Japanese encephalitis is frequent in Asia, with a severe prognosis, but rare in travelers.
Culex
mosquitoes transmit Japanese encephalitis virus. Risk factors are destination, duration of stay, ...summer and fall seasons, outdoor activities, and type of accommodation. We report the case of a French traveler to Nepal with neutralization-based serological confirmed Japanese encephalitis. He presented classical clinical (viral syndrome before an encephalitis status with behavioral disorder, global hypotonia, mutism, movement disorders, seizure, and coma), radiological (lesions of thalami, cortico-spinal tracts, and brainstem) and biological features (lymphocytic meningitis). Nowadays, the presence of Japanese encephalitis virus in Nepal, including mountain areas, is established but Japanese encephalitis remains rare in travelers returning from this area and neurologist physicians need to become familiar with this. We recommend vaccination for travelers spending a long period of time in Nepal and having at-risk outdoor activities.
The chikungunya virus (CHIKV) has become a substantial global health threat due to its massive re-emergence, the considerable disease burden and the lack of vaccines or therapeutics. We discovered a ...novel class of small molecules (1,2,3triazolo4,5-dpyrimidin-7(6H)-ones) with potent in vitro activity against CHIKV isolates from different geographical regions. Drug-resistant variants were selected and these carried a P34S substitution in non-structural protein 1 (nsP1), the main enzyme involved in alphavirus RNA capping. Biochemical assays using nsP1 of the related Venezuelan equine encephalitis virus revealed that the compounds specifically inhibit the guanylylation of nsP1. This is, to the best of our knowledge, the first report demonstrating that the alphavirus capping machinery is an excellent antiviral drug target. Considering the lack of options to treat CHIKV infections, this series of compounds with their unique (alphavirus-specific) target offers promise for the development of therapy for CHIKV infections.
The virion-associated dUTPase activities of caprine arthritis-encephalitis virus (CAEV) and visna virus were determined by using an assay which measures the actual ability of the dUTPase to prevent ...the dUTP misincorporations into cDNA during reverse transcription. We showed that the CAEV molecular clone from the Cork isolate was dUTPase-defective as a result of a single amino acid substitution. Using this point mutant and deletion mutants of CAEV as well as a deletion mutant of visna virus, we demonstrated that dUTPase-deficient viruses replicate similarly to wild-type viruses in dividing cells but show delayed replication in nondividing primary macrophages
The biological form of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) is a heterodimer consisting of two polypeptides, p66 and p51, which have identical N-termini. The p51 ...polypeptide is generated by action of viral protease cleaving the p66 polypeptide between residues Phe440 and Tyr441. Dimerization has been mostly studied using bacterially purified RT bearing amino acid changes in either subunit, but not in the context of HIV-1 particles. We introduced changes of conserved amino acid residues 430–438 into the protease-sensitive subdomain of the p66 subunit and analyzed the reverse transcriptase processing and function using purified variants and their corresponding HIV-1 recombinant clones. Our mutational analysis shows that the conserved Glu438 residue is critical for proper heterodimerization and function of virion-associated RT, but not of bacterially expressed RT. In contrast, the conserved Glu430, Glu432, and Pro433 residues are not important for dimerization of virion-associated RT. The network of interactions made by the Glu438 carboxyl group with neighboring residues is critical to protect the Phe440–Tyr441 from cleavage in the context of the p66/p51 heterodimer and may explain why the p66/p51 is not processed further to p51/p51.
Visna-maedi virus induces in sheep an interstitial lung disease characterised by an accumulation of smooth muscle cells (SMC) or myomatosis. Infection by HIV-1 has been recently associated with ...disorders of the vessel-derived cells: primary pulmonary hypertension, coronary artery disease and smooth muscle tumors in humans. We hypothesized that besides their regular targets (i.e. macrophages and lymphocytes), lentiviruses could infect smooth muscle cells. Smooth muscle cell cultures derived from ovine aorta were infected with visna-maedi virus strain K1514. The cultured cells were smooth muscle cells as demonstrated by their antigenic expression of alpha-actin and vimentin. The lentiviral infection of the smooth muscle cells was demonstrated by a typical cytopathic effect (syncytia), the expression of virus specific antigens and the presence of genomic RNA detected by Northern blot analysis and RT PCR. The detection of a reverse transcriptase activity, the presence of viral RNA in supernatants of infected smooth muscle cells detected by RT PCR and their ability to infect ovine permissive fibroblasts demonstrated a productive infection. The ability of smooth muscle cells to be infected by lentiviruses may participate in the pathogenesis of the tissue damage associated with the lentiviruses such as myomatosis in sheep and vascular disease in humans.
During the early step of the lytic cycle, visna provirus is first transcribed into two small multispliced mRNAs of 1.6 and 1.2 kilobases which may encode factors regulating the replication of visna ...virus (R. Vigne, V. Barban, G. Querat, V. Mazarin, T. Gourdou, and N. Sauze, Virology 161:218-217, 1987). By cDNA cloning and nucleotide sequencing, we determined that the 1.2-kilobase mRNA is 1,174 nucleotides long without the 3'-polyadenylated tail and is composed of four exons, two of which originated from the 5' and 3' ends,respectively, of the env gene region. Two overlapping open reading frames are present in each of these two exons. They were translated in vitro and gave riseto three proteins, two of 19 and 17 kilodaltons, termed VEP1, and one of 16.5 kilodaltons, termed STM. Only the VEP1 proteins were recognized by a hyperimmune anti-visna virus serum of infected sheep. Transient-expression assays performed in eucaryotic cells demonstrated that the cDNA clone describedhere has a trans-acting effect on transcription of the visna virus genes
Uracilation of DNA represents a constant threat to the survival of many organisms including viruses. Uracil may appear in DNA either by cytosine deamination or by misincorporation of dUTP. The ...HIV-1-encoded Vif protein controls cytosine deamination by preventing the incorporation of host-derived APOBEC3G cytidine deaminase into viral particles. Here, we show that the host-derived uracil DNA glycosylase UNG2 enzyme, which is recruited into viral particles by the HIV-1-encoded integrase domain, is essential to the viral life cycle. We demonstrate that virion-associated UNG2 catalytic activity can be replaced by the packaging of heterologous dUTPase into virion, indicating that UNG2 acts to counteract dUTP misincorporation in the viral genome. Therefore, HIV-1 prevents incorporation of dUTP in viral cDNA by UNG2-mediated uracil excision followed by a dNTP-dependent, reverse transcriptase-mediated endonucleolytic cleavage and finally by strand-displacement polymerization. Our findings indicate that pharmacologic strategies aimed toward blocking UNG2 packaging should be explored as potential HIV/AIDS therapeutics.
Soon after infection of ovine cell cultures, visna virus expression is first indicated by the accumulation of two multi-spliced transcripts of 1.2 and 1.6 kb that at present we have renamed 1.4 and ...1.7 kb according to their exact length. The early 1.4-kb mRNA encodes for a protein which increases the level of transcripts directed from visna virus long terminal repeat (trans-activation). This trans-activating protein was previously called VEP1 and at present is renamed as the product of the rev gene according to significant amino acid sequence homologies between this protein and the rev gene products of simian immunodeficiency virus and human immunodeficiency virus type 2. In this study, the 1.7-kb mRNA was cloned, sequenced, and in vitro translated. It is 1491 nucleotides long, contains two short open reading frames, (orfs), tat (previously orf S) and rev which is the bipartite trans-acting gene specific for the early 1.4-kb mRNA. The tat gene of visna virus encodes for a protein of 11 kDa which in transient expression assays has a positive transacting effect on transcription as the rev gene product does.