Micro - Virology Part 2 Flashcards
A boy has spots on his oral mucosa that are red with a blue-white center and a maculopapular rash on his chest. What is the cause?
Rubeola (measles) virus; note the Koplik spots on the inner cheek and the diffuse rash
A patient presents with ulcerating painful lesions on her genitals. What is the diagnosis?
Herpes genitalis
How long is the incubation period of the hepatitis B virus?
3 months
What characteristics do hepatitis B and C have in common?
They are both transmitted by blood, they both have chronic carriers, and they both can cause chronic active hepatitis, cirrhosis, and hepatocellular carcinoma
Which patient populations are at high risk for hepatitis C?
Intravenous drug users and posttransfusion patients
Infection with which hepatitis virus requires coinfection with hepatitis B virus?
Hepatitis D virus (remember: Hepatitis D is Defective and Dependent on hepatitis B virus coinfection)
What are two severe long-term sequelae of chronic infection with hepatitis C?
Cirrhosis and carcinoma (remember: Hep C: Chronic, Cirrhosis, Carcinoma Carrier)
A bat researcher develops fever, malaise, photophobia, and coma. He dies. Pathology shows cytoplasmic inclusions in his neurons. Etiology?
Rabies virus; note the Negri bodies on histopathology, which are characteristic of rabies
Which has a worse prognosis: coinfection with hepatitis B and hepatitis D, or superinfection of hepatitis D in a patient with hepatitis B?
Superinfection leads to more severe illness
Which two types of hepatitis are trasmitted through the bowels?
Hep A (primarily fecal-oral) and hep E (enteric) (remember: “the vowels hit your bowels”)
Why are hepatitis A and E viruses infectious via the fecal-oral route, whereas hepatitis B, C, and D are not?
Because enveloped viruses (B, C, D) are destroyed by the gut whereas naked viruses (A, E) are not
What are the signs and symptoms of hepatitis infection?
Episodic fevers, jaundice, and elevated aspartate aminotransferase and alanine aminotransferase levels
Which serologic marker indicates prior infection with and is protective against reinfection with hepatitis A infection?
Immunoglobulin G hepatitis A virus antibody
Which serologic marker detects active hepatitis A infection?
Immunoglobulin M hepatitis A virus antibody
What does the continued presence of hepatitis B surface antigen in serum mean?
A chronic infection and carrier status for the patient
Which antibody is protective against hepatitis B infection?
Hepatitis B surface antibody
Which hepatitis serologic marker is positive during the “window period”?
Hepatitis B core antibody
What is the significance of immunoglobulin M hepatitis B core antibody vs immunoglobulin G hepatitis B core antibody on serologic studies?
Regarding hepatitis B virus core antibodies, immunoglobulin M is a marker for recent disease whereas immunoglobulin G is a marker for chronic disease
What is the significance of hepatitis B envelope antigen?
The level of the envelope antigen in serum is a marker of the infectivity of the patient because it indicates active viral replication
What does the presence of hepatitis B e antibody indicate?
Presence of antibodies to the envelope antigen indicates lower transmissibility
The presence of which hepatitis B serologic marker would be seen in an asymptomatic patient in the hepatitis B incubation period?
Hepatitis B surface antigen
What pattern of transaminase elevation is seen in viral hepatitis? In alcoholic hepatitis?
In viral hepatitis, alanine aminotransferase > aspartate aminotransferase; in alcoholic hepatitis, aspartate aminotransferase > alanine aminotransferase
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 (+/-) _____.
Positive; negative; positive (immunoglobulin M hepatitis B core antibody in acute stage, immunoglobulin G hepatitis B core antibody in chronic or recovered phase)
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 (+/-) _____.
Hepatitis B surface antigen negative; hepatitis B surface antibody negative; hepatitis B core antibody positive
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 (+/-) _____.
Hepatitis B surface antigen negative; hepatitis B surface antibody positive; hepatitis B core antibody positive
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 (+/-) _____.
Hepatitis B surface antigen positive; hepatitis B surface antibody negative; hepatitis B core antigen positive
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 (+/-) _____.
Hepatitis B surface antigen negative; hepatitis B surface antibody positive; hepatitis B core antibody negative
Why does hepatitis B surface antibody appear negative during the window period after hepatitis B virus infection?
Because all available hepatitis B surface antibody is bound to hepatitis B surface antigen, making it undetectable on assay
The p24gagprotein is located in the _____ (envelope/matrix/capsid) of HIV.
Capsid
Glycoproteins 41 and 120 are located in the _____ (envelope/matrix/capsid) of HIV.
Envelope
What process must occur in order for HIV genetic material to be integrated into the host genome?
Reverse transcriptase converts RNA into double-stranded DNA and it is then integrated into the host genome
What molecules does HIV bind to on T cells?
CXCR4 and CD4
What molecules does HIV bind to on macrophages?
CCR5 and CD4
People homozygous for mutations of which receptor are immune to HIV infection?
CCR5; HIV cannot invade cells without the presence of CCR5; heterozygosity leads to a slower course of illness
The p17 protein is located in the _____ (envelope/matrix/capsid) of HIV.
Matrix
Which lab technique is used to screen for HIV infection?
Enzyme-linked immunosorbent assay
Why is HIV diagnosis with enzyme-linked immunosorbent assay not considered conclusive evidence of HIV infection?
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
In diagnosing HIV, if an enzyme-linked immunosorbent assay is positive, which test is used to confirm the diagnosis?
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
Which lab technique is used to monitor response to therapy in patients who are HIV positive?
HIV polymerase chain reaction (viral load) tests allow for quantification of viral activity in the body
Both the enzyme-linked immunosorbent assay and the Western blot assay for HIV detect the presence of what molecules in serum?
Antibodies
Both the enzyme-linked immunosorbent assay and the Western blot assay are falsely negative in which group of patients?
Those who are newly infected (within first 2 months)
Both the enzyme-linked immunosorbent assay and the Western blot assay are falsely positive in which group of patients?
Babies born to infected mothers, because antibodies to anti-glycoprotein 120 can cross the placenta
The diagnosis of AIDS is made using what criteria?
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
During what two time periods does the CD4+ cell count decrease after HIV infection?
There is a decrease in CD4+ cell count during the acute phase followed by recovery and then a slow decline as the illness progresses
What is the clinical presentation of acute HIV infection?
Flu-like illness
Opportunistic infections and malignancies usually occur how long after an individual is infected with HIV?
Between 3 and 10 or more years (the immunodeficiency phase)
What are the four stages of HIV infection?
The Four Fs: Flulike (acute), Feeling fine (latent), Falling count, and Final crisis
Which AIDS-related opportunistic infections affect the brain?
Cryptococcal meningitis, toxoplasmosis, cytomegalovirus encephalopathy, AIDS dementia, progressive multifocal leukoencephalopathy (JC virus)
Which AIDS-related opportunistic infection affects the eyes?
Cytomegalovirus retinitis
Which AIDS-related opportunistic infections affect the mouth and throat?
Thrush (Candida), herpes simplex virus, cytomegalovirus, and Epstein-Barr virus (oral hairy leukoplakia)
Which AIDS-related opportunistic infections affect the lungs?
Pneumocystis jirovecipneumonia, tuberculosis, and histoplasmosis
Which AIDS-related opportunistic infections affect the gastrointestinal tract?
Cryptosporidiosis, Mycobacterium avium-intracellularecomplex, cytomegalovirus colitis, Epstein-Barr virus (as gastrointestinal lymphoma), and Isospora belli
Which AIDS-related opportunistic infections affect the skin?
Varicella zoster virus (shingles) and human herpes virus type 8 (Kaposi sarcoma)
Which AIDS-related opportunistic infections affect the genitals?
Genital herpes and human papillomavirus (genital warts, and cervical cancer)
An HIV-positive patient with a CD4+ cell count < 400/mm³ is at increased risk for
which infections?
Oral thrush, tinea pedis, reactivation of zoster, reactivation of tuberculosis, and
other bacterial infections
An HIV-positive patient with a CD4+ cell count <100/mm³ is at increased risk for which infections?
Candidal esophagitis, toxoplasmosis, and histoplasmosis
An HIV-positive patient with a CD4+ count < 50/mm³ is at increased risk for which infections?
Cytomegalovirus retinitis and esophagitis, disseminated Mycobacterium avium intracellulareinfection, and cryptococcal meningoencephalitis
An HIV-positive patient with a CD4+ cell count < 200/mm³ is at increased risk for which infections?
Pneumocystic pneumonia, reactivation of herpes simplex virus infection, cryptosporidiosis, Isosporainfection, and disseminated coccidioidomycosis
Kaposi sarcoma is caused by _____, while invasive cervical carcinoma is caused by _____.
Human herpesvirus type 8; human papillomavirus
What four malignancies are associated with HIV?
Kaposi sarcoma, invasive cervical carcinoma, primary central nervous system lymphoma and non-hodgkins lymphoma
What are the histopathologic findings of HIV encephalitis?
Microglial nodules with multinucleated giant cells
In HIV encephalitis, how does the virus gain access to the central nervous system?
Via infected macrophages
