Micro - Virology (Part 2) Flashcards Preview

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Flashcards in Micro - Virology (Part 2) Deck (64)
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1
Q

A boy has spots on his oral mucosa that are red with a blue-white center and a maculopapular rash on his chest, as shown. What is the cause?

A

Rubeola (measles) virus; note the Koplik spots on the inner cheek and the diffuse rash

2
Q

A patient presents with ulcerating painful lesions on her genitals similar to the image shown here. What is the diagnosis?

A

Herpes genitalis

3
Q

How long is the incubation period of the hepatitis B virus?

A

3 months

4
Q

What characteristics do hepatitis B and C have in common?

A

They are both transmitted by blood, they both have chronic carriers, and they both can cause chronic active hepatitis, cirrhosis, and hepatocellular carcinoma

5
Q

Which patient populations are at high risk for hepatitis C?

A

Intravenous drug users and posttransfusion patients

6
Q

Infection with which hepatitis virus requires coinfection with hepatitis B virus?

A

Hepatitis D virus (remember: Hepatitis D is Defective and Dependent on hepatitis B virus coinfection)

7
Q

What are two severe long-term sequelae of chronic infection with hepatitis C?

A

Cirrhosis and carcinoma (remember: Hep C: Chronic, Cirrhosis, Carcinoma Carrier)

8
Q

A bat researcher develops fever, malaise, photophobia, and coma. He dies. Pathology shows cytoplasmic inclusions in his neurons. Etiology?

A

Rabies virus; note the Negri bodies on histopathology, which are characteristic of rabies

9
Q

Which has a worse prognosis: coinfection with hepatitis B and hepatitis D, or superinfection of hepatitis D in a patient with hepatitis B?

A

Superinfection leads to more severe illness

10
Q

Which two types of hepatitis are trasmitted through the bowels?

A

Hep A (primarily fecal-oral) and hep E (enteric) (remember: "the vowels hit your bowels")

11
Q

Why are hepatitis A and E viruses infectious via the fecal-oral route, whereas hepatitis B, C, and D are not?

A

Because enveloped viruses (B, C, D) are destroyed by the gut whereas naked viruses (A, E) are not

12
Q

What are the signs and symptoms of hepatitis infection?

A

Episodic fevers, jaundice, and elevated aspartate aminotransferase and alanine aminotransferase levels

13
Q

Which serologic marker indicates prior infection with and is protective against reinfection with hepatitis A infection?

A

Immunoglobulin G hepatitis A virus antibody

14
Q

Which serologic marker detects active hepatitis A infection?

A

Immunoglobulin M hepatitis A virus antibody

15
Q

What does the continued presence of hepatitis B surface antigen in serum mean?

A

A chronic infection and carrier status for the patient

16
Q

Which antibody is protective against hepatitis B infection?

A

Hepatitis B surface antibody

17
Q

Which hepatitis serologic marker is positive during the "window period"?

A

Hepatitis B core antibody

18
Q

What is the significance of immunoglobulin M hepatitis B core antibody vs immunoglobulin G hepatitis B core antibody on serologic studies?

A

Regarding hepatitis B virus core antibodies, immunoglobulin M is a marker for recent disease whereas immunoglobulin G is a marker for chronic disease

19
Q

What is the significance of hepatitis B envelope antigen?

A

The level of the envelope antigen in serum is a marker of the infectivity of the patient because it indicates active viral replication

20
Q

What does the presence of hepatitis B e antibody indicate?

A

Presence of antibodies to the envelope antigen indicates lower transmissibility

21
Q

The presence of which hepatitis B serologic marker would be seen in an asymptomatic patient in the hepatitis B incubation period?

A

Hepatitis B surface antigen

22
Q

What pattern of transaminase elevation is seen in viral hepatitis? In alcoholic hepatitis?

A

In viral hepatitis, alanine aminotransferase > aspartate aminotransferase; in alcoholic hepatitis, aspartate aminotransferase > alanine aminotransferase

23
Q

In acute hepatitis B virus infection, hepatitis B surface antigen tests would be (+/-) _____, hepatitis B surface antibody would be (+/-) _____, and hepatitis B core antibody would be (+/-) _____.

A

Positive; negative; positive (immunoglobulin M hepatitis B core antibody in acute stage, immunoglobulin G hepatitis B core antibody in chronic or recovered phase)

24
Q

In the window phase of hepatitis B virus infection, hepatitis B surface antigen tests would be (+/-) _____, hepatitis B surface antibody would be (+/-) _____, and hepatitis B core antibody would be (+/-) _____.

A

Hepatitis B surface antigen negative; hepatitis B surface antibody negative; hepatitis B core antibody positive

25
Q

After complete recovery from hepatitis B virus infection, hepatitis B surface antigen tests would be (+/-) _____, hepatitis B surface antibody would be (+/-) _____, and hepatitis B core antibody would be (+/-) _____.

A

Hepatitis B surface antigen negative; hepatitis B surface antibody positive; hepatitis B core antibody positive

26
Q

Iin a chronic carrier of hepatitis B virus infection, hepatitis B surface antigen tests would be (+/-) _____, hepatitis B surface antibody would be (+/-) _____ and hepatitis B core antibody would be (+/-) _____.

A

Hepatitis B surface antigen positive; hepatitis B surface antibody negative; hepatitis B core antigen positive

27
Q

In an individual immunized against hepatitis B virus infection, hepatitis B surface antigen tests would be (+/-) _____, hepatitis B surface antibody would be (+/-) _____ and hepatitis B core antigen would be (+/-) _____.

A

Hepatitis B surface antigen negative; hepatitis B surface antibody positive; hepatitis B core antibody negative

28
Q

Why does hepatitis B surface antibody appear negative during the window period after hepatitis B virus infection?

A

Because all available hepatitis B surface antibody is bound to hepatitis B surface antigen, making it undetectable on assay

29
Q

The p24gag protein is located in the _____ (envelope/matrix/capsid) of HIV.

A

Capsid

30
Q

Glycoproteins 41 and 120 are located in the _____ (envelope/matrix/capsid) of HIV.

A

Envelope

31
Q

What process must occur in order for HIV genetic material to be integrated into the host genome?

A

Reverse transcriptase converts RNA into double-stranded DNA and it is then integrated into the host genome

32
Q

What molecules does HIV bind to on T cells?

A

CXCR4 and CD4

33
Q

What molecules does HIV bind to on macrophages?

A

CCR5 and CD4

34
Q

People homozygous for mutations of which receptor are immune to HIV infection?

A

CCR5; HIV cannot invade cells without the presence of CCR5; heterozygosity leads to a slower course of illness

35
Q

The p17 protein is located in the _____ (envelope/matrix/capsid) of HIV.

A

Matrix

36
Q

Which lab technique is used to screen for HIV infection?

A

Enzyme-linked immunosorbent assay

37
Q

Why is HIV diagnosis with enzyme-linked immunosorbent assay not considered conclusive evidence of HIV infection?

A

Enzyme-linked immunosorbent assay for HIV has a high false-positive rate and low threshold; ie, enzyme-linked immunosorbent assay is sensitive and can rule out disease

38
Q

In diagnosing HIV, if an enzyme-linked immunosorbent assay is positive, which test is used to confirm the diagnosis?

A

Western blot is highly specific with a high false-negative rate and a high threshold; it is used to rule in disease after a positive enzyme-linked immunosorbent assay test

39
Q

Which lab technique is used to monitor response to therapy in patients who are HIV positive?

A

HIV polymerase chain reaction (viral load) tests allow for quantification of viral activity in the body

40
Q

Both the enzyme-linked immunosorbent assay and the Western blot assay for HIV detect the presence of what molecules in serum?

A

Antibodies

41
Q

Both the enzyme-linked immunosorbent assay and the Western blot assay are falsely negative in which group of patients?

A

Those who are newly infected (within first 2 months)

42
Q

Both the enzyme-linked immunosorbent assay and the Western blot assay are falsely positive in which group of patients?

A

Babies born to infected mothers, because antibodies to anti-glycoprotein 120 can cross the placenta

43
Q

The diagnosis of AIDS is made using what criteria?

A

Confirmed HIV infection; plus CD4+ cell count < 200/mm³, a CD4 to CD8 ratio < 1.5, or presence of an AIDS-defining illness such as Pneumocystis Jiroveci pneumonia

44
Q

During what two time periods does the CD4+ cell count decrease after HIV infection?

A

There is a decrease in CD4+ cell count during the acute phase followed by recovery and then a slow decline as the illness progresses

45
Q

What is the clinical presentation of acute HIV infection?

A

Flu-like illness

46
Q

Opportunistic infections and malignancies usually occur how long after an individual is infected with HIV?

A

Between 3 and 10 or more years (the immunodeficiency phase)

47
Q

What are the four stages of HIV infection?

A

The Four Fs: Flulike (acute), Feeling fine (latent), Falling count, and Final crisis

48
Q

Which AIDS-related opportunistic infections affect the brain?

A

Cryptococcal meningitis, toxoplasmosis, cytomegalovirus encephalopathy, AIDS dementia, progressive multifocal leukoencephalopathy (JC virus)

49
Q

Which AIDS-related opportunistic infection affects the eyes?

A

Cytomegalovirus retinitis

50
Q

Which AIDS-related opportunistic infections affect the mouth and throat?

A

Thrush (Candida), herpes simplex virus, cytomegalovirus, and Epstein-Barr virus (oral hairy leukoplakia)

51
Q

Which AIDS-related opportunistic infections affect the lungs?

A

Pneumocystis jiroveci pneumonia, tuberculosis, and histoplasmosis

52
Q

Which AIDS-related opportunistic infections affect the gastrointestinal tract?

A

Cryptosporidiosis, Mycobacterium avium-intracellulare complex, cytomegalovirus colitis, Epstein-Barr virus (as gastrointestinal lymphoma), and Isospora belli

53
Q

Which AIDS-related opportunistic infections affect the skin?

A

Varicella zoster virus (shingles) and human herpes virus type 8 (Kaposi sarcoma)

54
Q

Which AIDS-related opportunistic infections affect the genitals?

A

Genital herpes and human papillomavirus (genital warts, and cervical cancer)

55
Q

An HIV-positive patient with a CD4+ cell count < 400/mm³ is at increased risk for which infections?

A

Oral thrush, tinea pedis, reactivation of zoster, reactivation of tuberculosis, and other bacterial infections

56
Q

An HIV-positive patient with a CD4+ cell count <100/mm³ is at increased risk for which infections?

A

Candidal esophagitis, toxoplasmosis, and histoplasmosis

57
Q

An HIV-positive patient with a CD4+ count < 50/mm³ is at increased risk for which infections?

A

Cytomegalovirus retinitis and esophagitis, disseminated Mycobacterium avium intracellulare infection, and cryptococcal meningoencephalitis

58
Q

An HIV-positive patient with a CD4+ cell count < 200/mm³ is at increased risk for which infections?

A

Pneumocystic pneumonia, reactivation of herpes simplex virus infection, cryptosporidiosis, Isospora infection, and disseminated coccidioidomycosis

59
Q

Kaposi sarcoma is caused by _____, while invasive cervical carcinoma is caused by _____.

A

Human herpesvirus type 8; human papillomavirus

60
Q

What four malignancies are associated with HIV?

A

Kaposi sarcoma, invasive cervical carcinoma, primary central nervous system lymphoma and non-hodgkins lymphoma

61
Q

What are the histopathologic findings of HIV encephalitis?

A

Microglial nodules with multinucleated giant cells

62
Q

In HIV encephalitis, how does the virus gain access to the central nervous system?

A

Via infected macrophages

63
Q

A 75-year-old woman with fever and burning pain over her shoulder later develops the rash shown here. What is the diagnosis?

A

Herpes zoster, caused by VZV that remains latent in the dorsal root or trigeminal ganglia and re-emerges in a dermatomal distribution

64
Q

A patent presents with pustules on the lips similar to the image shown here. What virus causes this?

A

This is herpes labialis, caused by herpes simplex virus type 1