Herpesvirus Flashcards
1
Q
Structure of Herpes Viruses
- genome
- envelope?
- What is the tegument? what is in it?
A
- double stranded DNA w/ capsid
- present with gB-gN proteins
- region between the capsid and the environment that contains proteins
2
Q
Sequence of Transcription
- What proteins are synthesized early?
- What rises as these proteins are made?
- What proteins are synthesized late?
A
- DNA synthesis proteins
- DNA
- Virion proteins
3
Q
Productive Infection
- What happens first?
- Where does viral DNA go?
- What happens next?
- What is the final step?
A
- Virus fuses with cell via glycoproteins on cell surface receptors
- goes into nucleus in its capsid, then transcribed into mRNA and more DNA is made
- Proteins are made in the cytoplasm and come back into the nucleus to make the capsid;
- virus buds off cell
4
Q
Herpes Simplex Type 1
- Primary infection locations
- What kind of cells does it infect and kill?
- What does virus infect but not kill?
- What does it produce there?
- What happens in reactivation?
- What causes reactivation?
A
- cold sores, sore throat, fevery, encephalitis (rarely); less frequently found as genital infection
- Epithelial cells
- Sensory neurons
- Latency associated transcripts (LATs)
- virus travels back to epithelial cells, causing lesions and shedding
- Unknown
5
Q
HSV 1
- How much virus is being produced in latent infection? What are the symptoms
- Where does virus/viral DNA reside?
- What happens in recurrent infection?
- symptoms
A
- none, no symptoms
- sensory cells of trigeminal nerve ganglion
- virus replicates and travels down sensory nerve fiber to infect epithelial cells around the nose and mouth
- milder form of primary infection
6
Q
HSV2
- Primary infection
- Transmission
- Who gets it?
- Associated with what?
A
- vesicular eruptions on the genitalia
- sexual contact
- both sexes
- cervical carcinoma, less frequently found as herpes labialis (cold sores)
7
Q
HSV2
- How much virus is produced in latent virus?
- Where does viral DNA reside?
- Where does the recurrent infection occur?
- Symptoms
A
- none
- sensory cells of sacral ganglion
- same location in genital area
- milder form of primary infection
8
Q
HSV Infections
- What tends to cause encephalitis and meningitis?
- What are Whitlow’s nodules?
- What do Whitlow’s nodules look like?
A
1, reactivation infections
- nodules on hands caused by exposure to HSV at that point;
- bacterial infection
9
Q
Infections Assoc w/ HSVs
- 1 very common infection
- 2 common infections
- 3 rare/ very rare infections
A
- oral herpes- usually resolves
- genital herpes- usually resolves; ocular herpes (more commonly in elderly)- resolution; visual impairment
- neonatal herpes (development impairment, death); encephalitis (neuro impairment, death); disseminated herpes (resolution or death)
10
Q
Acyclovir
- Mechanism
- Why doesn’t it affect human cells?
- What does it do to duration of virus?
- What does it do to reactivation of virus?
A
- similar to GTP, is phosphorylated to acyclo GTP which is then put into extending DNA which then terminates the chain
- the first step is catalyzed by viral thymidine kinase, not found in human cells; inert in uninfected cells
- decreases duration
- prevents reactivation
11
Q
Acyclovir Resistance
- Who tends to be infected with resistant mutants?
- Why these pts?
- 2 mutations
- How do you treat these pts
A
- Immunocompromised Pts
- Mutations tend to attenuate virus, so healthy immune systems can still fight infection
- viral thymidine kinase (drug not phosphorylated to active form)
- viral polymerase (no longer efficiently binds the drug)
- improve immune system function
12
Q
TZP/Us
1. Mechanism of Action
A
- binds herpes virus helicase-primase; prevents unwinding
13
Q
Varicella Zoster
- Primary infection
- Transmission
- Seasonal?
A
- chicken pox; systemic infection resulting in generalized pruritic vesicular rash
- from one infected child to another
- seasonal epidemics during school year (when many children are together)
14
Q
Varicella: Clinical Features
- What happens first?
- Then what?
- Where does rash occur?
- What happens in healthy children?
- When is pt contagious?
A
- mild prodrome (fever, malaise) for 1-2 days
- successive crops of pruritic vesicles
- first on head, most concentrated on trunk
- mild infection
- From a few days before fever throughout rash;
15
Q
Varicella
- Where does virus replicate?
- What coincides with the contagious period?
A
- lymph nodes
2. secondary viremia; primary viremia occurs after viral replication in lymph node