Final Answer:
HIV enter the CNS through infiltration of infected immune cells such as monocytes and lymphocytes. Therefor, the correct option is 1) Through infiltration of infected immune cells such as monocytes and lymphocytes.
Step-by-step explanation:
HIV can breach the Central Nervous System (CNS) primarily through the infiltration of infected immune cells like monocytes and lymphocytes. These immune cells can act as carriers, crossing the blood-brain barrier (BBB) and introducing the virus into the CNS. The blood-brain barrier normally serves as a protective barrier, regulating the passage of substances into the brain. However, infected immune cells, especially monocytes, can exploit their ability to traverse the BBB, carrying the HIV virus into the CNS.
Once HIV enters the bloodstream, infected monocytes or lymphocytes can traverse the BBB via a process known as "Trojan horse" penetration. These infected immune cells use adhesion molecules and chemokine receptors to cross the BBB and release HIV within the CNS. This infiltration into the brain parenchyma allows the virus to establish reservoirs within the central nervous system, contributing to neuroinflammation and potential neurological complications associated with HIV infection.
Although other mechanisms like paracellular or transcellular migration have been proposed, the predominant route for HIV entry into the CNS involves infected immune cells breaching the blood-brain barrier, highlighting the significance of understanding the interplay between the immune system and the CNS in HIV pathogenesis. Therefor, the correct option is 1) Through infiltration of infected immune cells such as monocytes and lymphocytes.