Herpes simplex (HSV-1) aseptic meningitis

Aseptic Meningitis in Oral Medicine: Exploring the Key Elements for a Challenging Diagnosis: A Review of the Literature and Two Case Reports

Aseptic meningitis (AM) is a potentially severe and life-threatening disease characterized by meningeal inflammation, usually with mononuclear pleocytosis. It represents a challenging and controversial issue in medicine for multiple etiologies, classification, and difficult diagnosis in the face of nonspecific sets of signs and symptoms. In the area of interest of oral medicine, in specific clusters of patients, even if rare, the occurrence of aseptic meningitis can pose a diagnostic and management dilemma in the following potential etiologies: (i) systemic diseases with oral and meningeal involvement, which include Behçet’s disease and Sjögren syndrome; (ii) drug-induced aseptic meningitis; (iii) aseptic viral meningitis, mostly related to herpes simplex virus infection and hand, foot, and mouth disease, caused by enteroviruses. In this review, clinical manifestations, diagnostic methodologies, incidence, treatment, and prognosis for each of these clinical entities are provided. Furthermore, two illustrative case reports are described: a patient suffering from recurrent oral ulcers, in which a sudden onset of AM allows us to diagnose Neuro Behçet’s disease, and a patient affected by pemphigus vulgaris, manifesting a drug-induced AM. Exploring this complex clinical entity scenario, it is clear that an oral medicine specialist has a place on any multidisciplinary team in making such a challenging diagnosis.

Synthesis and Biological Evaluation of Amidinourea Derivatives against Herpes Simplex Viruses

Current therapy against herpes simplex viruses (HSV) relies on the use of a few nucleoside antivirals such as acyclovir, famciclovir and valacyclovir. However, the current drugs are ineffective against latent and drug-resistant HSV infections. A series of amidinourea compounds, designed as analogues of the antiviral drug moroxydine, has been synthesized and evaluated as potential non-nucleoside anti-HSV agents. Three compounds showed micromolar activity against HSV-1 and low cytotoxicity, turning to be promising candidates for future optimization. Preliminary mode of action studies revealed that the new compounds act in an early stage of the HSV replication cycle, just after the viral attachment and the entry phase of the infection.

MG132 exerts anti-viral activity against HSV-1 by overcoming virus-mediated suppression of the ERK signaling pathway

Herpes simplex virus 1 (HSV-1) causes a number of clinical manifestations including cold sores, keratitis, meningitis and encephalitis. Although current drugs are available to treat HSV-1 infection, they can cause side effects such as nephrotoxicity. Moreover, owing to the emergence of drug-resistant HSV-1 strains, new anti-HSV-1 compounds are needed. Because many viruses exploit cellular host proteases and encode their own viral proteases for survival, we investigated the inhibitory effects of a panel of protease inhibitors (TLCK, TPCK, E64, bortezomib, or MG132) on HSV-1 replication and several host cell signaling pathways. We found that HSV-1 infection suppressed c-Raf-MEK1/2-ERK1/2-p90RSK signaling in host cells, which facilitated viral replication. The mechanism by which HSV-1 inhibited ERK signaling was mediated through the polyubiquitination and proteasomal degradation of Ras-guanine nucleotide-releasing factor 2 (Ras-GRF2). Importantly, the proteasome inhibitor MG132 inhibited HSV-1 replication by reversing ERK suppression in infected cells, inhibiting lytic genes (ICP5, ICP27 and UL42) expression, and overcoming the downregulation of Ras-GRF2. These results indicate that the suppression of ERK signaling via proteasomal degradation of Ras-GRF2 is necessary for HSV-1 infection and replication. Given that ERK activation by MG132 exhibits anti-HSV-1 activity, these results suggest that the proteasome inhibitor could serve as a novel therapeutic agent against HSV-1 infection.

Detection of Herpes Simplex Virus and Varicella-Zoster Virus by Traditional and Multiplex Molecular Methods

Objectives

To compare multiplex nucleic acid amplification tests (NAATs) that detect and differentiate herpes simplex virus (HSV) and varicella-zoster virus (VZV) with traditional virologic assays.

Methods

The HSV ELVIS Test System (Quidel, San Diego, CA) and/or Light Diagnostics VZV direct fluorescent antibody (DFA) kit (Millipore Sigma, Billerica, MA), as well as an ARIES HSV 1&2/VZV assay (Luminex, Austin, TX) and the Solana HSV1 + 2/VZV Assay (Quidel), were performed on non-cerebrospinal fluid specimens.

Results

The sensitivities/specificities for the ELVIS, Aries, and Solana assays for HSV were 71.1%/93.2%, 94.9%/93.2%, and 94.7%/100%, respectively. The sensitivities/specificities for the DFA, Aries, and Solana assays for VZV were 71.4%/100%, 100%/96.0%, and 95.3%/100%, respectively. HSV and VZV were detected but clinically unsuspected in 5.4% and 4.2% of the specimens, respectively.

Conclusions

Both NAAT assays were comparable and more sensitive than traditional methods. The recovery of unsuspected HSV and VZV from clinical specimens supports the implementation of a combined HSV/VZV assay.

Immune response of T cells during herpes simplex virus type 1 (HSV-1) infection

Herpes simplex virus type 1 (HSV-1), a neurotropic member of the alphaherpes virus family, is among the most prevalent and successful human pathogens. HSV-1 can cause serious diseases at every stage of life including fatal disseminated disease in newborns, cold sores, eye disease, and fatal encephalitis in adults. HSV-1 infection can trigger rapid immune responses, and efficient inhibition and clearance of HSV-1 infection rely on both the innate and adaptive immune responses of the host. Multiple strategies have been used to restrict host innate immune responses by HSV-1 to facilitate its infection in host cells. The adaptive immunity of the host plays an important role in inhibiting HSV-1 infections. The activation and regulation of T cells are the important aspects of the adaptive immunity. They play a crucial role in host-mediated immunity and are important for clearing HSV-1. In this review, we examine the findings on T cell immune responses during HSV-1 infection, which hold promise in the design of new vaccine candidates for HSV-1.

[Aseptic meningitis in an adult population. Etiology and utility of molecular techniques in the clinical management of patients]

OBJECTIVE

This study describes the epidemiological, clinical and microbiological features of acute aseptic meningitis (AAM) in an adult population, and evaluates the impact of microbiological results on the clinical management of patients.

PATIENTS AND METHODS

Cases of AAM were prospectively collected between 2007 and 2010 among immunocompetent patients over 14 years-old. Enteroviruses and herpes viruses were determined using nucleic acids detection in CSF. Demographic and clinical data were retrospectively collected from medical records.

RESULTS

A total of 94 patients were included, of whom 84 were diagnosed with viral meningitis (VM). The annual incidence of VM ranged from 2.4 to 15.3 cases per 100,000 inhabitants. An aetiological diagnosis was obtained in 76.2% of the patients with VM, 55 enterovirus, 4 HSV-2, 3 VZV, one HSV-1, and one EBV. Forty five per cent of patients were admitted to hospital and 65.8% of them received antibiotic treatment. A positive result prompted immediate discharge of 80% of inpatients and discontinuation of antibiotic therapy in 94.1% of them. The median duration of admission to hospital in these patients was 2.8±2.9 days. Patients without available results during admission completed the antibiotic treatment, and the median hospital stay was 11.6±4.6 days.

CONCLUSIONS

The annual incidence of AAM is variable. Enteroviruses were the main aetiological agent. Molecular tests revealed the aetiology in 76.2% of cases. Almost half of the patients required hospitalisation, and in these cases a positive result can lead to the immediate discharge of patients, and the diagnostic and therapeutic interventions can be reduced.

Expanding the role of 3-O sulfated heparan sulfate in herpes simplex virus type-1 entry

Heparan sulfate (HS) proteoglycans are commonly exploited by multiple viruses for initial attachment to host cells. Herpes simplex virus-1 (HSV-1) is unique because it can use HS for both attachment and penetration, provided specific binding sites for HSV-1 envelope glycoprotein gD are present. The interaction with gD is mediated by specific HS moieties or 3-O sulfated HS (3-OS HS), which are generated by all but one of the seven isoforms of 3-O sulfotransferases (3-OSTs). Here we demonstrate that several common experimental cell lines express unique sets of 3-OST isoforms. While the isoforms 3-OST-3, -5 and -6 were most commonly expressed, isoforms 3-OST-2 and -4 were undetectable in the cell lines examined. Since most cell lines expressed multiple 3-OST isoforms, we addressed the significance of 3-OS HS in HSV-1 entry by down-regulating 2-O-sulfation, a prerequisite for 3-OS HS formation, by knocking down 2-OST expression by RNA interference (RNAi). 2-OST knockdown was verified by reverse-transcriptase PCR and Western blot analysis, while 3-OS HS knockdown was verified by immunofluorescence. Cells showed a significant decrease in viral entry, suggesting an important role for 3-OS HS. Implicating 3-OS HS further, cells knocked down for 2-OST expression also demonstrated decreased cell-cell fusion when cocultivated with effector cells transfected with HSV-1 glycoproteins. Our findings suggest that 3-OS HS may play an important role in HSV-1 entry into many different cell lines.

Emergency department management of meningitis and encephalitis

Bacterial meningitis and viral encephalitis are infectious disease emergencies that can cause significant patient morbidity and mortality. Clinicians use epidemiologic, historical, and physical examination findings to identify patients at risk for these infections, and central nervous system (CNS) imaging and lumbar puncture (LP) may be needed to further evaluate for these diagnoses. The diagnosis of bacterial meningitis can be challenging, as patients often lack some of the characteristic findings of this disease with presentations that overlap with more common disorders seen in the emergency department. This article addresses considerations in clinical evaluation, need for CNS imaging before LP, interpretation of cerebrospinal fluid results, standards for and effects of timely antibiotic administration, and recommendations for specific antimicrobial therapy and corticosteroids.

Drug Insight: steroids in CNS infectious diseases--new indications for an old therapy

Infectious diseases of the CNS lead to overwhelming inflammatory processes within the brain and spinal cord that contribute substantially to patient morbidity and mortality. Pharmacological strategies to modulate inflammation have been investigated, although the resulting guidelines have sometimes been contradictory. Steroids have been proposed as adjunctive treatments for bacterial meningitis, tuberculous meningitis and herpes simplex virus encephalitis. Well-designed randomized controlled trials have established dexamethasone as an adjunctive therapy for adult patients receiving antibiotics for bacterial meningitis, and physicians prescribing the initial antibiotics need to be aware of current guidelines. Morbidity and mortality in patients with tuberculous meningitis exceeds 50%. Steroid treatments reduce mortality through an as yet unknown mechanism, although their effects on morbidity are less clear. Herpes simplex virus encephalitis is also associated with considerable morbidity and mortality. Despite a lack of randomized trials, there is some evidence that steroids used alongside antiviral therapy might be beneficial in this condition. As we discuss in this Review, systemic steroid treatment is an important aspect of treatment regimens for CNS infectious diseases, and the recent literature provides guidelines for the use of steroids in combination with appropriate antimicrobial therapy.

Listeria monocytogenes encephalitis mimicking Herpes Simplex virus encephalitis: the differential diagnostic importance of cerebrospinal fluid lactic acid levels

Listeria monocytogenes is a common cause of bacterial meningitis in elderly patients and in those with impaired cellular immunity. The most common central nervous system infection caused by L. monocytogenes is acute bacterial meningitis; meningoencephalitis is uncommon and encephalitis is rare. Early diagnosis of L. monocytogenes meningitis is difficult because only 50% of cerebrospinal fluid (CSF) Gram stains are negative. L. monocytogenes is one of the few central nervous system pathogens associated with red blood cells in the CSF. When L. monocytogenes presents as encephalitis with red blood cells in the CSF, the clinical presentation mimics most closely herpes simplex virus (HSV)-1 encephalitis. Because the therapies for L. monocytogenes and HSV-1 are different, early diagnostic differentiation is clinically important. The CSF lactic acid is the best way to rapidly differentiate between these two entities; the CSF lactic acid level is elevated in L. monocytogenes but is not elevated in HSV-1 encephalitis. The case presented is an elderly man with chronic lymphocytic leukemia who presented with encephalitis. Advanced age and chronic lymphocytic leukemia predispose him to a wide variety of pathogens, but the rapidity and severity of his clinical presentation made L. monocytogenes and HSV-1 encephalitis the most likely diagnostic possibilities. The CSF Gram stain was negative, but the elevated CSF lactic acid levels with encephalitis and red blood cells in the CSF indicated L. monocytogenes as the most likely pathogen. We present a case of L. monocytogenes encephalitis mimicking HSV-1 encephalitis. While receiving ampicillin therapy, the patient remained unresponsive for more than 1 week and then suddenly regained consciousness and recovered without neurologic sequelae.

A role for heparan sulfate 3-O-sulfotransferase isoform 2 in herpes simplex virus type 1 entry and spread

Heparan sulfate (HS) 3-O-sulfotransferase isoform-2 (3-OST-2), which belongs to a family of enzymes capable of generating herpes simplex virus type-1 (HSV-1) entry and spread receptors, is predominantly expressed in human brain. Despite its unique expression pattern, the ability of 3-OST-2 to mediate HSV-1 entry and cell-to-cell fusion is not known. Our results demonstrate that expression of 3-OST-2 can render Chinese hamster ovary K1 (CHO-K1) cells susceptible to entry of wild-type and mutant strains of HSV-1. Evidence for generation of gD receptors by 3-OST-2 were suggested by gD-mediated interference assay and the ability of 3-OST-2-expressing CHO-K1 cells to preferentially bind HSV-1 gD, which could be reversed by prior treatment of cells with HS lyases (heparinases II/III). In addition, 3-OST-2-expressing CHO-K1 cells acquired the ability to fuse with cells-expressing HSV-1 glycoproteins, a phenomenon that mimics a way of viral spread in vivo. Demonstrating specificity, the cell fusion was inhibited by soluble 3-O-sulfated forms of HS, but not unmodified HS. Taken together, our results raise the possibility of a role of 3-OST-2 in the spread of HSV-1 infection in the brain.

A role for 3-O-sulfotransferase isoform-4 in assisting HSV-1 entry and spread

Many heparan sulfate (HS) 3-O-sulfotransferase (3-OST) isoforms generate cellular receptors for herpes simplex virus type-1 (HSV-1) glycoprotein D (gD). Interestingly, the ability of 3-OST-4 to mediate HSV-1 entry and cell-to-cell fusion has not been determined, although it is predominantly expressed in the brain, a primary target of HSV-1 infections. We report that expression of 3-OST-4 can render Chinese hamster ovary K1 (CHO-K1) cells susceptible to entry of wild-type and a mutant (Rid1) strain of HSV-1. Evidence for generation of gD receptors by 3-OST-4 was suggested by gD-mediated interference assay and the ability of 3-OST-4 expressing CHO-K1 cells to preferentially bind HSV-1 gD, which could be reversed by prior treatment of cells with HS lyases (heparinases-II/III). In addition, 3-OST-4 expressing CHO-K1 cells acquired the ability to fuse with cells-expressing HSV-1 glycoproteins. Demonstrating specificity, the cell fusion was inhibited by soluble 3-O-sulfated forms of HS, but not unmodified HS. Taken together our results suggest a role of 3-OST-4 in HSV-1 pathogenesis.