HIV US Medical PG Practice Questions and MCQs
Practice US Medical PG questions for HIV. These multiple choice questions (MCQs) cover important concepts and help you prepare for your exams.
HIV US Medical PG Question 1: A 32-year-old man comes to the physician for a follow-up examination 1 week after being admitted to the hospital for oral candidiasis and esophagitis. His CD4+ T lymphocyte count is 180 cells/μL. An HIV antibody test is positive. Genotypic resistance assay shows the virus to be susceptible to all antiretroviral therapy regimens and therapy with dolutegravir, tenofovir, and emtricitabine is initiated. Which of the following sets of laboratory findings would be most likely on follow-up evaluation 3 months later?
$$$ CD4 +/CD8 ratio %%% HIV RNA %%% HIV antibody test $$$
- A. ↓ ↓ negative
- B. ↑ ↑ negative
- C. ↓ ↑ negative
- D. ↑ ↓ positive (Correct Answer)
- E. ↓ ↑ positive
HIV Explanation: ***↑ ↓ positive***
- With effective **antiretroviral therapy (ART)**, the **CD4+/CD8 ratio** would increase as **CD4+ T cell counts rise** and **CD8+ T cell counts decrease**.
- **HIV RNA (viral load)** would significantly decrease (ideally to undetectable levels) due to the suppression of viral replication, but HIV antibodies would remain positive indefinitely.
*↓ ↓ negative*
- A decrease in the **CD4+/CD8 ratio** and **HIV RNA** (viral load) along with a negative **HIV antibody test** is inconsistent with successful ART.
- A negative HIV antibody test would mean the patient was never infected, which contradicts the initial positive result and symptoms.
*↑ ↑ negative*
- An increase in the **CD4+/CD8 ratio** is expected with ART, but an increase in **HIV RNA** (viral load) indicates treatment failure.
- A negative **HIV antibody test** is impossible after a confirmed positive result, regardless of treatment success.
*↓ ↑ negative*
- A decrease in the **CD4+/CD8 ratio** would suggest worsening immune function, while an increase in **HIV RNA** indicates treatment failure.
- A negative **HIV antibody test** is not possible once a patient has developed antibodies to HIV.
*↓ ↑ positive*
- A decrease in the **CD4+/CD8 ratio** would indicate immune decline, contrary to the expected improvement with effective ART.
- An increase in **HIV RNA (viral load)** would signify treatment failure, even if HIV antibodies remain positive.
HIV US Medical PG Question 2: A 2300-g (5-lb 1-oz) male newborn is delivered to a 29-year-old primigravid woman. The mother has HIV and received triple antiretroviral therapy during pregnancy. Her HIV viral load was 678 copies/mL 1 week prior to delivery. Labor was uncomplicated. Apgar scores are 7 and 8 at 1 and 5 minutes respectively. Physical examination of the newborn shows no abnormalities. Which of the following is the most appropriate next step in management of this infant?
- A. Administer lamivudine and nevirapine
- B. Administer zidovudine, lamivudine and nevirapine (Correct Answer)
- C. Administer nevirapine
- D. Administer zidovudine
- E. HIV antibody testing
HIV Explanation: ***Administer zidovudine, lamivudine and nevirapine***
- The mother has a **viral load of 678 copies/mL**, which falls into the **intermediate-risk category** (50-999 copies/mL) for HIV transmission.
- Current guidelines recommend **combination antiretroviral prophylaxis** (zidovudine + lamivudine + nevirapine) for infants born to mothers with viral loads in this range, typically given for 2 weeks followed by zidovudine alone to complete 4-6 weeks.
- This enhanced regimen provides better protection than monotherapy when maternal viral suppression is suboptimal.
*Administer zidovudine*
- Zidovudine monotherapy is reserved for **low-risk infants** whose mothers have viral loads **<50 copies/mL** at delivery with documented adherence to ART during pregnancy.
- With a maternal viral load of 678 copies/mL, monotherapy alone is **insufficient** and would not meet current standard of care for HIV prophylaxis.
*Administer lamivudine and nevirapine*
- This regimen omits **zidovudine**, which remains the **backbone of neonatal HIV prophylaxis** and should always be included.
- Using only lamivudine and nevirapine without zidovudine is not consistent with established guidelines.
*Administer nevirapine*
- Nevirapine monotherapy is **not adequate** for HIV prophylaxis in developed countries with access to combination therapy.
- While nevirapine may be used as a single dose in resource-limited settings, it should be part of a multi-drug regimen when other agents are available.
*HIV antibody testing*
- HIV antibody testing in newborns will detect **maternal antibodies** that crossed the placenta and cannot determine the infant's true infection status at birth.
- While HIV diagnostic testing using **PCR or viral load assays** will be performed at 14-21 days, 1-2 months, and 4-6 months of age, **antiretroviral prophylaxis must be initiated immediately** after birth to prevent transmission.
HIV US Medical PG Question 3: A 45-year-old man with a history of poorly controlled human immunodeficiency virus (HIV) infection presents to the emergency room complaining of clumsiness and weakness. He reports a 3-month history of worsening balance, asymmetric muscle weakness, and speech difficulties. He recently returned from a trip to Guatemala to visit his family. He has been poorly compliant with his anti-retroviral therapy and his most recent CD4 count was 195. His history is also notable for rheumatoid arthritis and hepatitis C. His temperature is 99°F (37.2°C), blood pressure is 140/90 mmHg, pulse is 95/min, and respirations are 18/min. On exam, he has 4/5 strength in his right upper extremity, 5/5 strength in his left upper extremity, 5/5 strength in his right lower extremity, and 3/5 strength in his left lower extremity. His speech is disjointed with intermittent long pauses between words. Vision is 20/100 in the left eye and 20/40 in his right eye; previously, his eyesight was 20/30 bilaterally. This patient most likely has a condition caused by which of the following types of pathogens?
- A. Arenavirus
- B. Bunyavirus
- C. Herpesvirus
- D. Polyomavirus (Correct Answer)
- E. Picornavirus
HIV Explanation: ***Polyomavirus***
- The patient's **poorly controlled HIV**, **low CD4 count (195)**, and progressive neurological symptoms (clumsiness, weakness, speech difficulties, vision changes) are highly suggestive of **Progressive Multifocal Leukoencephalopathy (PML)**.
- PML is caused by the **JC virus**, which is a type of **polyomavirus**, typically reactivating in immunocompromised individuals.
*Arenavirus*
- Arenaviruses (e.g., Lassa fever virus) are known to cause **hemorrhagic fevers** and can lead to neurological complications, but the clinical presentation described (progressive focal neurological deficits in an HIV patient) is not typical for an arenavirus infection.
- While some arenaviruses cause **meningoencephalitis**, the progressive, demyelinating-like course seen in this patient points away from arenavirus.
*Bunyavirus*
- Bunyaviruses (e.g., Hantavirus, La Crosse encephalitis virus) can cause **encephalitis**, fever, and myalgia, but they don't typically present with the specific constellation of **progressive white matter lesions** and focal neurological signs characteristic of PML in an HIV patient.
- Hantaviruses are more associated with **hemorrhagic fever with renal syndrome** or **hantavirus cardiopulmonary syndrome**.
*Herpesvirus*
- While herpesviruses (e.g., HSV, CMV, VZV) can cause severe neurological disease in HIV patients (e.g., **CMV encephalitis**, **HSV encephalitis**, **VZV vasculopathy**), the described progressive multifocal deficits, especially with rapid worsening, in an HIV patient with a low CD4 count strongly favor PML.
- Herpesviral encephalitides often present with more acute onset, fever, and seizures, or specific radiographic patterns not directly matching PML.
*Picornavirus*
- Picornaviruses, such as enteroviruses, can cause **aseptic meningitis** or **encephalitis**, particularly in immunocompromised individuals.
- However, the progressive, multifocal neurological deficits, particularly affecting **white matter**, are not characteristic of picornavirus infections, which tend to cause more diffuse or acute inflammatory processes.
HIV US Medical PG Question 4: A 46-year-old Caucasian male with past medical history of HIV (CD4: 77/mm^3), hypertension, hyperlipidemia, and osteoarthritis presents to the emergency department with sudden weakness of his right hand. He reports that the weakness has gradually been getting worse and that this morning he dropped his cup of coffee. He has never had anything like this happen to him before, although he was hospitalized last year for pneumonia. He reports inconsistent adherence to his home medications, which include raltegravir, tenofovir, emtricitabine, TMP-SMX, hydrochlorothiazide, pravastatin, and occasional ibuprofen. His father died of a myocardial infarction at the age of 60, and his mother suffered a stroke at the age of 72. The patient's temperature is 102.6°F (39.2°C), blood pressure is 156/92 mmHg, pulse is 88/min, and respirations are 18/min. On neurological exam, he has 3/5 strength in the distal muscles of the right extremity with preserved sensation. His neurological exam is normal in all other extremities.
Which of the following is the best next step in management?
- A. Serology for Toxoplasma-specific IgG antibodies
- B. Empiric treatment with pyrimethamine-sulfadiazine
- C. Head CT (Correct Answer)
- D. Empiric treatment with itraconazole
- E. Lumbar puncture
HIV Explanation: ***Head CT***
- The patient presents with **focal neurological deficits** (right hand weakness) and has several risk factors, including poorly controlled **HIV with a low CD4 count** (increased risk of opportunistic infections or CNS lesions) and uncontrolled hypertension (increased risk of stroke). A **head CT** is crucial to rapidly identify potential causes like a mass lesion, hemorrhage, or infarct, which would guide immediate management.
- The **fever** and **subacute onset** of weakness (gradually worsening with acute exacerbation) also point towards an intracranial process that needs urgent imaging.
*Serology for Toxoplasma-specific IgG antibodies*
- While **Toxoplasmosis** is a strong consideration given the patient's low CD4 count, **serology alone is not the best initial step** for acute neurological deficits.
- A positive IgG indicates past exposure but not necessarily active infection, and it doesn't provide real-time information on the cause of the focal neurological symptoms. Imaging is needed first to identify a lesion.
*Empiric treatment with pyrimethamine-sulfadiazine*
- This is the treatment for **cerebral toxoplasmosis**, but **empiric treatment should only be initiated after imaging** (CT or MRI) confirms the presence of a lesion consistent with toxoplasmosis, especially in a patient with acute focal deficits.
- Starting treatment without imaging may delay diagnosis of other potentially critical conditions like a brain abscess, lymphoma, or stroke.
*Empiric treatment with itraconazole*
- **Itraconazole** is an antifungal medication, typically used for histoplasmosis, blastomycosis, or aspergillosis, which are less common causes of acute focal neurological deficits in HIV than toxoplasmosis or lymphoma.
- There is no specific clinical indication or risk factor (e.g., endemic area for fungal infections) that would make **empiric antifungal treatment** the best next step compared to diagnostic imaging for this presentation.
*Lumbar puncture*
- A **lumbar puncture** can be useful in diagnosing CNS infections (e.g., cryptococcal meningitis, viral encephalitis) or other inflammatory conditions, but it is typically performed *after* ruling out a mass lesion or increased intracranial pressure with imaging (CT or MRI) to prevent herniation.
- Given the patient's focal neurological deficit and potential for a mass or hemorrhage, **LP carries a risk of brain herniation** and is not the best initial step.
HIV US Medical PG Question 5: A physician scientist is looking for a more efficient way to treat HIV. Patients infected with HIV mount a humoral immune response by producing antibodies against the HIV envelope proteins. These antibodies are the same antibodies detected by the ELISA and western blot assays used to diagnose the disease. The physician scientist is trying to generate a new, more potent antibody against the same HIV envelope proteins targeted by the natural humoral immune response. Of the following proteins, which is the most likely target of the antibody he is designing?
- A. p24
- B. CXCR4
- C. CCR5
- D. p17
- E. gp120 (Correct Answer)
HIV Explanation: ***gp120***
- **gp120** is an **envelope glycoprotein** on the surface of HIV, responsible for binding to CD4 receptors on host cells.
- Antibodies against **gp120** are generated during natural infection and are detected by diagnostic assays, making it a primary target for therapeutic antibody development.
*p24*
- **p24** is a **capsid protein** of HIV, forming the conical core of the virus, but it is not an envelope protein.
- While antibodies against **p24** are produced during infection and are detectable, it's an internal protein, not exposed on the viral surface for direct neutralization.
*CXCR4*
- **CXCR4** is a **chemokine co-receptor** found on the surface of host cells (e.g., T-lymphocytes), used by some HIV strains (T-tropic) for entry.
- It is a host cell protein, not an HIV viral protein, so it would not be a target for antibodies aiming to directly neutralize the virus.
*CCR5*
- **CCR5** is another **chemokine co-receptor** on host cells (e.g., macrophages, T-lymphocytes) used by other HIV strains (M-tropic) for viral entry.
- Similar to CXCR4, it is a host cell protein, not an HIV envelope protein, and therefore not a direct target for neutralizing antibodies against the virus itself.
*p17*
- **p17** is an HIV **matrix protein** located just beneath the viral envelope, playing a role in viral assembly and budding.
- Similar to p24, it is an internal structural protein, not an external envelope protein, making it less accessible for neutralizing antibodies.
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