HIV-1 infection of the central nervous system (CNS) results in neurological impairments in subpopulation of HIV-infected individuals which range from from mild cognitive/motor disorder (MCMD) to HIV-associated dementia (HAD). HIV-1 associated neurological diseases are still a big problem even with the introduction of combined antiretroviral therapy. However the mechanisms of CNS infection and pathogenesis that lead to HAD are still not completely clear. HIV-1 CNS infection occurs soon after peripheral infection. Subsequent to infection, the CNS may act as a protected anatomical reservoir for lentiviruses and may also give rise to the development of or sequestration of unique quasispecies. The choroid plexus (ChP) has been demonstrated to be an important site for lentivirus infection and contains a mixture of viral quasispecies including both systemic and brain derived isolates. Since the appearance of viral RNA is particularly prominent in the cerebrospinal fluid (CSF), the ChP-CSF pathway may contribute to infection and viral diversity in the CNS. In the present study, we investigated lentiviral infection and evolution within the CNS by directly infusing virus into the CSF using an FIV animal model. Cell-free NCSU1 FIV or cell-associated FIV (FIV infected ChP macrophages) was directly injected into the right lateral ventricle of the brain. Negative controls were sham inoculated with uninfected ChP macrophages or cell-free culture supernatant and positive controls were infected systemically with cell-free FIV by intraperitoneal (i.p.) injection. Intracerebroventricular (i.c.v.) inoculation with cell-free FIV resulted in high levels of plasma FIV RNA detected as early as 1-2 weeks post inoculation in all 6 i.c.v. cats, and the plasma viremia preceded the detection of CSF viral RNA. Compared to i.p. cats, i.c.v. cats exhibited much higher levels of CSF FIV RNA and FIV DNA in the brain, increased ratios of CSF to plasma viral load (>1 at several time points), and a unique rebound CSF viral peak (5 of 6 cats). Infusion of FIV-infected ChP-Mac induced an acute inflammatory response and a slight suppression of the CD4+:CD8+ ratio, but failed to produce a detectable infection. After cell-free inoculation, FIV env variants, amplified by the poymerase chain reaction (PCR) and isolated using the heteroduplex tracking assay (HTA), exhibited clear compartmentalization between the CNS and periphery. Unique or enriched variants rapidly appeared in the CSF. Similar variation was seen in FIV proviral DNA isolated from cortical and subcortical brain regions. Compared to the initial viral peak in CSF, the second CSF viral peak displayed considerable change from both the first CSF peak and matched samples of plasma. FIV env diversity was highest in the CNS tissue and was unrelated to matched PBMCs collected at the same time indicating that the sequences were not due to PBMC trafficking. In addition, three unique variants were found to be selectively enriched in the CNS. Taken together, these results demonstrated that 1) CSF provides an efficient pathway for the transfer of infectious virus to the periphery, 2) virus trafficking through the CSF promotes infection of the CNS and viral diversification, 3) CSF virus may derive from both the local productive infection and blood, and 4)virus within the CNS experienced a relatively rapid and independent evolution relative to virus in the periphery.
| Identifer | oai:union.ndltd.org:NCSU/oai:NCSU:etd-10302005-212859 |
| Date | 09 November 2005 |
| Creators | Liu, Pinghuang |
| Contributors | Lola C. Hudson, Mary B. Tompkins, Frederick J. Fuller, Rick B. Meeker |
| Publisher | NCSU |
| Source Sets | North Carolina State University |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://www.lib.ncsu.edu/theses/available/etd-10302005-212859/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to NC State University or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
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