A 54-year-old man is brought to the office by his friend because of worsening memory impairment over the past several months. The patient is also withdrawn and not focused during conversations. He is slow to answer questions or carry out instructions. The patient has a prolonged history of HIV infection and has had several opportunistic infections due to inconsistent antiretroviral medication use. On physical examination, he is alert and oriented. Muscle strength, deep tendon reflexes, and sensation are normal. MRI of the head shows diffuse cerebral atrophy with no focal mass lesions or areas of demyelination. Viral proliferation in which of the following central nervous system cells is most likely involved in this patient's disease process?

Question

A 54-year-old man is brought to the office by his friend because of worsening memory impairment over the past several months.  The patient is also withdrawn and not focused during conversations.  He is slow to answer questions or carry out instructions.  The patient has a prolonged history of HIV infection and has had several opportunistic infections due to inconsistent antiretroviral medication use.  On physical examination, he is alert and oriented.  Muscle strength, deep tendon reflexes, and sensation are normal.  MRI of the head shows diffuse cerebral atrophy with no focal mass lesions or areas of demyelination.  Viral proliferation in which of the following central nervous system cells is most likely involved in this patient's disease process?

Quizplus · Accepted Answer

In the context of a long history of HIV infection, this patient's memory impairment, subcortical dysfunction (ie, inattention, impaired psychomotor speed), and cerebral atrophy on MRI of the head are consistent with HIV-associated dementia (HAD). HAD is characteristically a subcortical dementia with prominent mood, attention, memory, and psychomotor dysfunction. It is uncommon in patients receiving antiretroviral treatment but can occur in those with inconsistently treated, advanced HIV infection. Although HIV-1 preferentially infects and replicates in CD4⁺ helper T cells in peripheral blood (Choice A), CNS infection is associated with a change in viral tropism (ie, ability to infect different cell types) to microglia and macrophages, which allows the virus to penetrate deeper into the brain parenchyma. This macrophage tropic (M-tropic) version of the virus becomes "compartmentalized" in the CNS and evolves independently from the strain found in the blood. (Choices B and E) HIV is not neuron or oligodendrocyte tropic. Viruses that are neuron tropic include the lyssaviruses that cause rabies. (Choice C) HIV does not preferentially infect and replicate in endothelial cells in the CNS. Cytomegalovirus is an example of an endothelial cell-tropic virus. Educational objective: HIV-associated dementia has become rare since the advent of antiretroviral treatment but may still develop in patients with inadequately treated, late-stage HIV infection. In the CNS, HIV preferentially infects and replicates in macrophages. __________ References: Macrophage cell-cell interactions promoting HIV-1 infection. (http://www.ncbi.nlm.nih.gov/pubmed/32354203)

A 54-Year-Old Man Is Brought to the Office by His