Viral Skin Infections Flashcards Preview

MSK Week 1 > Viral Skin Infections > Flashcards

Flashcards in Viral Skin Infections Deck (61):
1

What type of nucleic acids do we have in Herpes viruses

Double stranded DNA

2

How can we distinguish the herpes viruses under microscopy?

You can't

3

What are herpes viruses susceptible to generally?

Susceptible to drying, inactivation by heat, mild detergent and solvents because of their membrane envelope

4

Where do herpesviruses replicate?

Nucleus

5

Types of Herpes Viruses?

Alpha Beta Gamma

6

What viral types fall into the Alpha category?

HSV-1 HSV-2 VZV

7

Presentation of HSV-1

Labial lesions (cold sores), fever blister, keratitis, encephalitis

8

Presentation of HSV-2

Genital lesions, severe CNS disease in neonates (congenital herpes infection)

9

Presentation of VZV

Herpes Zoster - Chicken pox, shingles - Transmitted by respiratory droplets

10

Where do alpha herpes viruses stay latent?

Sensory ganglia/neurons

11

What viral types fall into the Beta category?

CMV HHV-6 HHV-7

12

Which category, Alpha or Beta, has the longest replicative phase?

Beta Alpha's is short

13

Where do Beta viruses stay latent?

Monocytes/macrophages Lymphocytes Endothelial cells

14

Monospot test result for CMV?

Negative

15

Histological finding for CMV?

"Owl-eye" inclusions

16

HHV-6 is associated with what symptoms? How is it transmitted?

Roseola Transmitted by saliva

17

Roseola?

High fevers for several days that can cause seizures followed by diffuse macular rash.

18

What viral types fall into the Gamma category?

EBV (HHV-4), KSHV (HHV-8)

Karposi's sarcomma-associated herpesvirus: these viruses cause Karposi's sarcoma, a cancer common in AIDs patients 

Epstein-Barr virus: cause of infectious mononucleosis (glandular fever). Infants are susceptible to EBV after their maternal antibody protection dissapears 

19

What cells are infected by Gamma category viruses?

Epithelial cells and lymphocytes

20

What cells do gamma category viruses stay latent in?

Lympocytes and endothelial cells

21

Mononucleosis

Flu-like symptoms caused by HHV-4 (EBV) 

 

Fever, hepatosplenomegaly, pharyngitis

22

Besides EBV, what virus type causes mononucleosis?

CMV (HHV-5) 

23

What cells does EBV target specifically?

B cells

24

EBV monospot test result?

Positive

25

HHV-8 is associated with what?

A Kaposi sarcoma, a neoplasm of endothelial cells. Seen in HIV/AIDS patients and transplant patients. Dark, violaceous, flat but nodular skin lesions

26

How is HHV-8 transmitted?

Sexually

27

Life Cycle of Herpes

1. Lytic Replication 2. Latency 3. Reactivation

28

Lytic Phase, generally:

In epithelial cells, viruses take over cellular machineries for replication, synthesis of macromolecules and virus assembly, and eventually leads to cell death

29

Proteins made by viruses do what, generally:

Proteins are produced that prevent premature programmed cell death or apoptosis and evade immune responses

30

What DNA replication enzymes can herpes viruses make?

All herpesviruses encode enzymes used in DNA replication: 1. ribonucleotide reductase 2. thymidine kinase 3. primase/helicase 4. DNA polymerase

31

What are the immediate early genes?

Transcriptional regulatory factors that turn on delayed early gene expression

32

What are the delayed early genes?

DNA replication enzymes

33

What occurs during the DNA replication phase?

DNA replicates as covalently closed circle, followed by the rolling circle mechanism

34

What are the late genes?

Structural proteins

35

General description of the Assembly/egress phase for viruses

Capsid generated around created proteins, primary envelopment (nuclear membrane envelops it), leave nuclear membrane, enveloped by golgi (secondary envelopment), exits

36

What is occurring during the latency phase?

Circular viral genome (episome) maintained in neurons without replication; expresses LAT transcript, which plays a role in latency establishment and evades immune detection

37

Reactivation of HSV-2 - Triggers

Stress, sunlight, trauma, menstruation

38

Triggers for VZV reactivation

Immune suppression, depressed cell-mediated immunity (age)

39

Reactivation process for HSV-2

Involved limited viral replication in neurons, transport of viral capsid to axonal terminals and egress to regions innervated by specific neurons. Asymptomatic reactivation facilitates virus spread to naive hosts.

40

Clinical features of HSV primary infection?

Accompanied by systemic symptoms such as fever and malaise

41

Clinical features of HSV reactivation

Accompanied by prodromal symptoms like pain, numbness, itchiness, tingling sensation

42

Clinical features of HSV acute infection

Direct destruction of tissues or induction of immunopathologic response 1. Characteristic skin lesions are vesicles with an erythematous base 2. Usually grouped at a single anatomic site

43

HSV Type, Age, and outcome for: Ocular Herpes

1 All ages Resolution with occasional visual impairment

44

HSV Type, Age, and outcome for: Oral herpes

Usually 1 All ages Just resolves

45

HSV Type, Age, and outcome for: Genital herpes

Usually 2 Adolescents and adults Just resolves

46

HSV Type, Age, and outcome for: Neonatal herpes

Usually 2 Age: 0-4 weeks Leads to development impairment

47

HSV Type, Age, and outcome for: Meningoencephalitis

2 Adolescents, adults Just resolves

48

HSV Type, Age, and outcome for: Encephalitis

1 All ages Leads to severe neurological impairment and death

49

HSV Type, Age, and outcome for: Disseminated herpes

Usually 1 All ages Can resolve or kill you

50

How to diagnose Herpes infections

1. viral culture 2. Tzanck smear (Smear of an opened skin vesicle to detect mononucleated giant cells) 3. serology 4. PCR

51

How does Herpes Thymidine Kinase Anti-Herpes Therapy work?

DNA chain terminator, specifically activated by the viral TK. Incorporates into the viral DNA and terminates the DNA replication of viruses

52

Acyclovir

A TK antiherpes that inhibits viral DNA polymerase and chain terminates

53

Ganciclovir

CMV does not have a viral TK but can be inhibited by ganciclovir. A viral protein kinase homologue is involved in activating ganciclovir

54

Treatment for CMV?

Ganciclovir

55

Foscarnet?

Used in the treatment of CMV retinitis in AIDS patients receiving AZT therapy. Has renal side effects and must be administered by IV continuously

56

How does Foscarnet work?

Binds directly to the pyrophosphate-binding sites of RNA or DNA polymerases. Does not need to be activated by cellular or viral kinases

57

Varivax?

Live-Attenuated VZV vaccine

58

Who is Varivax recommended for?

- Kids - Non pregnant women of child bearing age - Those with humoral immunodeficiencies - HIV+ children with age specific CD4+counts greater than or equal to 25%

59

Varivax not recommended for?

- Pregnant women - HIV+ persons or persons with other cellular immunodeficiencies - People receiving immunosuppressive therapy, steroids, etc.

60

Which is more severe? Primary infection or Recurrent?

Primary - No immunity yet

61

Q image thumb

A image thumb