Class II ADP-ribosylation factors are required for efficient secretion of Dengue viruses

This article is available open access through the publisher’s website.Identification and characterization of virus-host interactions are very important steps toward a better understanding of the molecular mechanisms responsible for disease progression and pathogenesis. To date, very few cellular factors involved in the life cycle of flaviviruses, which are important human pathogens, have been described. In this study, we demonstrate a crucial role for class II Arf proteins (Arf4 and Arf5) in the dengue flavivirus life cycle. We show that simultaneous depletion of Arf4 and Arf5 blocks recombinant subviral particle secretion for all four dengue serotypes. Immunostaining analysis suggests that class II Arf proteins are required at an early pre-Golgi step for dengue virus secretion. Using a horseradish peroxidase protein fused to a signal peptide, we show that class II Arfs act specifically on dengue virus secretion without altering the secretion of proteins through the constitutive secretory pathway. Co-immunoprecipitation data demonstrate that the dengue prM glycoprotein interacts with class II Arf proteins but not through its C-terminal VXPX motif. Finally, experiments performed with replication-competent dengue and yellow fever viruses demonstrate that the depletion of class II Arfs inhibits virus secretion, thus confirming their implication in the virus life cycle, although data obtained with West Nile virus pointed out the differences in virus-host interactions among flaviviruses. Our findings shed new light on a molecular mechanism used by dengue viruses during the late stages of the life cycle and demonstrate a novel function for class II Arf proteins.Research Fund for Control of Infectious Diseases of Hong Kong and BNP Paribas Corporate and Investment Banking

Comparative susceptibility of mosquito populations in North Queensland, Australia to oral infection with dengue virus.

Dengue is the most prevalent arthropod-borne virus, with at least 40% of the world's population at risk of infection each year. In Australia, dengue is not endemic, but viremic travelers trigger outbreaks involving hundreds of cases. We compared the susceptibility of Aedes aegypti mosquitoes from two geographically isolated populations to two strains of dengue virus serotype 2. We found, interestingly, that mosquitoes from a city with no history of dengue were more susceptible to virus than mosquitoes from an outbreak-prone region, particularly with respect to one dengue strain. These findings suggest recent evolution of population-based differences in vector competence or different historical origins. Future genomic comparisons of these populations could reveal the genetic basis of vector competence and the relative role of selection and stochastic processes in shaping their differences. Lastly, we show the novel finding of a correlation between midgut dengue titer and titer in tissues colonized after dissemination

HUBUNGAN STATUS GIZI DENGAN DERAJAT INFEKSI VIRUS DENGUE PADA ANAK

ABSTRAKInfeksi virus dengue merupakan infeksi yang disebabkan oleh virus dengue. Indonesia merupakan negara hiperendemik untuk infeksi virus dengue. Infeksi virus dengue banyak menyerang anak dan erat kaitannya dengan sistem imun. Status gizi sangat berperan penting terhadap respon imun anak. Keadaan imunitas anak dapat mempengaruhi derajat klinis infeksi virus dengue yang dideritanya. Penelitian ini bertujuan untuk menganalisis hubungan antara status gizi dengan derajat infeksi virus dengue pada anak. Penelitian ini merupakan penelitian survei analitik dengan rancangan retrospective. Penelitian ini menggunakan data rekam medik pasien infeksi virus dengue tahun 2013- 2015 dengan jumlah responden 55 orang. Hasil analisis korelatif dengan uji Spearman menunjukkan adanya hubungan antara status gizi dengan infeksi virus dengue (p= 0,007, r = 0,358, OR=20,5). Dapat disimpulkan bahwa terdapat hubungan antara status gizi dengan derajat infeksi virus dengue dimana anak dengan gizi kurang dan gizi normal cenderung menderita infeksi virus dengue yang lebih ringan (demam dengue, DBD derajat I dan DBD derajat II) sedangkan anak dengan gizi lebih dan obesitas berpeluang 20,5 kali untuk menderita DBD berat (DBD derajat III dan derajat IV).Kata Kunci : infeksi virus dengue,status gizi, anak ABSTRACTInfection of dengue virus is an infection caused by the dengue virus. Indonesia is a hyper-endemic country in term of dengue virus infection. Such infection is common in children and is closely related to the immune system. Nutritional status is very important to the immune response of the children. Their immune conditions may influence the degree of clinical infection they suffer. This research aimed to analyze the relationship between the nutritional status and the degree of dengue virus infection in children. This research is an analytic survey with a retrospective design. It used the medical records of 55 patients infected with dengue virus between 2013 and 2015. The results of correlative analysis using the Spearman test showed that there was a relationship between the nutritional status and the dengue virus infection (p = 0.007, r = 0.358, OR = 20.5). It is concluded that there was a relationship between nutritional status and degree of dengue virus infection ,children with malnutrition and normal nutritional indicate infection with dengue virus a milder (dengue fever, DHF grade I and DHF grade II) meanwhile children with overweight and obesity is chance 20,5 times to suffer severe dengue (DHF stage III and stage IV).Keywords: dengue infection, nutritional status, childre

Immunogenicity of NS4b dengue 3 virus mimotope presented to the immune system as multiple antigen peptide system

The availability of random peptide libraries displayed on bacteriophage (RPL) has provided a powerful tool for selecting sequences that mimic binding properties of natural antigen epitopes (mimotopes). These mimotopes can be used for vaccine design, drug development, and diagnostic assays. Several mimotopes have been shown to induce production of antibodies against the natural antigen. We have previously identified four dengue virus mimotopes from a phage-displayed peptide library using antidengue 3 human sera. Three of them showed similarity in their amino acid sequences with the NS4b proteins of dengue. Few studies have examined the role of NS4b proteins in the antibody response to dengue virus infection. A multiple antigen peptide (MAP) system was chemically synthesized containing this mimotope (NS4b MAP), and BALB/c mice were immunized to evaluate its immunogenicity. Antipeptide responses were induced and recognised DENV-3 infected cells as determined by immunofluorescence. The high levels of the IgG2a subtype against NS4bMAP suggest the induction of a Th1-like response. Our findings suggest that the NS4b mimotope might be a useful tool for the development of multiepitope diagnostic assays, dengue virus vaccine design, and pathogenesis studies

Intrahost Selection Pressures Drive Rapid Dengue Virus Microevolution in Acute Human Infections.

Dengue, caused by four dengue virus serotypes (DENV-1 to DENV-4), is a highly prevalent mosquito-borne viral disease in humans. Yet, selection pressures driving DENV microevolution within human hosts (intrahost) remain unknown. We employed a whole-genome segmented amplification approach coupled with deep sequencing to profile DENV-3 intrahost diversity in peripheral blood mononuclear cell (PBMC) and plasma samples from 77 dengue patients. DENV-3 intrahost diversity appears to be driven by immune pressures as well as replicative success in PBMCs and potentially other replication sites. Hotspots for intrahost variation were detected in 59%-78% of patients in the viral Envelope and pre-Membrane/Membrane proteins, which together form the virion surface. Dominant variants at the hotspots arose via convergent microevolution, appear to be immune-escape variants, and were evolutionarily constrained at the macro level due to viral replication defects. Dengue is thus an example of an acute infection in which selection pressures within infected individuals drive rapid intrahost virus microevolution

Chimeric Yellow Fever/Dengue Virus as a Candidate Dengue Vaccine: Quantitation of the Dengue Virus-Specific CD8 T-Cell Response

We have constructed a chimeric yellow fever/dengue (YF/DEN) virus, which expresses the premembrane (prM) and envelope (E) genes from DEN type 2 (DEN-2) virus in a YF virus (YFV-17D) genetic background. Immunization of BALB/c mice with this chimeric virus induced a CD8 T-cell response specific for the DEN-2 virus prM and E proteins. This response protected YF/DEN virus-immunized mice against lethal dengue encephalitis. Control mice immunized with the parental YFV-17D were not protected against DEN-2 virus challenge, indicating that protection was mediated by the DEN-2 virus prM- and E-specific immune responses. YF/DEN vaccine-primed CD8 T cells expanded and were efficiently recruited into the central nervous systems of DEN-2 virus challenged mice. At 5 days after challenge, 3 to 4% of CD8 T cells in the spleen were specific for the prM and E proteins, and 34% of CD8 T cells in the central nervous system recognized these proteins. Depletion of either CD4 or CD8 T cells, or both, strongly reduced the protective efficacy of the YF/DEN virus, stressing the key role of the antiviral T-cell response