Full-length infectious clone of a low passage dengue virus serotype 2 from Brazil

Full-length dengue virus (DENV) cDNA clones are an invaluable tool for many studies, including those on the development of attenuated or chimeric vaccines and on host-virus interactions. Furthermore, the importance of low passage DENV infectious clones should be highlighted, as these may harbour critical and unique strain-specific viral components from field-circulating isolates. The successful construction of a functional Brazilian low passage DENV serotype 2 full-length clone through homologous recombination reported here supports the use of a strategy that has been shown to be highly useful by our group for the development of flavivirus infectious clones and replicons.     

Genetic portrait of Lisboa immigrant population from Cabo Verde with mitochondrial DNA analysis

Journal of Genetics -     

‘Ins’ and ‘outs’ of triple therapy

Chronic oral anticoagulant treatment is obligatory in patients (class I) with mechanical heart valves and in patients with atrial fibrillation with CHADS2 score >1. When these patients undergo percutaneous coronary intervention with placement of a stent, there is also an indication for treatment with aspirin and clopidogrel. Unfortunately, triple therapy is known to increase the bleeding risk. For this group of patients, the bottom line is to find the ideal therapy in patients with indications for both chronic anticoagulation therapy and percutaneous intervention to prevent thromboembolic complications such as stent thrombosis without increasing the risk of bleeding. (Neth Heart J 2010;18:444-50.)     

Nonreductive release of O-linked oligosaccharides from mucin glycoproteins for structure/function assignments as neoglycolipids: application in the detection of novel ligands for E-selectin

The neoglycolipid technology comprises several microproceduresinvolving the generation of lipid-linked oligosaccharide probesfor carbohydrate recognition studies in conjunction with oligosaccharidesequence determination by mass spectrometry. Although applicableto any desired oilgosaccharides, procedures are greatly facilitatedif the ohgosaccharides are nonreduced, as conjugation is byreductive amination of a reducing end aldehyde to a phosphatidylethanolamine.Using bovine submaxillary mucin as a model for release of O-glycansin the reducing state, and based on yields of neoglycolipidsand side-products from "peeling" reactions and degradation,aqueous ethylamine 70% w/v at 22°C for 48 h has been selectedin preference to other conditions, triethylainine, sodium hydroxide,and bydrazine. The integrity of the main acidic and neutraloligosaccharides released under these conditions, di- to octasaccharides,was established by analyses of free oligosaccharides by liquidsecondary ion mass spectrometry (LSIMS) and of the derived neoglycolipidsby TLCLSIMS; the repertoire compared favorably with that ofthe oligosaccharide alditols generated by conventional reductivealkaline borohydride treatment. More forcing conditions of ethylamine70% w/v at 65°C for 6 h were required to release oligosaccharidesfrom porcine gastric mucin; di- to nonasaccharides were obtainedof which about one-third had an intact core GalNAc. Relativeto yields after reductive alkaline hydrolysis, the overall yieldsfor these two glycoproteins were 20% and 40–50% for acidicand neutral oligosaccharides, respectively. Among O-glycansreleased from an ovarian cystadenoma glycoprotein using ethylamine,three variants of the sulfated Le^a/x sequences were identifiedas ligands for the endothelial adhesion molecule E-selectin,one of which is based on the unusual backbone Gal-3/4GlcNAc-3Gal-3Gal. mucins O-linked oligosaccharides TLC-LSIMS neoglycolipids E-selectin     

The human immunodeficiency virus type 1 nef gene can to a large extent replace simian immunodeficiency virus nef in vivo.

The nef gene of the pathogenic simian immunodeficiency virus (SIV) 239 clone was replaced with primary human immunodeficiency virus type 1 (HIV-1) nef alleles to investigate whether HIV-1 Nef can substitute for SIV Nef in vivo. Initially, two rhesus macaques were infected with the chimeric viruses (Nef-SHIVs). Most of the nef alleles obtained from both animals predicted intact open reading frames. Furthermore, forms containing upstream nucleotide substitutions that enhanced expression of the inserted gene became predominant. One animal maintained high viral loads and slowly progressed to immunodeficiency. nef long terminal repeat sequences amplified from this animal were used to generate a second generation of Nef-SHIVs. Two macaques, which were subsequently infected with a mixture of cloned chimeric viruses, showed high viral loads and progressed to fatal immunodeficiency. Five macaques received a single molecular clone, named SHIV-40K6. The SHIV-40K6 nef allele was active in CD4 and class I major histocompatibility complex downregulation and enhanced viral infectivity and replication. Notably, all of the macaques inoculated with SHIV-40K6 showed high levels of viral replication early in infection. During later stages, however, the course of infection was variable. Three animals maintained high viral loads and developed immunodeficiency. Of the remaining two macaques, which showed decreasing viral loads after the acute phase of infection, only one efficiently controlled viral replication and remained asymptomatic during 1.5 years of follow-up. The other animal showed an increasing viral load and developed signs of progressive infection during later stages. Our data demonstrate that HIV-1 nef can, to a large extent, functionally replace SIVmac nef in vivo.     

Microsphere embolisation as an alternative for alcohol in percutaneous transluminal septal myocardial ablation

Background

Percutaneous transluminal septal myocardial ablation using microsphere embolisation is a new interventional technique to treat patients with hypertrophic obstructive cardiomyopathy.

Methods and results

In two patients, considered at high risk for myectomy, targeted septal perforators were occluded with microsphere embolisation instead of alcohol ablation to reduce left ventricular outflow gradient. In both cases the left ventricular outflow tract gradient was immediately reduced. No adverse events occurred.

Conclusion

This is the first clinical experience with Embozene® Microspheres in the Netherlands as an alternative for alcohol septal ablation. In both cases it resulted in immediate improvement in the haemodynamics, without any adverse events.     

Importance of the N-distal AP-2 binding element in Nef for simian immunodeficiency virus replication and pathogenicity in rhesus macaques

Point mutations in SIVmac239 Nef disrupting CD4 downmodulation and enhancement of virion infectivity attenuate viral replication in acutely infected rhesus macaques, but changes selected later in infection fully restore Nef function (A. J. Iafrate et al., J. Virol. 74:9836-9844, 2000). To further evaluate the relevance of these Nef functions for viral persistence and disease progression, we analyzed an SIVmac239 Nef mutant containing a deletion of amino acids Q64 to N67 (delta64-67Nef). This mutation inactivates the N-distal AP-2 clathrin adaptor binding element and disrupts the abilities of Nef to downregulate CD4, CD28 and CXCR4 and to stimulate viral replication in vitro. However, it does not impair the downmodulation of CD3 and class I major histocompatibility complex (MHC-I) or MHC-II and the upregulation of the MHC-II-associated invariant chain, and it has only a moderate effect on the enhancement of virion infectivity. Replication of the delta64-67Nef variant in acutely infected macaques was intermediate between grossly nef-deleted and wild-type SIVmac239. Subsequently, three of six macaques developed moderate to high viral loads and developed disease, whereas the remaining animals efficiently controlled SIV replication and showed a more attenuated clinical course of infection. Sequence analysis revealed that the deletion in nef was not repaired in any of these animals. However, some changes that slightly enhanced the ability of Nef to downmodulate CD4 and moderately increased Nef-mediated enhancement of viral replication and infectivity in vitro were observed in macaques developing high viral loads. Our results imply that both the Nef functions that were disrupted by the delta64-67 mutation and the activities that remained intact contribute to viral pathogenicity.     

An inhibitor of O-glycosylation induces apoptosis in NIH3T3 cells and developing mouse embryonic mandibular tissues

The family of UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferases (ppGaNTases) is responsible for initiating mucin-type O-linked glycosylation in higher eukaryotes. To begin to examine the biological role of O-linked glycosylation, mammalian cells were treated with a small molecule inhibitor (designated 1-68A, Ref. 15) of ppGaNTase activity. NIH3T3 cells exposed to the inhibitor were shown to undergo a significant reduction in cell surface O-glycosylation as detected by staining with jacalin and peanut agglutinin lectins after 30 min of treatment; no reduction in staining using antibodies to O-linked N-acetylglucosamine or the lectin concanavalin A was detected. Apoptosis was also observed in treated cells after 45 min of exposure, ostensibly following the O-glycosylation reduction. Overexpression of several different ppGaNTase isoforms restored cell surface O-glycosylation and rescued inhibitor-induced apoptosis. Additionally, mouse embryonic mandibular organ cultures exposed to 1-68A developed abnormally, presumably because of epithelial and mesenchymal apoptosis that followed a reduction in jacalin and peanut agglutinin staining. Our studies suggest that mucin-type O-linked glycosylation may be required for normal development and that ppGaNTases may play a role in the regulation of apoptosis.