetic stem cells
- EBV -B cells
Describe the steps of pathogenesis of herpes virus
- Attachment
- Fusion or endocytosis
- Uncoating at nuclear pore
- Host RNA Pol2 transcribes mRNA
- Travels to the cytosol
- translation occurs in phases in cytosol
- genome replicated by Viral DNA Polymerase, 8. capsid assembles in nucleus and enclsoes tegument and genome
- Virion buds through nuclear membrane to gain envelope!
- virion egresses via exocytosis (cell not harmed by virus)
