Flashcards in Micro 20 - DNA Virus Part 1 Deck (45):
What does HSV-1 cause?
Oral herpes labialis, "cold sore". Can also cause gingivostomatitis, keratoconjunctivitis, temporal lobe encephalitis, genital herpes.
What nerve does HSV-1 usually lie dormant?
What does HSV-2 cause?
Affects genital regions (multiple painful vesicles). Causes latent infections.
Where does HSV-2 like to lie dormant?
Lies dormant in sacral nerve root ganglia.
What is another name for HHV-3? What does it cause?
It is VZV (Varicella-zoster virus). It depends; on primary infection it causes chickenpox (rarely encephalitis, pneumonia), while reactivation causes herpes zoster (shingles).
Where does VZV likes to lie dormant?
Dorsal ganglia after primary infection.
What are 2 characteristics of shingles?
Stays in a single dermatome and does not cross the midline.
How is VZV spread?
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).
When is the Tzank smear used? What are it's weaknesses?
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.
What do we see in cells infected with HSV-1, HSV-2, or VZV?
Intranuclear eosinophilic inclusions called Type A Cowdry bodies or Type 1 Cowdry inclusions.
What is another name for HHV-4? What does it cause?
Epstein-Barr Virus, it causes mononucleosis.
How is EBV spread? Which type of cells does it like to infect?
Epstein-Barr virus is spread by oral secretion ("kissing disease", affects 15-24 y.o. age group). Infects B cells.
What is the cause of the atypical lymphocytosis that is typical of EBV infection?
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).
What type of virus is the Herpesvirus?
What are the symptoms of infectious mononucleosis?
Fever, sore throat, lymphadenopathy (posterior cervial nodes), exudative pharyngitis.
EBV infection can be confused with strep throat and prescribed with amoxicillin. What happens to the patient?
Maculopapular rash that covers trunk and extremities.
What are the complications of mononucleosis?
Splenomegaly (can rupture), therefore no contact sports or splenic palpation.
How do we diagnose mononucleosis?
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.
What would a likely diagnostic conclusion of someone with mononucleosis symptoms but negative heterophile (Mono) test?
CMV infection, acute HIV, acute toxoplasmosis, viral hepatitis, strep throat.
What are six EBV-associated malignancies?
Hodgkin lymphoma, Burkitt lymphoma, Nasopharyngeal carcinoma, Diffuse large cell lymphoma, Oral hairy leukoplakia, Lymphoproliferative disorders.
What is another name for HHV-5? What cells does it infect?
Cytomegalovirus (CMV). It infects mononuclear cells and polymorphonuclear cells, causing nuclear inclusions called "Owl's Eyes".
What does CMV cause in bone marrow transplant patients?
What does CMV cause in AIDS patients?
Retinitis, ulceration of the GI tract, Esophagitis.
What does HHV-6 cause?
Roseola in children "Sixth disease" or Exanthum subitum.
What does Roseola cause?
Causes High fever (equal or greater than 102F) for 3-5 days, can cause Febrile seizures. After the breaks, the diffuse maculopapular rash begins
What does HHV-7 cause?
Almost all humans are infected by age 5, causes roseola-like symptoms.
What is another name for HHV-8 and what does it cause?
Kaposi Sarcoma-associated Herpesvirus (KSHV), causes highly vascular tumors on that can be seen in skin, but also infects the lungs.
What cells does HHV-8 infect?
Infects spindle cells coming from vascular and lymphatic endothelial tissue (inner lining of blood vessels and lymphatic vessels).
What is the treatment for Kaposi Sarcoma Tumors?
HAART, Topical agents (alitretinoin), Intralesional (vinblastine), call oncologist so he can give Liposomal anthracyclines (daunorubicin, doxorubicin).
What are the different types of Kaposi Sarcoma Tumor? Which one infects the HIV patients?
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.
What is the mechanism of acyclovir?
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.
Which diseases do we use acyclovir?
HSV-1, HSV-2, VZV, EBV.
Which drug is preferred for herpes zoster?
Famciclovir is preferred over acyclovir for herpes zoster.
How come acyclovir, famciclovir and valacyclovir are useless against CMV?
Because the virus lacks viral thymidine kinase.
What drug do we use against CMV?
Ganciclovir, which is activated by CMV viral kinase and inhibits viral DNA polymerase.
What are the adverse effects of Ganciclovir?
Bone marrow suppression, renal toxicity.
What is the mechanism of Foscarnet? When do we use it?
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).
What can use for the treatment of HSV1, HSV2, VZV?
Acyclovir, Valacyclovir, Famciclovir.
What can we use for the treatment of CMV?
What group of patients is prone to esophagitis caused by CMV?
AIDS patients with less than 50 CD4.
What are Downey cells?
T-cells that are responding to an EBV infection.
RFF: Dark purple nodules on the skin in an HIV patient.
RFF: Temporal lobe encephalitis.
RFF: Owl's eye inclusion in organ tissue.