HIV-1 phylogenetic analysis shows HIV-1 transits through the meninges to brain and peripheral tissues
Lamers SL, Gray RR, Salemi M, Huysentruyt LC, McGrath M. Infect Genet Evol 2010; Nov 3. [Epub ahead of print]
Despite what is known about the effect ofHIV in the brain, some debate exists concerning the timing of HIV entry into the central nervous system. This is the first study that used a bioinformatics approach in order to precisely identify the tissue responsible for viral transport between the brain and periphery. Frozen autopsy samples from 5 patients were used, the full gp120-nef region was sequenced and Babeysian genealogies of HIV-1 calculated...
This study identified the meninges as the primary supplier of HIV to and from the brain. Another important finding is that the brain is clearly capable of re-seeding the periphery with HIV.
The meninges contain three layers of tissue:
1-the Dura mater which is closest to the skull and a leather-like layer;
2-the Arachnoid layer which is a spider-like tissue with large blood vessels;
3-the Pia mater which is separated from the Arachnoid layer by the subarachnoid sapce, adheres to the brain and contains finer blood vessels and capillary beds. CSF flows above the Pia mater in the subarachnoid space.
The proposed model stipulates that:
-In the early infection, viruses may enter the brain due to elevated number of HIV infected macrophages in CSF related to early encephalitis;
2-Ceratin viral variants may be more suited to the brain environment and evolve in the brain, leading to a slow long-term dementia;
3-During late stage disease, lesions of the vessels of the Pia mater and subarachnoid space and breached across the BBB, allow more rapid movement of virus in and out of the brain.
Consequently, the major finding of this study in terms of reservoirs is the demonstration that HIV can migrate out of the brain.
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Key words: brain, dementia, hiv, réservoir