Latency of herpes simplex virus type-1 in human geniculate and vestibular ganglia is associated with infiltration of CD8+ T cells.

Herpes simplex virus type-1 latency and CD8+ T-cell occurrence were investigated in the trigeminal, geniculate, and vestibular ganglia from seven deceased humans. The HSV-1 "latency-associated transcript" was assessed by in situ hybridization and quantitative RT-PCR. Infiltration of CD8+ T cell was detected by immunohistochemistry and quantitative RT-PCR. The data show that HSV-1 latency and CD8+ T-cell infiltration are not solely confined to the trigeminal ganglia but can also occur in other cranial ganglia along the neuroaxis. However, the HSV-1 latency transcripts in the geniculate and vestibular ganglia were expressed at a very low level. The difference in CD8 transcript levels among HSV-1 latently infected trigeminal ganglia, geniculate, and vestibular ganglia was less conspicuous. Colocalization of latent HSV-1 and CD8+ T cells in geniculate and vestibular ganglia supports further the hypothesis that HSV-1 reactivation is possible in these ganglia and is the cause of Bell's palsy and vestibular neuritis.

The presence of lytic HSV-1 transcripts and clonally expanded T cells with a memory effector phenotype in human sensory ganglia.

Herpes simplex virus type 1 (HSV-1) latent persistence in human trigeminal ganglia (TG) is accompanied by a chronic CD8 T-cell infiltration. Thus far, during HSV-1 latency only a single transcript, namely the latency-associated transcript (LAT), has been identified to be synthesized but not translated into a protein. In contrast, the chronic CD8 T-cell infiltration suggests that an antigen trigger must be present. The focus of the current work was to look for HSV-1 transcription activity as a potential trigger of the immune response and to demonstrate whether the immune cells are clonally expanded and have a phenotype that suggests that they have been triggered by viral antigen. By combining in situ hybridization, laser cutting microscopy, and single-cell real time RT-PCR, we demonstrated expression of the HSV-1 immediate early (IE) genes ICP0 and ICP4 in human trigeminal neurons. Using CDR3 spectratyping, we showed that the infiltrating T cells are clonally expanded, indicating an antigen-driven immune response. Moreover, the persisting CD8(+) T cells had prominent features of the memory effector phenotype. Chemokines CCL5 and CXCL10 were expressed by a subpopulation of infiltrating cells and the corresponding chemokine receptors CCR5 and CXCR3 were co-expressed on virtually all T cells bearing the CD8 phenotype. Thus, HSV-1 IE genes are expressed in human TG, and the infiltrating T cells bear several characteristics that suggest viral antigenic stimulation.

Bilateral vestibular failure as an early sign in Creutzfeldt-Jakob disease.

Bilateral vestibular failure causes dysfunction of the vestibulo-ocular reflex with consecutive symptoms like apparent movements of the visual environment during head movements (oscillopsia) and unsteady gait in darkness or on uneven ground. A definite case of Creutzfeldt-Jakob disease in which bilateral vestibular loss was one of the first clinical signs is reported. Further, in a series of 9 consecutive patients with Creutzfeldt-Jakob disease (6 probable, 3 definite), 3 had bilateral vestibular loss at initial presentation. The vestibular nuclei are known to be severely affected in animal spongiform encephalopathies. They might also be a vulnerable target in human prion diseases.

Fewer latent herpes simplex virus type 1 and cytotoxic T cells occur in the ophthalmic division than in the maxillary and mandibular divisions of the human trigeminal ganglion and nerve.

Following primary infection of the mouth, herpes simplex virus type 1 (HSV-1) travels retrogradely along the maxillary (V2) or mandibular (V3) nerve to the trigeminal ganglion (TG), where it establishes lifelong latency. Symptomatic HSV-1 reactivations frequently manifest as herpes labialis, while ocular HSV-1 disease is rare. We investigated whether these clinical observations are mirrored by the distribution of latent HSV-1 as well as cytotoxic T-cell infiltration around the nerve cell bodies and in the nerve fibers. The three divisions of the TG were separated by using neurofilament staining and carbocyanine dye Di-I tracing and then screened by in situ hybridization for the presence of HSV-1 latency-associated transcript (LAT). The T-cell distribution and the pattern of cytolytic molecule expression were evaluated by immunohistochemistry. The Di-I-labeled neurons were largely confined to the nerve entry zone of the traced nerve branches. Very few Di-I-labeled neurons were found in adjacent divisions due to traversing fiber bundles. LAT was abundant in the V2 and V3 divisions of all TG but was scarce or totally absent in the ophthalmic (V1) division. CD8(+) T cells were found in all three divisions of the TG and in the respective nerves, clearly clustering in V2 and V3, which is indicative of a chronic inflammation. Only T cells surrounding neurons in the V2 and V3 ganglionic divisions expressed granzyme B. In conclusion, the large accumulation of LAT and cytotoxic T cells in the V2 and V3 but not in the V1 division of the TG reflects the sites supplied by the sensory fibers and the clinical reactivation patterns.

The prevalence of human herpesvirus 6 in human sensory ganglia and its co-occurrence with alpha-herpesviruses.

Human herpesvirus 6 (HHV-6) persists in the central nervous system, but its prevalence in the peripheral nervous system, a preferred latency site for herpesviruses, has not been studied. Using nested polymerase chain reaction (PCR), the authors determined the distribution of HHV-6 in human sensory ganglia. HHV-6 was present in 30% of trigeminal, 40% of geniculate, 25% of vestibular, and 55% of dorsal root ganglia. It co-occurred with alpha-herpesviruses (herpes simplex virus type 1 or varicella-zoster virus) in 91% of the ganglia. As HHV-6 positivity did not depend on the presence of inflammatory cells, known to harbor the virus, HHV-6 probably resides in the ganglia themselves.

Presence of HSV-1 immediate early genes and clonally expanded T-cells with a memory effector phenotype in human trigeminal ganglia.

The latent persistence of herpes simplex virus type 1 (HSV-1) in human trigeminal ganglia (TG) is accompanied by a chronic CD8 T-cell infiltrate. The focus of the current work was to look for HSV-1 transcription activity as a potential trigger of the immune response and to characterize the immune cell infiltrates by this feature. We combined in situ hybridization, laser cutting microscopy, and single cell RT-PCR to demonstrate the expression of the HSV-1 immediate early (IE) genes ICP0 and ICP4 in human trigeminal neurons. Using CDR3 spectratyping, we showed that the infiltrating T-cells are clonally expanded, indicating an antigen-driven immune response. Moreover, the persisting CD8+ T-cells had features of the memory effector phenotype. The voltage-gated potassium channel Kv1.3, a marker of chronic activated memory effector cells, and the chemokines CCL5 and CXCL10 were expressed by a subpopulation of infiltrating cells. The corresponding chemokine receptors CCR5 and CXCR3 were co-expressed on virtually all CD8 T-cells. In addition, T-cells expressed granzymes and perforin. In contrast to animal models of HSV-1 latency, hardly any FoxP3-positive regulatory T-cells were detected in human TG. Thus, HSV-1 IE genes are expressed in human TG and the infiltrating T-cells bear several characteristics that suggest viral antigenic stimulation.

Latency of alpha-herpes viruses is accompanied by a chronic inflammation in human trigeminal ganglia but not in dorsal root ganglia.

The immune response to latent herpesvirus infections was compared in human trigeminal ganglia (TG) and dorsal root ganglia (DRG) of 15 dead individuals. On the basis of our previous findings, we hypothesized that T-cells would be attracted to sensory neurons latently infected with herpes simplex virus type 1 (HSV-1), but not to those harboring latent varicella zoster virus (VZV). We showed that the TG contain a positive hybridization signal for HSV-1 latency-associated transcript (LAT), whereas the DRG from the same individuals lack detectable LAT. In contrast, immunohistochemistry revealed that latent VZV protein 62 stained positive in the vast majority of all tested TG and DRG. T-cell infiltrates prominently surrounded individual neurons in the TG but not in the DRG. TaqMan polymerase chain reaction also showed higher expression of CD8 and RANTES transcripts in the TG versus DRG. Only the infiltrates in the TG, but not in the DRG, produced RANTES at the protein level. Because it has been shown that RANTES protein is produced only after T-cell receptor stimulation, we assume that T-cell infiltration is associated with antigen recognition in the TG but not in the DRG.

CT of the normal temporal bone: comparison of multi- and single-detector row CT.

PURPOSE: To evaluate multi- and single-detector row computed tomographic (CT) depiction of anatomic landmarks of temporal bone. MATERIALS AND METHODS: Institutional review board approval and written informed consent were obtained. In 50 temporal bones, transverse and coronal single-detector row CT images were compared with transverse and reformatted coronal multi-detector row CT images obtained of additional 50 temporal bones. Two radiologists evaluated images. Visibility of 50 landmarks was scored with a five-point quality rating scale. Fisher exact test, kappa statistics, and Mann-Whitney U test were used to evaluate imaging technique and landmark visibility. RESULTS: In delineating landmarks, total interobserver agreement was higher (P < .001) for transverse multi- than for single-detector row CT images. In 60% of landmarks, interobserver agreement was higher (P < .001) for transverse multi- than for single-detector row CT images. In 20% of landmarks, there was no difference, and in another 20% of landmarks, interobserver agreement was higher (P < .01) for single-detector row CT. Total interobserver agreement was higher (P < .01) for coronal multi-detector row reformations than for coronal single-detector row images. In 58% of landmarks, interobserver agreement was higher (P < .001) for coronal multi-detector row reformations than for coronal single-detector row images, while there was no difference in 8%. In 34% of landmarks, interobserver agreement was higher (P < .001) for coronal single-detector row images. Frequency of detected landmarks was higher for transverse (82%) and coronal (88%) multi-detector row images than for corresponding single-detector row images. In 72% of landmarks, transverse multi-detector row images were (P < .05) superior to corresponding transverse single-detector row images in landmark delineation. In 56% of landmarks, reformatted coronal multi-detector row images were (P < .05) superior to coronal single-detector row images in landmark delineation. CONCLUSION: Multi-detector row CT images, including reformations, better delineate temporal bone anatomy than do single-detector row CT images.

Methylprednisolone, valacyclovir, or the combination for vestibular neuritis.

BACKGROUND: Vestibular neuritis is the second most common cause of peripheral vestibular vertigo. Its assumed cause is a reactivation of herpes simplex virus type 1 infection. Therefore, corticosteroids, antiviral agents, or a combination of the two might improve the outcome in patients with vestibular neuritis. METHODS: We performed a prospective, randomized, double-blind, two-by-two factorial trial in which patients with acute vestibular neuritis were randomly assigned to treatment with placebo, methylprednisolone, valacyclovir, or methylprednisolone plus valacyclovir. Vestibular function was determined by caloric irrigation, with the use of the vestibular paresis formula (to measure the extent of unilateral caloric paresis) within 3 days after the onset of symptoms and 12 months afterward. RESULTS: Of a total of 141 patients who underwent randomization, 38 received placebo, 35 methylprednisolone, 33 valacyclovir, and 35 methylprednisolone plus valacyclovir. At the onset of symptoms there was no difference among the groups in the severity of vestibular paresis. The mean (+/-SD) improvement in peripheral vestibular function at the 12-month follow-up was 39.6+/-28.1 percentage points in the placebo group, 62.4+/-16.9 percentage points in the methylprednisolone group, 36.0+/-26.7 percentage points in the valacyclovir group, and 59.2+/-24.1 percentage points in the methylprednisolone-plus-valacyclovir group. Analysis of variance showed a significant effect of methylprednisolone (P<0.001) but not of valacyclovir (P=0.43). The combination of methylprednisolone and valacyclovir was not superior to corticosteroid monotherapy. CONCLUSIONS: Methylprednisolone significantly improves the recovery of peripheral vestibular function in patients with vestibular neuritis, whereas valacyclovir does not.

Prevalence and distribution of HSV-1, VZV, and HHV-6 in human cranial nerve nuclei III, IV, VI, VII, and XII.

The etiology of idiopathic cranial nerve palsies often remains unresolved. It has been hypothesised that viral reactivation of herpesviruses in the corresponding nuclei in the brainstem is the cause. We investigated the distribution of herpes simplex virus type 1 (HSV-1) and varicella zoster virus (VZV) in nuclei that are associated with peripheral sensory ganglia [oculomotor (nIII), facial (nVII) nuclei] and in nuclei that are not associated with peripheral sensory ganglia [trochlear (nIV), abducens (nVI), and hypoglossal (nXII) nuclei] of five human brainstems. Samples of the cranial nerve nuclei and adjacent control tissue were taken from histological sections after precise identification of every single nucleus and control tissue. DNA and RNA amplification methods were used to determine the prevalence and distribution of HSV-1 and VZV. The distribution of human herpes virus type 6 (HHV-6) was also determined and served as a control, since HHV-6 infection has never been associated with idiopathic cranial nerve palsies. HSV-1 was distributed at random in all cranial nerve nuclei and control tissue, whereas VZV DNA was not detected in any of the samples examined. Surprisingly, HHV-6 was present in almost all samples where HSV-1 was also present, however, the latency associated transcript (LAT) of HSV-1 was not found in any of the samples positive for HSV-1 DNA. The absence of LAT in the samples positive for HSV-1 and the distribution of HSV-1 and HHV-6 do not support the hypothesis that idiopathic cranial nerve palsies result from viral reactivation in the brainstem nuclei.

Latent herpesvirus infection in human trigeminal ganglia causes chronic immune response.

The majority of trigeminal ganglia (TGs) are latently infected with alpha-herpesviruses [herpes simplex virus type-1 (HSV-1) and varicella-zoster virus (VZV)]. Whereas HSV-1 periodically reactivates in the TGs, VZV reactivates very rarely. The goal of this study was to determine whether herpesvirus latency is linked to a local immune cell infiltration in human TGs. T cells positive for the CD3 and CD8 markers, and CD68-positive macrophages were found in 30 of 42 examined TGs from 21 healthy individuals. The presence of immune cells correlated constantly with the occurrence of the HSV-1 latency-associated transcript (LAT) and only irregularly with the presence of latent VZV protein. In contrast, uninfected TGs showed no immune cell infiltration. Quantitative RT-PCR revealed that CD8, interferon-gamma, tumor necrosis factor-alpha, IP-10, and RANTES transcripts were significantly induced in TGs latently infected with HSV-1 but not in uninfected TGs. The persisting lymphocytic cell infiltration and the elevated CD8 and cytokine/chemokine expression in the TGs demonstrate for the first time that latent herpesviral infection in humans is accompanied by a chronic inflammatory process at an immunoprivileged site but without any neuronal destruction. The chronic immune response seems to maintain viral latency and influence viral reactivation.

Dually infected (HSV-1/VZV) single neurons in human trigeminal ganglia.

Human trigeminal ganglia were tested by double fluorescence in situ hybridization for the presence and distribution of herpes simplex virus type 1 (HSV-1) and varicella-zoster virus (VZV) latency. Latency transcripts of both viruses were detected in common areas within the ganglia. Also, a few single neurons were shown to harbor HSV-1 and VZV together.