No abstract

Viruses have been implicated in the development of neurodegenerative diseases, such as Alzheimer's, Parkinson’s, and multiple sclerosis. Human herpesvirus-6 (HHV-6) is a neurotropic virus that has been associated with a wide variety of neurologic disorders, including encephalitis, mesial temporal lobe epilepsy, and multiple sclerosis. Currently, the route of HHV-6 entry into the CNS is unknown. Using autopsy specimens, we found that the frequency of HHV-6 DNA in the olfactory bulb/tract region was among the highest in the brain regions examined. Given this finding, we investigated whether HHV-6 may infect the CNS via the olfactory pathway. HHV-6 DNA was detected in a total of 52 of 126 (41.3%) nasal mucous samples, showing the nasal cavity is a reservoir for HHV-6. Furthermore, specialized olfactory-ensheathing glial cells located in the nasal cavity were demonstrated to support HHV-6 replication in vitro. Collectively, these results support HHV-6 utilization of the olfactory pathway as a route of entry into the CNS.

Human T lymphocyte virus type I (HTLV-I)–associated chronic inflammatory neurological disease (HTLV-I–associated myelopathy/tropical spastic paraparesis [HAM/TSP]) is suggested to be an immunopathologically mediated disorder characterized by large numbers of HTLV-I Tax–specific CD8+ T cells. The frequency of these cells in the peripheral blood and cerebrospinal fluid is proportional to the amount of HTLV-I proviral load and the levels of HTLV-I tax mRNA expression. As the stimulus for these virus-specific T cells are immunodominant peptide–human histocompatibility leukocyte antigen (HLA) complexes expressed on antigen-presenting cells, it was of interest to determine which cells express these complexes and at what frequency. However, until now, it has not been possible to identify and/or quantify these peptide–HLA complexes. Using a recently developed antibody that specifically recognizes Tax11-19 peptide–HLA-A*201 complexes, the level of Tax11-19–HLA-A*201 expression on T cells was demonstrated to be increased in HAM/TSP and correlated with HTLV-I proviral DNA load, HTLV-I tax mRNA load, and HTLV-I Tax–specific CD8+ T cell frequencies. Furthermore, CD4+ CD25+ T cells were demonstrated to be the major reservoir of HTLV-I provirus as well as Tax11-19 peptide–HLA-A*201 complexes. These results indicate that the increased detection and visualization of peptide–HLA complexes in HAM/TSP CD4+ CD25+ T cell subsets that are shown to stimulate and expand HTLV-I Tax–specific CD8+ T cells may play an important role in the pathogenesis of HTLV-I–associated neurological disease.

No abstract

J. Med. Virol. 82:1669–1678, 2010. © 2010 Wiley‐Liss, Inc.

This multi-center validation study identified the lack of preparation of accurate and consistent protein standards as the main reason for a poor inter-laboratory CV. This issue is also relevant to other protein biomarkers based on this type of assay and will need to be solved in order to achieve an acceptable level of analytical accuracy. The raw data of this study is available online.

Objective Virus infections are the most common causes of encephalitis, a syndrome characterized by acute inflammation of the brain. Over 150 different viruses have been implicated in the pathogenesis of encephalitis, however due to limitations with diagnostic testing, etiologies of over half of the cases remain unknown. Methods To investigate whether HHV-6 is an etiological agent of encephalitis, we examined for evidence of virus infection by determining the presence of viral sequence using PCR and assessed HHV-6 antibody reactivity in the cerebrospinal fluids (CSF) of encephalitis patients with unknown etiology. In a cohort study, we compared virus specific antibody levels in CSF samples of patients with encephalitis, relapsing-remitting MS and other neurologic diseases (OND). Results Our results demonstrated elevated levels of HHV-6 IgG as well as IgM levels in a subset of encephalitis patients compared with OND. Moreover, cell-free viral DNA that is indicative of active infection was detected in 40% (14/35) of encephalitis patients, while no amplifiable viral sequence was found in either relapsing-remitting MS or OND patients. Additionally, a significant correlation between PCR detection and anti-HHV-6 antibody response was also demonstrated. Interpretation Collectively, these results suggested HHV-6 as a possible pathogen in a subset of encephalitis cases.

Forkhead box (Fox)/winged-helix transcription factors regulate multiple aspects of immune responsiveness and Foxp3 is recognized as an essential functional marker of regulatory T cells. Herein we describe downstream signaling pathways targeted by Foxp3 that may negatively impact retroviral pathogenesis. Overexpression of Foxp3 in HEK 293T and purified CD4+ T cells resulted in a dose-dependent and time-dependent decrease in basal levels of nuclear factor-κB (NF-κB) activation. Deletion of the carboxyl-terminal forkhead (FKH) domain, critical for nuclear localization and DNA-binding activity, abrogated the ability of Foxp3 to suppress NF-κB activity in HEK 293T cells, but not in Jurkat or primary human CD4+ T cells. We further demonstrate that Foxp3 suppressed the transcription of two human retroviral promoters (HIV-1 and human T cell lymphotropic virus type I [HTLV-I]) utilizing NF-κB-dependent and NF-κB-independent mechanisms. Examination of the latter identified the cAMP-responsive element binding protein (CREB) pathway as a target of Foxp3. Finally, comparison of the percent Foxp3+CD4+CD25+ T cells to the HTLV-I proviral load in HTLV-I-infected asymptomatic carriers and patients with HTLV-I-associated myelopathy/tropical spastic paraparesis suggested that high Foxp3 expression is associated with low proviral load and absence of disease. These results suggest an expanded role for Foxp3 in regulating NF-κB- and CREB-dependent cellular and viral gene expression.