SciCombinator

Discover the most talked about and latest scientific content & concepts.

Concept: Encephalitis

260

Previous experimental studies have demonstrated that a number of mosquito-borne flavivirus pathogens are vertically transmitted in their insect vectors, providing a mechanism for these arboviruses to persist during adverse climatic conditions or in the absence of a susceptible vertebrate host. In this study, designed to test whether Zika virus (ZIKV) could be vertically transmitted, female Aedes aegypti and Aedes albopictus were injected with ZIKV, and their F1 adult progeny were tested for ZIKV infection. Of 69 Ae. aegypti pools, six consisted of a total of 1,738 F1 adults, yielded ZIKV upon culture, giving a minimum filial infection rate of 1:290. In contrast, none of 803 F1 Ae. albopictus adults (32 pools) yielded ZIKV. The MFIR for Ae. aegypti was comparable to MFIRs reported for other flaviviruses in mosquitoes, including dengue, Japanese encephalitis, yellow fever, West Nile, and St. Louis encephalitis viruses. The results suggest that vertical transmission may provide a potential mechanism for the virus to survive during adverse conditions.

Concepts: Encephalitis, Dengue fever, Yellow fever, Flaviviridae, Aedes aegypti, Flaviviruses, Mosquito, Aedes

174

BACKGROUND: The morphogenesis of herpes simplex virus type 1 (HSV-1) comprises several events, of which some are not completely understood. It has been shown that HSV-1 glycoproteins accumulate in the trans-Golgi network (TGN) and in TGN-derived vesicles. It is also accepted that HSV-1 acquires its final morphology through a secondary envelopment by budding into TGN-derived vesicles coated with viral glycoproteins and tegument proteins. Nevertheless, several aspects of this process remain elusive. The small GTPase Rab27a has been implicated in regulated exocytosis, and it seems to play a key role in certain membrane trafficking events. Rab27a also seems to be required for human cytomegalovirus assembly. However, despite the involvement of various Rab GTPases in HSV-1 envelopment, there is, to date, no data reported on the role of Rab27a in HSV-1 infection. RESULTS: Herein, we show that Rab27a colocalized with GHSV-UL46, a tegument-tagged green fluorescent protein-HSV-1, in the TGN. In fact, this small GTPase colocalized with viral glycoproteins gH and gD in that compartment. Functional analysis through Rab27a depletion showed a significant decrease in the number of infected cells and viral production in Rab27a-silenced cells. CONCLUSIONS: Altogether, our results indicate that Rab27a plays an important role in HSV-1 infection of oligodendrocytic cells.

Concepts: Cytomegalovirus, Encephalitis, HIV, Infection, Herpes simplex, Herpes simplex virus, Herpesviridae, Virus

169

Tick-borne encephalitis (TBE) is endemic to Europe and medically highly significant. This study, focused on Poland, investigated individual risk factors for TBE symptomatic infection.

Concepts: Social status, Socioeconomic status, Encephalitis, Case-control study, Disease, Infectious disease, Europe, Epidemiology

167

BACKGROUND: The genus Flavivirus includes several pathogenic agents that cause severe illness in humans. Re-emergence of West Nile virus in Europe and continuous spread of certain flaviviruses such as dengue, yellow fever and Japanese encephalitis viruses represent a global danger to public health. Therefore, a rapid and accurate molecular method is required for diagnostics and epidemiological surveillance of flaviviruses. METHODS: A Pan-Flavi quantitative RT-PCR assay using a Locked-Nucleic Acid probe targeting the flavivirus NS5 gene was developed and optimized to detect a wide range of flaviviruses simultaneously. The specificity and sensitivity of the Pan-Flavi assay were tested using RNA of different flaviviruses and non-flaviviruses. Furthermore, the assay was compared directly to flavivirus species-specific assays for the ability to detect flaviviruses sensitively. RESULTS: Two degenerate primers and one Locked-Nucleic Acids probe were designed to amplify most of the flaviviruses. To increase the specificity and fluorescence signal of the Pan-Flavi assay for detection of yellow fever virus and dengue virus 4, additional primers and probes were included. Viral RNA of thirty different flaviviruses was detected, verifying the broad range specificity. The testing of this assay was successful, using standard plasmid and RNA dilutions of yellow fever virus vaccine strain, dengue virus 1 and tick-borne encephalitis virus, with a sensitivity limit of 10–100 genome copies/reaction. Also comparatively good results were achieved for detecting different flaviviruses by the Pan-Flavi assay when compared to the flavivirus species-specific assays. CONCLUSION: The assay is rapid, broad-range flavivirus-specific and highly sensitive making it a valuable tool for rapid detection of flaviviruses in livestock samples, epidemiological studies or as useful complement to single flavivirus-specific assays for clinical diagnosis.

Concepts: Malaria, Encephalitis, Ribavirin, Viral diseases, Flavivirus, West Nile virus, Flaviviridae, Flaviviruses

165

Genital herpes is the manifestation of a herpes simplex virus 2 infection. Standard treatment uses both local and systemic approaches. Here, we report on the results of a local therapy approach with 31 female patients at a gynecological practice. In the here-described approach, established genital herpes infection was treated with the medical device Herpotherm(®), with or without virostatic drugs. Herpotherm(®) is a certified medical device operating on the basis of local heat application. Parameters evaluated during the approach were (i) subjective patient assessments and (ii) objective assessment of the physician. In the described therapy approach a positive effect in terms of nature and severity in the course of the disease using Herpotherm(®) could be demonstrated. It could be shown that Herpotherm(®) can also be used for genital herpes and that it is well tolerated. In relation to other therapies using topical treatment for genital herpes, an extremely rapid reduction of pain and herpetic symptoms could be observed. Intolerances or discontinued use as a result of complications were not observed.

Concepts: Disease, Assessment, Encephalitis, Herpes simplex virus, Medicine, Herpesviridae, Virus, Herpes simplex

163

Japanese encephalitis virus (JEV) causes acute central nervous system (CNS) disease in humans, in whom the clinical symptoms vary from febrile illness to meningitis and encephalitis. However, the mechanism of severe encephalitis has not been fully elucidated. In this study, using a mouse model, we investigated the pathogenetic mechanisms that correlate with fatal JEV infection. Following extraneural infection with the JaOArS982 strain of JEV, infected mice exhibited clinical signs ranging from mild to fatal outcome. Comparison of the pathogenetic response between severe and mild cases of JaOArS982-infected mice revealed increased levels of TNF-α in the brains of severe cases. However, unexpectedly, the mortality rate of TNF-α KO mice was significantly increased compared with that of WT mice, indicating that TNF-α plays a protective role against fatal infection. Interestingly, there were no significant differences of viral load in the CNS between WT and TNF-α KO mice. However, exaggerated inflammatory responses were observed in the CNS of TNF-α KO mice. Although these observations were also obtained in IL-10 KO mice, the mortality and enhanced inflammatory responses were more pronounced in TNF-α KO mice. Our findings therefore provide the first evidence that TNF-α has an immunoregulatory effect on pro-inflammatory cytokines in the CNS during JEV infection and consequently protects the animals from fatal disease. Thus, we propose that the increased level of TNF-α in severe cases was the result of severe disease, and secondly that immunopathological effects contribute to severe neuronal degeneration resulting in fatal disease. In future, further elucidation of the immunoregulatory mechanism of TNF-α will be an important priority to enable the development of effective treatment strategies for Japanese encephalitis.

Concepts: Encephalitis, Mouse, Symptom, Inflammation, Infection, Brain, Central nervous system, Nervous system

125

Herpes simplex virus 2 (HSV2) is a human herpesvirus found worldwide that causes genital lesions and more rarely causes encephalitis. This pathogen is most common in Africa, and particularly in central and east Africa, an area of particular significance for the evolution of modern humans. Unlike HSV1, HSV2 has not simply co-speciated with humans from their last common ancestor with primates. HSV2 jumped the species barrier between 1.4 and 3 MYA, most likely through intermediate but unknown hominin species. In this article, we use probability-based network analysis to determine the most probable transmission path between intermediate hosts of HSV2, from the ancestors of chimpanzees to the ancestors of modern humans, using paleo-environmental data on the distribution of African tropical rainforest over the last 3 million years and data on the age and distribution of fossil species of hominin present in Africa between 1.4 and 3 MYA. Our model identifies Paranthropus boisei as the most likely intermediate host of HSV2, while Homo habilis may also have played a role in the initial transmission of HSV2 from the ancestors of chimpanzees to P.boisei.

Concepts: Encephalitis, Evolution, Herpes simplex, Africa, Virus, Herpesviridae, Herpes simplex virus, Human

28

ASP2151 (amenamevir) is a helicase-primase complex inhibitor with antiviral activity against herpes simplex virus (HSV)-1, HSV-2, and varicella-zoster virus (VZV). To assess combination therapy of ASP2151 with existing antiherpes agents against HSV-1, HSV-2, and VZV, we conducted in vitro and in vivo studies of two-drug combinations. The combination activity effect of ASP2151 with nucleoside analogs acyclovir (ACV), penciclovir (PCV), or vidarabine (VDB) was tested via plaque-reduction assay and MTS assay, and the data were analyzed using isobolograms and response surface modeling. In vivo combination therapy of ASP2151 with valaciclovir (VACV) was studied in an HSV-1-infected zosteriform spread mouse model. The antiviral activity of ASP2151 combined with ACV and PCV against ACV-susceptible HSV-1, HSV-2, and VZV showed a statistically significant synergistic effect (P<0.05). ASP2151 with VDB was observed to have additive effects against ACV-susceptible HSV-2 and synergistic effects against VZV. In the mouse model of zosteriform spread, the inhibition of disease progression via combination therapy was more potent than that of either drugs as monotherapy (P<0.05). These results indicate that the combination therapies of ASP2151 with ACV and PCV have synergistic antiherpes effects against HSV and VZV infections and may be feasible in case of severe disease, such as herpes encephalitis or in patients with immunosuppression.

Concepts: Alphaherpesvirinae, Herpes zoster, Virus latency, Herpes simplex, Herpes simplex virus, Virus, Herpesviridae, Encephalitis

28

BACKGROUND: Development of more effective therapies for genital herpes simplex type 2 (HSV-2) infections remains a priority. The Toll-like receptors (TLR) are attractive targets for the immunomodulation of primary and recurrent genital herpes infection. The guinea pig model of genital HSV-2 disease was therefore used to evaluate the efficacy of a new TLR7 agonist, SMIP-7.7 METHODS: The effects of SMIP-7.7 at concentrations between 0.90 and 0.09% were compared to the vehicle control or Aldara® as treatment for genital HSV-2 infections. Following intravaginal inoculation of Hartley guinea pigs with 10(6) pfu HSV-2 (MS strain), animals were treated intravaginally beginning at 36 hours post infection. Animals were evaluated for acute disease, acute virus replication, recurrent disease and shedding as well as infection of the dorsal root ganglia. RESULTS: Treatment with SMIP-7.7 significantly decreased mean total lesion scores during primary infection (all doses, P < 0.01, compared to vehicle control and similar to Aldara®). Vaginal virus titers were reduced in treated animals compared to vehicle control (P <0.001 for each treatment vs. vehicle control on day 4). Treatment with SMIP-7.7 also significantly decreased the number of recurrent lesion days, the number of days with recurrent virus shedding and decreased the infection of the dorsal root ganglia compared to the vehicle control and similar to Aldara®. As opposed to Aldara®, SMIP-7.7 did not induce fever or weight loss during treatment. CONCLUSIONS: SMIP-7.7 improves the outcome of primary and recurrent HSV-2 disease comparable to Aldara® but without some of the side effects associated with Aldara®.

Concepts: Encephalitis, Toll-like receptor, Herpes simplex virus, Immune system, Viral shedding, Herpesviridae, Herpes simplex, Virus

27

Japanese encephalitis virus (JEV), a main cause of severe viral encephalitis in humans, has a complex ecology, composed of a cycle involving primarily waterbirds and mosquitoes, as well as a cycle involving pigs as amplifying hosts. To date, JEV transmission has been exclusively described as being mosquito-mediated. Here we demonstrate that JEV can be transmitted between pigs in the absence of arthropod vectors. Pigs shed virus in oronasal secretions and are highly susceptible to oronasal infection. Clinical symptoms, virus tropism and central nervous system histological lesions are similar in pigs infected through needle, contact or oronasal inoculation. In all cases, a particularly important site of replication are the tonsils, in which JEV is found to persist for at least 25 days despite the presence of high levels of neutralizing antibodies. Our findings could have a major impact on the ecology of JEV in temperate regions with short mosquito seasons.

Concepts: Immune system, Infection, West Nile virus, Insect, Brain, Central nervous system, Encephalitis, Nervous system