The abundant latency-associated transcripts of herpes simplex virus type 1 are bound to polyribosomes in cultured neuronal cells and during latent infection in mouse trigeminal ganglia

During herpes simplex virus type 1 (HSV-1) latency, limited viral transcription takes place. This transcription has been linked to the ability of the HSV-1 genome to reactivate and consists of abundant 2.0- and 1.5-kb collinear latency-associated transcripts (LATs), spanned by minor hybridizing RNA (mLAT). The 1.5-kb LAT is derived from the 2.0-kb LAT by splicing, and both transcripts contain two large overlapping open reading frames. The molecular action mechanisms of the latency-associated gene expression are unknown, and no HSV-1 latency-encoded proteins have been convincingly demonstrated. We have cloned the entire latency-associated transcriptionally active HSV-1 DNA fragment (10.4 kb) under control of a constitutive promoter and generated a neuronal cell line (NA4) stably transfected with the viral LAT's region. NA4 cells produced the 2.0- and the 1.5-kb LATs. Northern blotting and reverse transcription-PCR analysis of RNA from NA4 cells and from trigeminal ganglia of mice latently infected with HSV-1 revealed that the two abundant LAT species were present in the polyribosomal RNA fractions. After addition of EDTA, which causes dissociation of mRNA-ribosome complexes, both LATs could be detected only in subpolyribosomal, but not in polyribosomal fractions. These results show that (i) HSV-1 LATs are bound to polyribosomes during latency in vivo, as well as in neuronal cells in vitro, and therefore might be translated, and that (ii) the NA4 cell line is a suitable tool with which to look for HSV-1 latency-encoded gene products.

Neocortical temporal lobe sclerosis masquerading as Alzheimer dementia: does herpes virus encephalopathy protect against Alzheimer's disease?

Semi-quantitative neuropathological analysis and morphometric evaluations of the brains of 5 elderly people (63-85 years old) dying following a 5-27-year history of dementia reveal that, despite exhaustive survey of all major brain regions, 4 of these cases show virtually no histopathological lesions of Alzheimer's disease. Instead their CNS manifests a severe, bilateral, neuronal depletion, and astrogliosis afflicting the lateral temporal neocortex, highly compatible with a previous herpetic viral encephalitis. In the fifth case unilateral neocortical temporal lobe sclerosis is accompanied by Alzheimer's disease, but with much more dense Alzheimer lesions throughout the contralateral cerebral hemisphere. Three of these 5 individuals had a history either of herpes zoster of the skin or of a single episode of viral meningoencephalitis, roughly concomitant with the onset of memory loss. This clinical and pathological evidence that a remote herpes virus encephalopathy (when bilateral) "protects" that brain against Alzheimer's disease strengthens our growing suspicion that incomplete replication cycles of herpes simplex or zoster virus, following repeated reactivation within neurons of the trigeminal ganglia, may link these viruses to the pathogenetic cascade underlying dementia of the Alzheimer type.

Serum Cu/Zn superoxide dismutase activity is reduced in sporadic amyotrophic lateral sclerosis patients

Accumulated evidence implies that mutations in the gene coding for Cu/Zn superoxide dismutase (SOD) are associated with the pathogenesis of the familial form of amyotrophic lateral sclerosis (ALS). The clinical and pathological similarities of the familial and the sporadic forms of the disease may suggest that abnormal SOD activity takes also part in the pathogenesis of sporadic ALS. We therefore measured serum SOD activity in fifteen sporadic ALS patients. Mean serum SOD activity was 1.15 +/- 0.40 u/ml in ALS patients, 1.50 +/- 0.45 u/ml. in patients with other neurological disorders and 1.45 +/- 0.45 u/ml in.healthy controls (p < 0.021 and p < 0.031 respectively). If this sporadic ALS-related reduction in serum SOD activity will be confirmed in the diseased nervous system tissue, it may suggest that abnormal SOD activity is also associated with the motor neuron damage in the sporadic form of ALS.

Human herpes viruses latent infection in the nervous system

The neurotropic herpes viruses, HSV-1, HSV-2 and VZV, colonize and establish latent infection in human peripheral sensory ganglia. Recurrent diseases due to reactivation of these viral pathogens can take place despite an effective immune response. Molecular, cellular, physiological and immune mechanisms work in concert to enable the establishment of latency, the maintenance of the latent state for the entire life of the host, and the reactivation infection. Although all three viruses belong to the same family and establish latent infection in the same tissue, the clinical pattern of their reactivation is quite different. This review covers current knowledge of the basis of these infections, and offers a theory explaining the basis of HSV-1 latent infection and the differences of the disorders caused by HSV-1 and VZV reactivation in humans.

Unilateral proptosis due to cerebellar stroke

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Expression and splicing of the latency-associated transcripts of herpes simplex virus type 1 in neuronal and non-neuronal cell lines

Herpes simplex virus type 1 (HSV-1) is transcriptionally active during latent infection in human peripheral sensory ganglia. This transcription has been linked to the ability of the virus to reactivate, but its potential gene products and mechanisms of action are unknown. To analyze the viral latency-related transcripts in neuronal and non-neuronal cell lines in an isolated cellular system, a 10.4 kb DNA fragment, which covers the entire viral transcriptionally active latency-associated region, was cloned under control of the constitutive cytomegalovirus promoter (pNM3). During transient transfection of a human embryonic kidney 293 cell line, pNM3 expressed high levels of the 2.0 kb latency-associated transcript (LAT) that was not polyadenylated. The 1.5 kb LAT as well as the minor hybridizing RNAs could not be identified by Northern blotting analysis. pNM3 expression was further analyzed following transfection of two neuronal, C1300 and ND7 cell lines. The 2.0 kb LAT was synthesized at high levels in these cell lines. The 1.5 kb LAT, which in vivo can be identified only during HSV-1 latent infection in tissues which facilitate reactivation, was present at very low amounts in 293 and C1300 cells using reverse transcription PCR analysis. Higher amounts of the 1.5 kb LAT were produced in ND7 cells, a neuronal cell line shown to possess neuronal-specific splicing proteins. However, the 1.5 kb LAT was present in ND7 cells in lesser amounts than produced during latent infection in peripheral sensory ganglia. This novel cellular system provides now a tool for future studies of the role of the 1.5 kb and the 2.0 kb LATs in HSV-1 latency.

Neurologic aspects of inflammatory bowel disease

To determine the frequency, spectrum, and clinical features of neurologic disorders associated with ulcerative colitis (UC) and Crohn's disease (CD).

BACKGROUND

Extraintestinal manifestations of inflammatory bowel disease (IBD) are well documented, but the association of IBD with neurologic involvement is rare and often controversial.

METHODS

Tertiary care center ambulatory and hospital services data bank retrospective computerized search with subsequent file review.

PATIENTS

From among 638 IBD patients diagnosed from 1981 to 1991, we identified 10 CD patients and nine UC patients with neurologic involvement unrelated to a defined systemic or iatrogenic cause. Neurologic disorders diagnosed 15 or more years before the intestinal symptomatology were excluded.

RESULTS

Three percent of IBD patients had neurologic involvement. In 14 of 19 (74%), it started within a mean of 5.7 years (range, 0.7 to 12 years) after the diagnosis of bowel disease, and in two of 19 (10%) it occurred at the time of IBD exacerbation. During the course of IBD, 10 of 19 patients (53%) exhibited other extraintestinal manifestations. Peripheral nerve disorders were observed in six UC patients. Myelopathy (5 patients), myopathy (3), and myasthenia gravis (1) were diagnosed in eight CD patients and one UC patient. Cerebrovascular disorders occurred in two UC and two CD patients.

CONCLUSIONS

Neurologic disorders associated with IBD are more common than appreciated and follow a different pattern of involvement in UC and CD. A prospective study is required to define the nature of this association.

Herpes simplex virus latent infection in the nervous system

Herpes simplex virus (HSV) establishes a latent infection in the human peripheral nervous system and can cause recurrent disease by reactivation. Intensive effort has been directed in recent years to unveil the molecular, cellular and immune mechanisms, as well as the virus-host interactions associated with latent HSV infection. The aim of this review is to summarize current knowledge regarding the site of latent infection, the molecular phenomena of latency, and the mechanisms of the various stages of HSV-1 latent infection in the nervous system, relating them where possible to the human situation. Specifically, the following biological questions are addressed: (1) How does this lytic virus survive in the nervous system and why can it establish a lifelong latent infection in nerve cells? (2) What advantage is conferred on HSV by establishing latent infection in nervous tissue? (3) What can be gathered from the accumulated knowledge on latency about the pathogenesis of herpes simplex encephalitis?

[Endoluminal grafts in the therapy of aneurysms of the abdominal aorta. Experimental results]

In 1991 a new method of treatment of aneurysms of the abdominal aorta was published. The method is based on bridging the sac of the aneurysm by an endoluminal graft. The graft is a stent provided with a special vascular prosthesis. The endoprosthesis is inserted by means of a catheter from arteriotomy of the common femoral artery. The objective of the submitted work was to test the possibility to use a polyester covered spiral Z stent in the treatment of aneurysms of the abdominal aorta. For experiments six dogs were used weighing 12-18 kg. In the experimental animals an artificial aneurysm of the abdominal aorta was induced. Then the authors interposed surgically into the subrenal section of the abdominal aorta a special polyester knitted prosthesis imitating the shape of the aneurysm. Two weeks after surgery angiography of the abdominal aorta was performed. After angiography the authors introduced from arteriotomy of the superficial femoral artery an endoluminal graft into the artificial aneurysm. The graft bridged the aneurysm on the inside and this led to thrombosis of the sac of the aneurysm. The state of the graft and aneurysm was checked sonographically and angiographically. The graft was successfully used in all experimental animals. Angiographic check-up examinations revealed that application of the graft led to immediate exclusion of the sac of the aneurysm. In two experimental animals the graft was inserted in an excessively cranial position. It did not bridge the aneurysm throughout its length. Reflux of blood in the distal part persisted and filled the residual cavity of the sac of the aneurysm.(ABSTRACT TRUNCATED AT 250 WORDS)

A molecular and cellular model to explain the differences in reactivation from latency by herpes simplex and varicella-zoster viruses

There are marked similarities in the biological properties of the human neurotropic herpesviruses herpes simplex virus type 1 (HSV-1) and varicella-zoster virus (VZV), including their ability to establish lifelong latent infections in human peripheral sensory ganglia (PSG). Despite this, their patterns of reactivation are quite different: HSV-1 reactivations occur many times during a lifetime, they are localized to the cutaneous distribution of a single sensory nerve, they are not associated with sensory symptomatology and their frequency decreases with age. VZV recurrence on the other hand is usually a single event which tends to appear with advancing age, its cutaneous eruption involves an entire dermatome and is usually extremely painful. To help explain these differences, we have formulated a model based on current knowledge of the molecular and cellular basis of latent infection in the nervous system. We suggest that the amount of latent viral DNA and RNA in the latently infected tissue (higher with HSV-1), the cellular location of latent virus (neuronal in HSV-1, probably non-neuronal in VZV), the presence or absence of viral replication in the PSG during reactivation together with the host immune response, are all key determinants of the clinical expression of viral reactivation.

Herpes simplex virus type 1 gene expression and reactivation of latent infection in the central nervous system

Restricted gene expression takes place during latent infection of herpes simplex virus type 1 (HSV-1) in the human peripheral nervous system and has been linked with viral reactivation. The state of HSV-1 gene expression in the central nervous system (CNS) during latency is unclear and we, therefore, examined gene expression in the brainstem of experimental mice and normal humans. Only part of the transcription pattern present during latent infection in peripheral sensory ganglia (PSG) was identified in the human brainstem by in situ hybridization and Northern blot analysis for HSV-1-specific transcripts. Instead of three HSV-1 latency-associated transcripts (LATs) present in PSG and demonstrated by Northern blot analysis, only one was identified in mouse brainstem and none was detected in human brainstem. These findings might be attributed to the relatively low amounts of HSV-1-specific latency-associated RNAs in brainstem tissue. Combined with our inability to reactivate HSV-1 from explanted mouse brainstem, these findings suggest that tissue levels of latency-associated gene expression play a role in HSV-1 reactivation and have relevance to the very low incidence of HSV-1-induced CNS disease compared with peripheral mucocutaneous disease.

[Infectious endocarditis--a study of 153 cases]

The study describes 153 necropsy cases of infective endocarditis (IE) encountered in a university hospital over a period of 23 years (1970-1992), with necropsy incidence of 0.63%. The average age of patients at the time of death was 51.7 years. Both the incidence and the average age tended to increase during the period studied. The location of infective vegetations was mostly in the left heart and univalvular (mitral in 41%, aortic in 33%). The mitral valves involved by IE were otherwise normal in 62%; the aortic valves were normal in 33%. The spectrum of microorganisms yielded by postmortem cultivations is compared with that obtained by blood cultures during life. Staphylococcus aureus comprised 60% of all positive clinical blood cultures and 40% of all organisms grown postmortally. Gram-negative bacilli, streptococci and mycoses appeared as further important etiologic agents. Discussed in more detail are the subgroups of tricuspid valve IE (5% of all cases), IE in patients on chronic hemodialysis (17%), and IE involving prosthetic valves (9%).

Evidence for intrathecal synthesis of autoantibodies in systemic lupus erythematosus with neurological involvement

The diagnosis of systemic lupus erythematosus (SLE) in a patient who presents with isolated central nervous system (CNS) abnormalities, is a difficult clinical challenge. The pathogenesis of such CNS involvement in SLE is unknown. Twelve patients with active SLE were examined for serum and cerebrospinal fluid (CSF) autoantibodies and compared with 21 patients with headache. Four of six patients with SLE and active CNS presentation had CSF autoantibodies while none of the other SLE patients and the controls had autoantibodies. We describe these four patients in whom immunological work-up revealed CSF antinuclear, anti-DNA, anti-SSA/Ro, anti-SSB/La and antineuronal autoantibodies. A newly devised antibody activity index provided means to demonstrate that the CSF autoantibodies in these patients were produced intrathecally. Beyond the importance of our finding of the potential role of autoantibodies in the pathogenesis of CNS damage in SLE, we propose that CSF analysis for autoantibodies should become an essential part of the diagnostic work-up in autoimmune diseases with CNS involvement.

The use of herpes simplex virus vectors for gene therapy in neurological diseases

Herpes simplex virus type 1 (HSV-1) vectors have now been developed and enable the efficient delivery of foreign genes under the control of appropriate promoter elements into non-dividing neurons in vitro and in vivo. Their use is based on the natural ability of HSV-1 to spread throughout the nervous system and to establish a lifelong latent infection in neurons. HSV is present in an episomal form in the neuronal nucleus, and normal neuronal functions remain unaltered. A wide variety of foreign genes can theoretically be packaged into the large HSV genome. A number of technical problems will need to be overcome to ensure the stable expression of the foreign gene products, adequate control of the levels of their expression, the safety of the vectors and the correct targeting of the vectors to the appropriate neuronal cell populations. Such vectors have the potential to replace missing gene products in neurons in patients with a variety of metabolic and neurodegenerative diseases, and also to insert growth factors or enzymes into the local vicinity of neurological lesions to promote neuronal repair. HSV-1 vectors also have the potential to define the genetic basis of various neurophysiological functions which may prove to be useful in evaluating altered neuronal function encountered in disease.

Characterization of an in vivo reactivation model of herpes simplex virus from mice trigeminal ganglia

Herpes simplex virus type 1 (HSV-1) is transcriptionally active during latent infection in human peripheral sensory ganglia. Viral gene expression includes the latency-associated transcripts (LATs) which have been linked to the ability of the virus to resume replication and reactivate. However, the molecular basis of reactivation and the mechanisms of action of these transcripts are unknown. In order to study these parameters, an in vivo reactivation model is needed. We investigated use of the mouse as the experimental animal, modifying the route of infection, the viral strain and the reactivation protocol. Following administration of human immunoglobulin 1 day prior to corneal infection, no infectious virus was detected in trigeminal ganglia (TG). However, latency was established in all infected animals as indicated by explant reactivation of TG, and in vivo reactivation was achieved in 30 to 40% of them. DNA quantification revealed that TG of immunized mice contained more HSV-1 DNA than did those of non-immunized mice. By in situ hybridization twice as many neuronal cells in TG of immunized mice were positive for LATs, compared with infected but non-immunized, mice. These findings suggest that suppression of primary infection facilitates reactivation by increasing HSV-1 copy number in latently infected nervous tissue.