[Dengue shock syndrome: decoding the pathophysiology]. / Le syndrome de choc de dengue: vers un décryptage de la physiopathologie.

Considered as major human arbovirosis, dengue occurs in several clinical forms. Some forms can lead to fatal complications such as dengue shock syndrome. This hypovolemic shock cannot be predicted and specific curative treatments are still lacking, and thus management of patients with dengue is difficult. The purpose of this review is to describe state-of-the-art of the knowledge on the pathophysiology of shock syndrome and to highlight the interest of high-content screening methods in translational approaches between research and medicine for investigation of individual response during dengue shock syndrome.

High yield synthesis, purification and characterisation of the RNase L activators 5'-triphosphate 2'-5'-oligoadenylates.

Upon viral infection, double-stranded viral RNA is detected very early in the host cell by several cellular 2'-5' oligoadenylate synthetases, which synthesize 2'-5' adenylate oligonucleotides that activate the cellular RNase L, firing an early primary antiviral response through self and non-self RNA cleavage. Transfecting cells with synthetic 2'-5' adenylate oligonucleotides activate RNase L, and thus provide a useful shortcut to study the early steps of cellular and viral commitments into this pathway. Defined 2'-5' adenylate oligonucleotides can be produced in vitro, but their controlled synthesis, purification, and characterisation have not been reported in detail. Here, we report a method suitable to produce large amounts of 2-5As of defined lengths in vitro using porcine OAS1 (pOAS) and human OAS2 (hOAS). We have synthesized a broad spectrum of 2-5As at the milligram scale and report an HPLC-purification and characterisation protocol with quantified yield for 2-5A of various lengths.

Phylogeny of the genus flavivirus using complete coding sequences of arthropod-borne viruses and viruses with no known vector.

Attempts to define the evolutionary relationships and origins of viruses in the genus Flavivirus are hampered by the lack of genetic information particularly amongst the non-vectored flaviviruses. Using a novel protocol for sequence determination, the first complete coding sequence of St Louis encephalitis virus and those of two representative non-vectored flaviviruses, Rio Bravo (isolated from bat) and Apoi (isolated from rodent), are reported. The encoded polyproteins of Rio Bravo and Apoi virus are the smallest described to date within the genus FLAVIVIRUS: The highest similarities with other flaviviruses were found in the NS3 and NS5 genes. The proteolytic cleavage sites for the viral serine protease were highly conserved among the flaviviruses completely sequenced to date. Comparative genetic amino acid alignments revealed that p-distance cut-off values of 0.330-0.470 distinguished the arthropod-borne viruses according to their recognized serogroups and Rio Bravo and Apoi virus were assigned to two distinct non-vectored virus groups. Within these serogroups, cladogenesis based on the complete ORF sequence was similar to trees based on envelope and NS5 sequences. In contrast, branching patterns at the deeper nodes of the tree were different from those reported in the previous study of NS5 sequences. The significance of these observations is discussed.

[Imported dengue hemorrhagic fever: aprops of 1 case presenting with signs of acute alithiasic cholecystitis]. / Dengue hémorragique d'importation: à propos d'un cas ayant présenté des signes de cholécystite aiguë alithiasique.

Dengue is prevalent in all subtropical areas. Hemorrhagic forms of the disease were first described in southeast Asia but have now been observed on several continents. Travelers are at risk for infection and the likelihood of imported dengue has grown in relation to volume of air traffic. In developed countries, dengue usually presents in the benign form, but sudden aggravation is always possible. The purpose of this report is to describe a case of imported dengue hemorrhagic fever associated with abdominal pain in a traveler returning from Asia. Radiological findings were suggestive of nonlithiasic cholecystitis. Similar ultrasound feature have been reported by pediatric groups during dengue outbreaks in Asia. Previous findings have shown that bladder involvement is a predictive sign of severe disease and impending shock. Surgery is contraindicated in these patients. Close clinical and laboratory surveillance is necessary due to the high risk of aggravation. The pathogenesis of this severe life-threatening form of the disease is unclear. A possible explanation is involvement of a more virulent strain of virus. Dengue should always be considered after malaria in the differential diagnosis of returning travelers patients presenting fever.

Characterisation of the binding sites of monoclonal antibodies reacting with the Plasmodium falciparum rhoptry protein RhopH3.

Twenty one mouse monoclonal antibodies reacting or cross-reacting with the Plasmodium falciparum RhopH3 protein reacted with Ag44, a recombinant antigen expressing the 134 C-terminal RhopH3 residues. Using overlapping peptides scanning this region, two major binding sites were identified. The first one, recognised by eight anti-RhopH3 and seven cross-reacting mAbs, was mapped to the sequence Thr Asp Asn Thr Tyr or Thr Asp Asn Thr Tyr Lys (aa 823-828), depending on the support used for synthesis. Binding specificity and affinity were investigated for a subset of four mAbs reacting with this epitope, including one growth inhibitory mAb. Systematic replacements showed that the various mAbs had similar requirements. The inhibitory mAb presented a higher affinity for this sequence and bound to the adjacent sequence, Tyr Lys Glu Met Glu Leu (aa 827-832). A 2nd binding site, located around residue 850, was recognised by two anti-RhopH3 mAbs, which reacted exclusively with the 110 kDa RhopH3 polypeptide, unlike the other mAbs, which reacted with the 110 and 105 kDa RhopH3 antigens. This suggested that the 105 kDa RhopH3 polypeptide derives from the 110 kDa by C-terminal processing. Experimental evidence substantiating this conclusion was provided by the observation that antisera raised to peptides located upstream of the putative cleavage site reacted with both the 110 kDa and 105 kDa polypeptides, whereas antisera raised to the 45 C-terminal amino acids of RhopH3 reacted exclusively with the larger, 110 kDa product. The biological significance of this processing is discussed.

Serum iron, glutamic oxalacetic transaminase and creatine phosphokinase in acute myocardial infarction. A comparative study.

The serum iron was subnormal on the first three days, following acute myocardial infarction in thirty patients. This is significantly less than the incidence of abnormalities demonstrated by assays of creatine phosphokinase (CPK) and glutamic oxalacetic transaminase (SGOT) in serum. Occasional patients had abnormal serum iron concentrations in association with normal CPK activities. For this reason serum iron determination may usefully supplement CPK activity measurements and possibly those of SGOT activity as an aid to the detection of acute myocardial infarction.