Question 1

Viral load testing is of most clinical utility in all of the following situations EXCEPT:&#10;A) initial diagnosis of HIV infection when antibody tests are positive&#10;B) monitoring patients during antiretroviral therapy&#10;C) setting a baseline before antiretroviral therapy has begun&#10;D) investigating a patient's sudden drop in T-cell count

Accepted Answer

Viral load testing is not typically used for the initial diagnosis of HIV infection when antibody tests are positive; it is more useful for monitoring therapy, setting baselines, and investigating changes in T-cell counts.

Question 2

Which is most likely a positive Western blot result for infection with HIV?&#10;A) band at p24&#10;B) band at gp60&#10;C) bands at p24 and p31&#10;D) bands at p24 and gp120

Accepted Answer

A positive result for HIV infection on Western blot typically shows two or more bands, including one at p24 (the HIV core protein) and one at gp120 or gp160 (the envelope glycoproteins). Therefore, choice D, which includes both p24 and gp120, is the most likely positive result. Choice A (p24 alone) may be seen in early stages of infection or in individuals with advanced disease, but is not as specific for HIV. Choice B (gp60) is not a known HIV protein. Choice C (p24 and p31) may be seen in individuals with HTLV-1 infection or in some cases of HIV-2 infection.

Question 3

A 22-year-old male sees his physician for an annual checkup.He reported having flu-like symptoms including fever,sore throat,and lymphadenopathy several months ago.He has lost about 10 pounds but otherwise feels fine.Since he reports that a former girlfriend told him she is HIV positive,the physician recommends testing.An ELISA test is positive,a Western blot is positive,and a CD4+ T-cell count is 500/ $\mu$ L.What do these results indicate?

A) He has AIDS.
B) He has recovered from HIV infection.
C) He is HIV positive but in a latent stage.
D) He has an opportunistic infection and not HIV.

He is HIV positive but in a latent stage.

Accepted Answer

The positive ELISA and Western blot tests confirm that he is HIV positive. A CD4+ T-cell count of 500 indicates he is in the latent stage of HIV infection, not yet progressed to AIDS.

Question 4

All of the following body fluids are considered to be possible routes of transmission for HIV even if there is no visible sign of blood EXCEPT:&#10;A) spinal fluid&#10;B) semen&#10;C) urine&#10;D) vaginal secretions

Accepted Answer

HIV is not present in urine, so it is not considered a possible route of transmission for the virus, even if there is no visible sign of blood. However, spinal fluid, semen, and vaginal secretions are all considered possible routes of transmission for HIV, as they may contain the virus even if there is no visible sign of blood.

Question 5

What is the main mechanism of action of nucleoside analogue drugs such as zidovudine?&#10;A) inhibiting the action of reverse transcriptase&#10;B) blocking entry of HIV into host cells&#10;C) acting as protease inhibitors&#10;D) preventing release of HIV particles

Accepted Answer

Nucleoside analogue drugs such as zidovudine work by inhibiting the action of reverse transcriptase, an enzyme that is essential for the replication of HIV. These drugs mimic the structure of nucleosides, which are the building blocks of DNA and RNA. When HIV uses nucleoside analogues to build new viral DNA, the analogue disrupts the normal structure of the DNA molecule, preventing HIV from replicating effectively.

Question 6

Which test would be most reliable in detecting HIV infection in an infant younger than 18 months of age?&#10;A) ELISA test for antibody&#10;B) testing for p24 antigen&#10;C) Western blot&#10;D) DNA PCR testing

Accepted Answer

ELISA test for antibody and Western blot are not reliable in detecting HIV infection in infants younger than 18 months of age because infants born to HIV-infected mothers carry their mother's antibodies for several months, which may give false-positive test results. P24 antigen testing is more reliable than antibody testing in detecting early HIV infection, but it may not detect all cases of HIV infection in infants. DNA PCR testing, which detects the presence of HIV DNA in an infant's blood, is the most reliable test for diagnosing HIV infection in infants younger than 18 months of age, as it is not affected by the presence of maternal antibodies.

Question 7

Which technique is most widely used for the confirmation of a positive serologic assay for antibodies against HIV?&#10;A) enzyme-linked immunosorbent assay (ELISA)&#10;B) complement fixation&#10;C) Western blot assay&#10;D) polymerase chain reaction

Accepted Answer

The Western blot assay is currently the most widely used technique for confirming a positive serologic assay for antibodies against HIV. It is characterized by high specificity and sensitivity and is essential for accurate diagnosis of HIV infection. ELISA is used as a screening test for HIV infection, but it is not sufficient for definitive diagnosis. Complement fixation and polymerase chain reaction are not commonly used for the confirmation of positive serologic assays for HIV antibodies.

Question 8

What is different about the replication cycle of HIV that separates it from many other RNA viruses?&#10;A) Viral RNA is used to make cDNA.&#10;B) Viral RNA replicates itself directly to make new RNA.&#10;C) The virus reproduces only in B cells.&#10;D) Proviral DNA makes new viral particles immediately.

Accepted Answer

Unlike many other RNA viruses, HIV uses its viral RNA as a template to synthesize a complementary DNA (cDNA) strand through the action of the viral reverse transcriptase enzyme. This cDNA is then integrated into the host cell's genome, where it can remain latent or be transcribed and translated to produce new viral particles.

Question 9

A 25-year-old male presents to the public health clinic complaining of flu-like symptoms.The man has been an IV drug user and prostitute for the last 5 years.HIV antibody screening is positive.Subsequently,antibodies are found to have specificity for p24,gp120,p31,and gp41.This patient has:

A) current HIV infection
B) indeterminate HIV infection
C) lack of HIV infection
D) infection with some other virus

Accepted Answer

The presence of antibodies with specificity for p24, gp120, p31, and gp41 is highly specific for HIV infection. Additionally, the patient has a history of high-risk behaviors (IV drug use and prostitution) that increase the likelihood of HIV infection. A positive HIV antibody screening confirms the presence of HIV infection.

Question 10

A patient has serum tested for HIV antibodies by ELISA,and the test is positive.The patient's serum is retested in duplicate with two more positive results.What should be done next?&#10;A) Patient is diagnosed with acute HIV infection.&#10;B) Serum is tested for antibodies against hepatitis C virus.&#10;C) HIV Western blot assay is performed on patient's serum.&#10;D) Results mean that patient had HIV in the past but not now.

Accepted Answer

The positive ELISA test results must be confirmed by a Western blot assay, which is a more specific test for detecting HIV antibodies. This will help to rule out potential false positive results and accurately diagnose the patient's status. Testing for hepatitis C virus antibodies may be indicated depending on the patient's risk factors, but it is not necessary for confirming or ruling out HIV infection. The fact that the patient had two more positive results in duplicate suggests that the initial result was not a false positive, and further testing is needed to confirm the diagnosis. The patient may or may not have acute HIV infection, and this cannot be determined based solely on the ELISA results. Similarly, the ELISA results do not provide information about whether the patient currently has HIV or had it in the past, so answer D is incorrect.

Question 11

The HIV p24 protein encodes:&#10;A) group-specific antigen (GAG)&#10;B) the receptor for host cells (ENV)&#10;C) reverse transcriptase (POL)&#10;D) none of these

Accepted Answer

The answer of The HIV p24 protein encodes:&#10;A) group-specific antigen...

Question 12

Which of the following HIV-encoded proteins/glycoproteins is the receptor for host cells?&#10;A) p24&#10;B) gp120&#10;C) gp41&#10;D) p31

Accepted Answer

The answer of Which of the following HIV-encoded proteins/glycoproteins is...

Question 13

All of the following conditions would indicate AIDS EXCEPT:&#10;A) a CD4+ count of less than 200 cells/$\mu$L&#10;B) Kaposi's sarcoma&#10;C) esophageal candidiasis&#10;D) infectious mononucleosis

Accepted Answer

The answer of All of the following conditions would indicate...

Question 14

The Western blot test used to confirm HIV is an example of which of the following?&#10;A) immunofixation&#10;B) immunoelectrophoresis&#10;C) double diffusion&#10;D) passive agglutination

Accepted Answer

The answer of The Western blot test used to confirm...

Deck 23: Spirochete Diseases