Question

What is correct about the "Trojan Horse" model of HIV invasion into the CNS? a. Proposes that monocyte-macrophage carry progeny virions from blood to the brain inside cytoplasmic vacuoles and across the blood-brain barrier b. Requires an inflammatory response in the brain, which elicits a chemokine gradient c. After infiltrating the brain parenchyma, blood borne monocyte-macrophages also release additional chemokines and further attract additional inflammatory cells d. Does not require productive viral replication in brain microvascular endothelial cells e. All of the above

Short answer

A. The model proposes that monocyte-macrophages carry progeny virions from the blood to the brain inside cytoplasmic vacuoles and across the blood-brain barrier. B. The Trojan Horse model requires an inflammatory response in the brain, eliciting a chemokine gradient. C. After infiltrating the brain parenchyma, blood-borne monocyte-macrophages also release additional chemokines and further attract additional inflammatory cells. D. The Trojan Horse model does not require productive viral replication in brain microvascular endothelial cells. E. All of the above. Answer: E. All of the above.

Step-by-step solution

Understand the Trojan Horse Model of HIV Invasion into the CNS

The Trojan Horse model describes how HIV enters the central nervous system (CNS) by using monocyte-macrophages as carriers, which cross the blood-brain barrier and deliver the virus into the CNS.

Evaluate Option A

Option A states that this model proposes monocyte-macrophages carry progeny virions from the blood to the brain inside cytoplasmic vacuoles and across the blood-brain barrier. This is in line with the Trojan Horse model, as it highlights the role of monocyte-macrophages in HIV invasion into the CNS.

Evaluate Option B

Option B states that the Trojan Horse model requires an inflammatory response in the brain, eliciting a chemokine gradient. This is also correct because the inflammatory response is necessary for monocyte-macrophages to be attracted to the site of infection and subsequently infiltrate the CNS.

Evaluate Option C

Option C says that after infiltrating the brain parenchyma, blood-borne monocyte-macrophages also release additional chemokines and further attract additional inflammatory cells. This is true, as it adds to the inflammatory reaction and allows the spread of the infection within the CNS.

Evaluate Option D

Option D claims that the Trojan Horse model does not require productive viral replication in brain microvascular endothelial cells. This is also correct, as the primary focus of the model is on the role of monocyte-macrophages carrying the virus, rather than viral replication within the CNS.

Choose the Correct Answer

Since all options A, B, C, and D are consistent with the Trojan Horse model of HIV invasion into the CNS, the correct answer is option E, which states that all of the above are correct.