Virology I

Question 1

Physico-chemical properties of herpes family (4)

type of genome, structure

Answer 1

1. dsDNA
2. icosahedral nucleocapsid
3. presence of an envelope. important for binding to host cell.
4. presence of tegument (matrix btw envelope and nucleocapsid). loaded w viral factors

Question 2

Alpha herpes HSV 1 and 2: epi and transmission

Answer 2

HSV-1: saliva. primary infection in childhood. 80-90% of people.
HSV-2: sex. 20-25% of sexually active adults.

Question 3

Primary infection with HSV-1: symptoms

Answer 3

1. gingivostomatiitis (lesions in mouth)- seen in kids
   pharyngitis or tonsilitis in adults.
2. herpetic whitlow (pustular lesion of the skin on the hand or finger. especially common in medical professionals. wear gloves when touching people’s sores)
   Rare (but serious):
3. keratoconjunctivitis: corneal lesions that can cause blindness (2nd cause of corneal blindness in US after trauma)
4. encephalitis- most common cause of sporadic viral encephalitis. untreated has 70% mortality rate. occurs in primary infection or in reactivation. diagnose w/MRI. also see fever, headache, and AMS

Question 4

Primary infection: HSV-2

Answer 4

genital lesions. painful vesicular lesions in genitals and anal region. Or, no symptoms.

Question 5

Neonatal herpes

Answer 5

contact w lesions in birth canal. preventable w C-section. can cause encephalitis and disseminated infection, or local lesions.

Question 6

HSV 1 and 2: persistent infections

Answer 6

infections taken up into nerves- travel to cell body. oral route: goes to trigeminal ganglion; genital route: sacral or lumbar ganglia
infections recur in response to sunlight, stress, colds, immunosuppression. SUBCLINICAL REACTIVATION COMMON.

Question 7

Varicella Zoster: transmission, herpes type, and primary infection, complications

Answer 7

alpha herpes
respiratory route of transmission
usually occurs in kids. may be asymptomatic or cause chickenpox. mild febrile illnes with blister type rash.
complications: pneumonia (immunosuppressed kids), sepsis, encephalitis, transplacental infection, reye’s syndrome (encephalopathy and hepatitis)

Question 8

Varicella zoster reactivation

Answer 8

latent infection in the sensory ganglia of spinal and/or cranial nerves. reactivated by age, hormones, or immune suppression. recurrence causes herpes zoster (shingles). sever and painful. associated with post herpetic neuralgia.

Question 9

cytomegalovirus: type, epi, transmission

Answer 9

beta herpes virus
spread via saliva, urine, and tears; sexual contact
50-80% of adults positive but numbers vary.

Question 10

CMV infection and reactivation

Answer 10

Primary: infectious mononucleosis; congental/neonatal infection- can cross the placenta. most important viral cause of birth defects in the US. deafness and cognitive deficits common in those kids
Reactivation: latent in myeloid stem cells. reactivated like other herpes viruses. causes pneumonia, retinitis, and encephalitis in immuno-compromised pts.

Question 11

Human herpes 6: type, transmission, primary infection, activation

Answer 11

beta herpes
transmission: saliva. infects >90% of pop by age 3. some variants associated with disease.
primary infection: may cause roseola (rash and fever in little kid; fever breaks suddenly) or generalized febrile illness.
reactivation: latent in monocytes and CNS (maybe). can cause pneumonia and encephalitis in adults. potential and very controversial role in MS and chronic fatigue syndrome. germline integration and transmission possible

Question 12

epstein barr virus: type, epi/transmission; primary infection, other associations

Answer 12

type: gamma herpes
epi/transmission: VERY common (90% of pop). spread via saliva
disease usually latent
primary infection: enters via mucosa. infects B cells. mononucleosis in young adults/older adults. mono is the result of reactive T lymphocytosis due to prolif of latently infected B cells. symptoms due to excess cytokines.
other associations: potential association with B cell lymphomas post-transplant, monoclonal B cell tumors in ppl with HIV. nasopharyngeal carcinoma association.

Question 13

HHV-8: type, epi, disease

Answer 13

gamma herpes: kaposi sarcoma associated herpes virus
epi: Europe and US- rates are low; generally spread via sex. endemic countries: higher seroprevalance (as high as 50%); transmission usually in childhood.
usually virus is latent
kaposi’s sarcoma: highly vascularized tumor of endothelial origin. usually v. rare cancer but common in AIDS pts. also associated w some B cell tumors.

Question 14

Oak/Merck Herpes vaccine

Answer 14

for varicella zoster.
can be used at higher dose in adults over 60 to prevent shingles
establishes latency
live attenuated virus
very very safe. rarely spreads from one person to another.
fully protective immunity in 85%
breakthru infections are milder

Question 15

viral CNS infections: range, access

Answer 15

acute infections range from mild menigitis to severe encephalitis (infection of the brain)
route can be via blood or peripheral nerves. blood transmission to brain rare bc of blood brain barrier. entry via peripheral nerves common in rabies and herpes simplex
consider viral causes of meningitis before bacterial ones

Question 16

5 common causes of viral meningitis; features of viral meningitis

Answer 16

viral most common form of meningitis in ppl over age 10. generally milder than bacterial meningitis. CSF is clear and lymphocytes are present. usually self-resolving.

1. enteroviruses (coxsackie and echovirus; polio)
2. HSV-2 (during primary infection)
3. HIV-1
4. mumps
5. lymphocytic choriomeningitis virus (contact with hamster, guinea pig or mouse urine)

Question 17

viral causes of encephalitis (brain inflammation)

Answer 17

viral encephalitis most common form of encephalitis. causes other neuro symptoms like AMS and seizures.

1. HSV-1. most common cause of severe sporadic acute encephalitis. see with CT. infection localized to temporal lobes. TREAT WITH ACYCLOVIR TO PREVENT 70% MORTALITY.
2. HSV2. neonates common.
3. rabies
4. arboviruses- west nile virus, for example.

Question 18

features of enteroviruses

Answer 18

ssRNA
positive sense
picarnavirus family
non-enveloped
fecal-oral transmission
coxsackievirus, echovirus, poliovirus

Question 19

polio vaccines

Answer 19

salk vaccine: inactivated vaccine given by IM injection. little local mucosal immunity.
oral polio vaccine/sabin vaccine. live attenuated vaccin. cheaper that IPV and elicits strong mucosal immunity in the gut and is shed in the stool. interrupts epidemics. low risk of vaccine-associated polio due to virus reversion.

Question 20

rabies virus: characteristics, pathogenesis, prevention and treatment

Answer 20

negative sense ssRNA
many hosts
in US usually due to bat bites.
long incubation period. virus shed in saliva. negri bodies are diagnostic on autopsy (eosinophilic cytoplasmic inlusions)
death inevitable once virus enters CNS.
post-exposure prophylaxis involving active immunization with the rabies vaccine and passive immunization with antirabies Ig works!
prevent by vaccinating your dog.

Question 21

acute post-infectious encephalitis

Answer 21

often immune-mediated

guillain-barre syndrome after primary HIV, EBV, or CMV infections

Question 22

Reye’s syndrome

Answer 22

kids 4-12
follows acute influenza B or chickenpox infection
encephalitis and liver probs.
linked to aspirin use

Question 23

HTLV-1 associated myelopathy/tropical spastic paraparesis

Answer 23

HTLV-1 (human t lymphotropic virus)
causes immune suppression
neuro features include weakness, muscle stiffness, spasms
rare

Question 24

HAND

Answer 24

HIV associated neurocognitive disorders
HIV infection of CNS
cART has not prevented HAND.
52% of HIV pos ppl have neuropsychiatric impairment. most had mild forms of HAND.
cART may make learning and memory deficits more pronounced.

Question 25

Progressive multifocal leukoencephalopathy

Answer 25

loss of white matter in multiple regions of the brain
clumsiness and progressive weakness
often fatal
caused by reactivation of JS virus (small ssDNA virus)
tysabri increases risk of PML (tysabri is a monoclonal ab used to treat MS)

Question 26

subacute sclerosing panencephalitis

Answer 26

rare complication occurring 1-10 yrs after measles.

Question 27

3 viruses that cause infections that remain localized to the skin

Answer 27

papillomavirus, mulluscum contagiosum virus, orf virus

Question 28

4 (or 5) viruses that cause skin lesions with other systemic infection where the lesions do not contain infectious viruses

Answer 28

herpesviruse 6/7, measles, rubella, parvovirus B19

Question 29

infections that cause skin lesions and systemic infection where the lesions contain infectious viruses

Answer 29

HSV, VZV, coxsacking and echoviruses, and orthopoxviruses (variolla, vaccina, cowpox, monkey pox)