Micro 20 - DNA Virus Part 1

Question 1

What does HSV-1 cause?

Answer 1

Oral herpes labialis, “cold sore”. Can also cause gingivostomatitis, keratoconjunctivitis, temporal lobe encephalitis, genital herpes.

Question 2

What nerve does HSV-1 usually lie dormant?

Answer 2

Trigeminal ganglia.

Question 3

What does HSV-2 cause?

Answer 3

Affects genital regions (multiple painful vesicles). Causes latent infections.

Question 4

Where does HSV-2 like to lie dormant?

Answer 4

Lies dormant in sacral nerve root ganglia.

Question 5

What is another name for HHV-3? What does it cause?

Answer 5

It is VZV (Varicella-zoster virus). It depends; on primary infection it causes chickenpox (rarely encephalitis, pneumonia), while reactivation causes herpes zoster (shingles).

Question 6

Where does VZV likes to lie dormant?

Answer 6

Dorsal ganglia after primary infection.

Question 7

What are 2 characteristics of shingles?

Answer 7

Stays in a single dermatome and does not cross the midline.

Question 8

How is VZV spread?

Answer 8

Respiratory route. On shingles it is by direct contact with active lesion unless the patient is immunocompromised and is shedding the virus everywhere (can spread by ventilation system).

Question 9

When is the Tzank smear used? What are it’s weaknesses?

Answer 9

Used to detect HSV-1, HSV-2, or VZV but it cannot differentiate between them. It is positive when multinucleated giant cells are seen. Also has low specificity and low sensitivity. Better use a PCR test of the vesicular fluid for diagnosis.

Question 10

What do we see in cells infected with HSV-1, HSV-2, or VZV?

Answer 10

Intranuclear eosinophilic inclusions called Type A Cowdry bodies or Type 1 Cowdry inclusions.

Question 11

What is another name for HHV-4? What does it cause?

Answer 11

Epstein-Barr Virus, it causes mononucleosis.

Question 12

How is EBV spread? Which type of cells does it like to infect?

Answer 12

Epstein-Barr virus is spread by oral secretion (“kissing disease”, affects 15-24 y.o. age group). Infects B cells.

Question 13

What is the cause of the atypical lymphocytosis that is typical of EBV infection?

Answer 13

Because EBV likes to infect B cells. When system detects compromised B cells, it mounts a surge of cytotoxic T cells, producing atypical lymphocytosis. Produces Downey cells (atypical T cells that have a foamy-appearing basophilic cytoplasm).

Question 14

What type of virus is the Herpesvirus?

Answer 14

DNA Virus.

Question 15

What are the symptoms of infectious mononucleosis?

Answer 15

Fever, sore throat, lymphadenopathy (posterior cervial nodes), exudative pharyngitis.

Question 16

EBV infection can be confused with strep throat and prescribed with amoxicillin. What happens to the patient?

Answer 16

Maculopapular rash that covers trunk and extremities.

Question 17

What are the complications of mononucleosis?

Answer 17

Splenomegaly (can rupture), therefore no contact sports or splenic palpation.

Question 18

How do we diagnose mononucleosis?

Answer 18

Monospot test: detects heterophile antibodies, antigens found in horse, sheep and beef RBCs (they are made in the body by unknown reason). Has high sensitivity and specificity. Can also test antbodies (IgM and IgG) specific for EBV.

Question 19

What would a likely diagnostic conclusion of someone with mononucleosis symptoms but negative heterophile (Mono) test?

Answer 19

CMV infection, acute HIV, acute toxoplasmosis, viral hepatitis, strep throat.

Question 20

What are six EBV-associated malignancies?

Answer 20

Hodgkin lymphoma, Burkitt lymphoma, Nasopharyngeal carcinoma, Diffuse large cell lymphoma, Oral hairy leukoplakia, Lymphoproliferative disorders.

Question 21

What is another name for HHV-5? What cells does it infect?

Answer 21

Cytomegalovirus (CMV). It infects mononuclear cells and polymorphonuclear cells, causing nuclear inclusions called “Owl’s Eyes”.

Question 22

What does CMV cause in bone marrow transplant patients?

Answer 22

Life-threatening pneumonia.

Question 23

What does CMV cause in AIDS patients?

Answer 23

Retinitis, ulceration of the GI tract, Esophagitis.

Question 24

What does HHV-6 cause?

Answer 24

Roseola in children “Sixth disease” or Exanthum subitum.

Question 25

What does Roseola cause?

Answer 25

Causes High fever (equal or greater than 102F) for 3-5 days, can cause Febrile seizures. After the breaks, the diffuse maculopapular rash begins

Question 26

What does HHV-7 cause?

Answer 26

Almost all humans are infected by age 5, causes roseola-like symptoms.

Question 27

What is another name for HHV-8 and what does it cause?

Answer 27

Kaposi Sarcoma-associated Herpesvirus (KSHV), causes highly vascular tumors on that can be seen in skin, but also infects the lungs.

Question 28

What cells does HHV-8 infect?

Answer 28

Infects spindle cells coming from vascular and lymphatic endothelial tissue (inner lining of blood vessels and lymphatic vessels).

Question 29

What is the treatment for Kaposi Sarcoma Tumors?

Answer 29

HAART, Topical agents (alitretinoin), Intralesional (vinblastine), call oncologist so he can give Liposomal anthracyclines (daunorubicin, doxorubicin).

Question 30

What are the different types of Kaposi Sarcoma Tumor? Which one infects the HIV patients?

Answer 30

Classic type is slow growing tumor w/o much potential for metastasis. Epidemic type is the one found in HIV/AIDS patients. Immunocompromised type found in transplant patients.

Question 31

What is the mechanism of acyclovir?

Answer 31

It is a guanosine analog. It is first phosphorylated by viral thymidine kinase, making it very specific to infected cells, then phosphorylated to its active triphosphate form by host cell, which is then incorporated into the viral DNA, inhibiting DNA polymerase and terminates that viral DNA chain.

Question 32

Which diseases do we use acyclovir?

Answer 32

HSV-1, HSV-2, VZV, EBV.

Question 33

Which drug is preferred for herpes zoster?

Answer 33

Famciclovir is preferred over acyclovir for herpes zoster.

Question 34

How come acyclovir, famciclovir and valacyclovir are useless against CMV?

Answer 34

Because the virus lacks viral thymidine kinase.

Question 35

What drug do we use against CMV?

Answer 35

Ganciclovir, which is activated by CMV viral kinase and inhibits viral DNA polymerase.

Question 36

What are the adverse effects of Ganciclovir?

Answer 36

Bone marrow suppression, renal toxicity.

Question 37

What is the mechanism of Foscarnet? When do we use it?

Answer 37

Inhibits DNA polymerase and does not require activation by viral kinase. We use it in cases of HHS resistance (HSV resistant to acyclovir or CMV retinitis resistant to ganciclovir).

Question 38

What can use for the treatment of HSV1, HSV2, VZV?

Answer 38

Acyclovir, Valacyclovir, Famciclovir.

Question 39

What can we use for the treatment of CMV?

Answer 39

Ganciclovir, Foscarnet.

Question 40

What group of patients is prone to esophagitis caused by CMV?

Answer 40

AIDS patients with less than 50 CD4.

Question 41

What are Downey cells?

Answer 41

T-cells that are responding to an EBV infection.

Question 42

RFF: Dark purple nodules on the skin in an HIV patient.

Answer 42

Kaposi sarcoma.

Question 43

RFF: Temporal lobe encephalitis.

Answer 43

HSV-1.

Question 44

RFF: Owl’s eye inclusion in organ tissue.

Answer 44

CMV.

Question 45

RFF: Intranuclear eosinophilic droplets.

Answer 45

Type A Cowdry bodies seen in HSV, CMV infections.