2013-02-15 VIR Herpes

Question 1

Herpesvirus Nucleic acid set-up? Virion structure? How does it multiply? Examples?

Answer 1

NA = single, linear dsDNA vir = icosahedral enveloped w/ tegument REPLICATION: EXAMPLES: HSV, varicela-zoster, CMV, EBV

Question 2

What is a viral tegument?

Answer 2

is a cluster of proteins that lines the space between the envelope and nucleocapsid of all herpesviruses.[1][2] The tegument generally contains proteins that aid in viral DNA replication and evasion of the immune response

Question 3

What is the subclassification of herpesviruses? Tost range? Tropism? Example?

Answer 3

Alpha-wide host range, latency in neurons, e.g. HSV-1&2 Beta-narrow host range, latency in monocytes, e.g. CMV Gamma-narrow host range, latency in lymphocytes, e.g. EBV

Question 4

How do herpesviruses replicate?

Answer 4

1. fusion 2. DNA—>nucleus 3. mRNA goes out to cytosol, is translated and then those early prots go BACK to the nuc to act as transcription factors 4. enveloped temporarily from nucleus 5. get permanent envelope from the Golgi 6. delivered as vesicle to cell surface

Question 5

What is the time course of herpesviridae infections?

Answer 5

latency: causes neither destruction nor transformation; allows the virus to maintain lifelong infection of the host

Question 6

What theories exist about how latent viruses evade immune system?

Answer 6

1. LATs (latency-assoc. transcripts) and LANAs (latency-assoc. nuclear Abs) 2. epidemiological study showing HSV-2 pts shed q3-5d

Question 7

How does acyclovir work?

Answer 7

acyclovir (a.k.a. acycloguanosine) is a nucleoside analog: cannot be phosphorylated by thymidine kinase (unique version in primates); has higher affinity for vDNA polymerase—>causes chain differentiation

Question 8

Compare the lesion patter in small pox vs. chicken pox

Answer 8

chicken pox more central smallpox more on limbs

Question 9

HSV-1&2

Family = ?

Epidem = ?

Trans = ?

Incubation = ?

Pathogen w/ s/sx = ?

Dx = ?

Prevention = ?

Tx = ?

Answer 9

Family = Alphaherpesviruses (HHV-1 & HHV-2)

Epidem = ubiquitous

Trans = saliva, vaginal secretions and lesion fluids—>eyes/breaks in the skin—>axonal transport to achieve latency

Incubation = ~7 days (CDC)

Pathogen w/ s/sx = Cold sores, ocular infections, (HSV-1) genital sores (HSV-2) and encephalitis (deadly, caused by both 1&2)

Dx = isolate and culture (causes CPE), ELISA, PCR of CSF, IgM/serology

Prevention = no vaccine

Tx = great drugs (nucleoside analogs) including: acyclovir, valacyclovir, famcilovir, pencilovir, adenosine arabinoside, iododeoxyuridine, trifluridine

Question 10

Chicken Pox

Family = ?

Epidem = ?

Trans = ?

Incubation = ?

Pathogen w/ s/sx = ?

Dx = ?

Prevention = ?

Tx = ?

Answer 10

Family = herpesviruses —> alpha-herpesviruses —> varicella zoster (HHV-3)

Epidem = common in 4-10 y/o’s in non-vacc countries

Trans = aerosol or direct contact

Incubation = 2-3 weeks

Pathogen w/ s/sx = viremia —> prodrome w/ fever & malaise —> rash

IN ADULTS: worse; tx w/ ACV; re-activation causes shingles—> deratomal presentation VERY PAINFUL

Dx = clinically

Prevention = vaccines: pedi (oka strain = Varivax), adult (Zostavax = same strain, just 1/14 strength))

Tx = can try ACV in severe cases; usually just palliative

Question 11

CMV

Family = ?

Epidem = ?

Trans = ?

Incubation = ?

Pathogen w/ s/sx = ?

Dx = ?

Prevention = ?

Tx = ?

Answer 11

Family = Herpesvirus—>betaherpesvirus (HHV-5)

Epidem = ubiquitous

Trans = blood, tissue, body secretions (URINE DIAPERS)

Incubation = ?slow? (see Dx)

Pathogen w/ s/sx = latency in leukocytes (powerful T-cell evasion strategy); usually subclinical, but also: Most common cause of congenital abnormalities in U.S.; Pneumonia, retinitis, esp in immunocompromized (esp pre-HAART)

Dx = have to PCR b/c grows very slowly

Prevention = wash hands, warn pregnant women

Tx = gancilovir, Vitravene (direct to retina)

Question 12

EBV

Family = ?

Epidem = ?

Trans = ?

Incubation = ?

Pathogen w/ s/sx = ?

Dx = ?

Prevention = ?

Tx = ?

Answer 12

Family = herpesviruses—>gammaherpesviruses (HHV8)

Epidem = ubiq. (>90% U.S. adults positive)

Trans = kissing/saliva

Incubation = ~(2-?)4(-6? slides conflict) wks

Pathogen w/ s/sx = infects oral epithel—>blood—>B-cells—>immorts B-cells—>T-cells clear things up which cause “mono” sx in teens/adults (mild/asymp in kids)

—Mono sx: lymphadenopathy, hepatosplenomegaly

—in immunocomp: Burkitt’s lymphoma and nasophar. carcinoma I.E. TUMOR VIRUS

Dx =

Prevention = no vaccine

Tx = no anti-virals

Question 13

HHV‐6

Answer 13

roseola infantum/ exanthem subitum.
• Benign rash with high fever. Rarely encephalitis.
• >90% worldwide.
• Approx 1% have HHV‐6 integration into germline

Assoc’d with MS/CFS*/epilepsy

*chronic fatigue synd

Question 14

HHV-7

Answer 14

closely related to HHV‐6.
• “No treatment for HHV‐7 infec4on exists, but no clinical situation where such treatment would be useful has yet been discovered.”
“A virus that is looking for a dz.”

Question 15

HHV-8

Answer 15

Kaposi’s Sarcoma Herpes Virus (KSHV)

• tumor virus that causes opportunistic infection in HIV pts not on HAART
• common in sexually-trans HIV
• No vaccine
• Tx w/ excision

Question 16

B-virus

Answer 16

zoonosis that sometimes infects zookeepers, etc.

From Rhesus macaques

Rare but serious encephalitis

tx w/ acyclovir or immune serum

Question 17

Herpesvirus

Nucleic acid set-up?

Virion structure?

How does it multiply?

Examples?

Answer 17

NA = single, linear dsDNA

vir = icosahedral enveloped

REPLICATION

1. fusion
2. DNA—>nucleus
3. mRNA goes out to cytosol, is translated and then those early prots go BACK to the nuc to act as transcription factors
4. enveloped temporarily from nucleus
5. get permanent envelope from the Golgi
6. delivered as vesicle to cell surface

EXAMPLES

HSV, varicela-zoster, CMV, EBV