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MM > Lecture 27 > Flashcards

Lecture 27 Flashcards

1
Q

Herpes Virus

A

HHV-1
Herpes Simplex virus - 1
- alpha sub-family
- oral and or genital herpes

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2
Q

Herpes general characteristics

A

large genome
linear dsDNA
complex viruses - may code for more than 30 viral proteins
genetically diverse
enveloped
replication and assembly in the host cell nucleus

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3
Q

HSV structure

A

envelope glycoproteins attachment of host virus to host cells
tegument proteins and enzymes for replication
capside surrounds the core
DNA core genome

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4
Q

HSV-1

A

over 90% of people from under developed area have HSV-1 by two y.o.
fever blisters
herpes encephalitis
- 70% mortality rate

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5
Q

HSV-1 infections

A

herpes keratitis
- permanent scarring, cornea damage, blindness

Herpes labialis
-gingivostomatitis always caused by HSV-1 in toddlers and children

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6
Q

HSV-1 latency

A

stays in trigeminal ganglion for life

gene expression is repressed except LAT

Molecular mechanisms unknown

CD8 cells and interferon gamma important for latency

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7
Q

HSV -1 reactivation

A

exact reasons unknown

  • UV radiation
  • fever
  • stress
  • immune suppression

viruses return to initial site of infection, fluid contains infectious virons

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8
Q

HSV - 1 immune responses

A
  1. cell mediated immunity in an inflammatory response
  2. antibodies limit spreading
  3. ICP 47 blocks MHC class 1 antigen
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9
Q

HSV transmission

A

HSV-1

  • oral contact
  • skin lesion contact
  • 10% genital infection

HSV-2

  • sexual contact 22% US adults
  • mother to infant devastating
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10
Q

HSV prevention and control

A

no vaccine

avoid direct contact

condoms

pregnant women with genital Herpes should get a C-section

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11
Q

Varicella-Zoster virus

A
  • human herpes virus 3
  • causes chicken pox
  • causes Zoster or Shingles
  • Alpha Herpes virus
  • predominantly respiratory route
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12
Q

Varicella-Zoster virus

A
  • over 90% of adults have in developed countries
  • Herpes Zoster caused by reactivation from latent viruses
  • incidence rises with age
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13
Q

Varicella

A

chicken pox

one of 5 classic childhood exanthems
- rubella, roseola, fifth disease and measles

primary infection more severe in adults

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14
Q

Herpes zoster

A

zoster belt is a recurrent infection from latent virus

severe pain innervated by the nerve

post-herpetic neuralgia chronic pain more in seniors

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15
Q

Varicella treatment

A

not necessary for healthy children
infection encouraged for life immunity

ACV, FAMCICLOVIR and VALACICLOVIR
- adults in immunocompromised

Required larger dose than HSV
- VZV DNA polymerase less sensitive

pain killers

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16
Q

VZV vaccine

A

Takahashi et al. developed a live attenuated VZV vaccine

US licensed Varivax by Merck

17
Q

Epstein-Barr virus

A

gamma herpes virus

ultimate B lymphocyte parasite
- African Burkett lymphoma

Infectious mononucleosis
Hodgkins disease
nasapharyngeal carcinoma

18
Q

EBV

A

limited host range

primary cell receptor is CR2 or CD21

B cells human and monkey

epithelial cells pharynx and nasopharynx

19
Q

EBV disease

A

transmitted in saliva

90% infected adults may shed virus for years

EBV as participating factor

  1. AFBL - malaria pt’s
  2. NPC - southeastern chinese
  3. hodgkins disease - 30-50%
20
Q

EBV treatment

A

no treatment

no vaccine

lifelong immunity

early exposure best way to prevent benign in children

21
Q

Cytomegalovirus

A
  • beta herpes virinae
  • lymphotrophic
  • largest genome
  • carries mRNA in viron
  • human CMV replicates in human cells only
  • latency
22
Q

CMV patho

A

similar to other herpes viruses

prefer latency

reactivated by immunosuppression such as HIV

23
Q

CMV transmission

A
  • found in urine, blood, saliva, tears, breast milk, semen, stool
  • congenital viral disease 2.5 infected before birth
24
Q

CMV

A

primary infection blood, recurrent infection from cervix can be sexually transmitted

25
Q

CMV treatment

A

ganciclovir (GCV- similar to ACV but more toxic)
Valganciclovir - better bio-availability
Cidofovir - viral enzyme not required for activation
Foscarnet - inhibits DNA polymerase

26
Q

CMV prevention and control

A

condom or abstinence

transplantation and transfusion- screening

no vaccine

27
Q

HHB6 and 7

A 
roseololvirus 
- isolated from an AIDS pt originally 
- exanthem subitum or roseola
HHV6 is lymphotrophic
100% of adults are positive
infection occurs early in life
replicates in salivary gland
latency in T cell and monocytes
Mechanism very similar to CMV
28
Q

picornaviruses

A

big family

  • 230 members
  • enterovirus, rhinovirus, hepatovirus

no membrane, positive RNA genome
- 7200-8450 base

encodes polyprotein precursor

29
Q

picornavirus

A

use VP1 for surface receptor recognition

ICAM-1 - rhinovirus

CD55

PVR/CD155- polio virus

30
Q

picorna viruses

A

inhibits synthesis of cellular RNA and proteins

leads cytopathological effects

viral genome packaged into capside
- 100,000 virons per cell released in 3-4 hours

31
Q

enteroviruses

A

do not usually cause enteric disease

follow fecal oral route

entry by oralpharynx, intestinal and respiratory tracts

polio virus infects skeletal muscles and travels to brain via innervating nerves

32
Q

polio syndrome

A

asymptomatic for 90% of infection

abortive polio myelitis- minor illness 5%

non-paralytic polio myelitis - 1-2%
Aseptic meningitis CNS

paralytic polio - .1-2%, most severe
- polio virus type 1 85%

33
Q

post-polio syndrome

A

polio myelitis sequelae

  • 30-40 years later
  • 20-80% of original victims

deterioration of originally effected muscles

  • no virus detected
  • due to loss of neurons
34
Q

rhino virus

A

most important cause of common cold and URI 50%

  • over 100 serotypes
  • aerosols and fomites
  • non-enveloped virus
  • receptor ICAM-1

common cold is not influenza
- other viruses responsible for the common cold such as: enterovirus, coronavirus, adenovirus, parainfluenza virus, etc

35
Q

rhino virus patho

A

preferentially grown at 33C not 37C, hence infects upper respiratory tract such as nasal mucosa

infected cells release bradykinin and histamine (runny nose and congestion)

interferon in response to infection controls the progression but cause the symptoms

36
Q

pleconaril

A

interacts with hydrophobic pocket of VP1

in enteroviruses, this prevents the virus from exposing it’s RNA

in rhino viruses it also prevents the virus from attaching itself to host cell

37
Q

pleconaril prevention and treatment

A

hand wash and disinfection

pleconaril

ICAM-1 analog

no vaccine

MM (6 decks)

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