RESUMEN
Myristoylated 21- and 25-residue N-terminal peptides of the Nef protein of HIV-1 lysed human erythrocytes and were cytotoxic toward a human CD4+ T cell line, CEM, and primary human peripheral blood mononuclear cells (PBMCs). The corresponding nonmyristoylated N-terminal peptides were only very weakly hemolytic and cytotoxic. A myristoylated peptide consisting of residues 31-50 of Nef was neither hemolytic nor cytotoxic. Alteration of the tryptophan residue at position 13 to a serine did not change the hemolytic and cytotoxic activity. Studies of the ultraviolet fluorescence of the tryptophan at position 5 in the peptide, using an artificial membrane system and fluorescence-quenching agents that inserted into the bilayer at different levels, suggested that myristoylation results in this residue being brought into contact with the upper hydrocarbon region of the lipid bilayer of the cell membrane. This tryptophan is flanked by a number of polar residues that would maintain it in this position, resulting in a considerable increase in disorder in the upper regions of the lipid bilayer, leading to its destabilization and to lysis. The cytotoxic activity of the myristoylated Nef fragments may, in part, explain the killing and deletion of cells, especially in lymphoid tissues, during HIV infection.
Asunto(s)
Citotoxicidad Inmunológica/efectos de los fármacos , Productos del Gen nef/farmacología , VIH-1 , Oligopéptidos/farmacología , Secuencia de Aminoácidos , Línea Celular/efectos de los fármacos , Pruebas Inmunológicas de Citotoxicidad , VIH-1/química , Hemólisis/efectos de los fármacos , Humanos , Membrana Dobles de Lípidos/química , Liposomas , Datos de Secuencia Molecular , Ácidos Mirísticos/metabolismo , Oligopéptidos/síntesis química , Espectrometría de Fluorescencia , Productos del Gen nef del Virus de la Inmunodeficiencia HumanaRESUMEN
Vpr is a virion-associated protein of human immunodeficiency virus type 1 (HIV-1) whose function in acquired immune deficiency syndrome (AIDS) has been uncertain. We previously employed yeast as a model to examine the effects of Vpr on basic cellular functions; intracellular Vpr was shown to cause cell-growth arrest and structural defects, and these effects were caused by a region of Vpr containing the sequence HFRIGCRHSRIG. Here we show that peptides containing the H(S/F)RIG amino acid sequence motif cause death when added externally to a variety of yeast including Saccharomyces cerevisiae, Kluyveromyces lactis, Candida glabrata, Candida albicans and Schizosaccharomyces pombe. Such peptides rapidly entered the cell from the time of addition, resulting in cell death. Elevated levels of ions, particularly magnesium and calcium ions, abrogated the cytotoxic effect by preventing the Vpr peptides from entering the cells. Extracellular Vpr found in the serum, or breakdown products of extracellular Vpr, may have similar effects to the Vpr peptides described here and could explain the death of uninfected bystander cells during AIDS.
Asunto(s)
Productos del Gen vpr/genética , VIH-1/genética , Secuencia de Aminoácidos , División Celular/efectos de los fármacos , Permeabilidad de la Membrana Celular/efectos de los fármacos , Productos del Gen vpr/fisiología , VIH-1/patogenicidad , VIH-1/fisiología , Humanos , Concentración de Iones de Hidrógeno , Datos de Secuencia Molecular , Fragmentos de Péptidos/genética , Fragmentos de Péptidos/farmacología , Levaduras/citología , Levaduras/efectos de los fármacos , Levaduras/metabolismo , Productos del Gen vpr del Virus de la Inmunodeficiencia HumanaRESUMEN
Attempts to isolate viruses from 178,181 unengorged female mosquitoes collected from different ecologic areas of Sri Lanka yielded 31 isolates: 17 of Japanese encephalitis (JE) virus, nine of Getah virus, three of a Batai-related bunyavirus, and two of Arkonam virus. Culex tritaeniorhynchus and Mansonia uniformis mosquitoes were found to carry JE virus in a dry zone nonepidemic area, and Cx. pseudovishnui was found to carry it in a wet zone nonepidemic area. Japanese encephalitis virus was isolated from Cx. tritaeniorhynchus, Cx. gelidus, Cx. fuscocephala, and Cx. whitmorei during a human epidemic in the dry zone. Getah virus was isolated from Cx. tritaeniorhynchus, Cx. gelidus, and Cx. fuscocephala collected in the vicinity of swine. Isolations of Getah, Arkonam, and Batai-related viruses from Sri Lanka are reported for the first time.
Asunto(s)
Alphavirus/aislamiento & purificación , Culicidae/microbiología , Virus de la Encefalitis Japonesa (Especie)/aislamiento & purificación , Insectos Vectores/microbiología , Animales , Animales Lactantes , Culex/microbiología , Femenino , Técnica del Anticuerpo Fluorescente , Ratones , Orbivirus/aislamiento & purificación , Orthobunyavirus/aislamiento & purificación , Sri LankaRESUMEN
The ecology of Japanese encephalitis (JE) in different agro-climatological areas of Sri Lanka was studied in relation to the abundance of mosquito vectors, infection in domestic livestock, and human infection and disease. There was an inverse correlation between altitude and the abundance of potential JE vectors, as well as JE seroprevalence in domestic livestock and in man. Little or no JE infection was documented above 1200 m elevation. JE seroprevalences in cattle and goats were better predictors of human infection risk than was porcine seroprevalence. In areas with asynchronous porcine infection occurring over many months, high overall JE seroprevalence in pigs was found with little evidence of human infection. Porcine JE infection occurring in synchronous bursts associated with monsoonalrains was correlated with significant bovine, ovine and human seroprevalence in 2 low elevation study areas, Anuradhapura (dry zone) and Ragama (wet zone), with epidemic human JE in the former area and endemic disease in the latter.
Asunto(s)
Encefalitis Japonesa/epidemiología , Adolescente , Altitud , Animales , Animales Domésticos/inmunología , Anticuerpos Antivirales/análisis , Bovinos , Niño , Clima , Culicidae , Perros , Virus de la Encefalitis Japonesa (Especie)/inmunología , Encefalitis Japonesa/veterinaria , Femenino , Humanos , Insectos Vectores , Masculino , Prevalencia , Conejos , Población Rural , Estaciones del Año , Sri Lanka/epidemiología , Porcinos , Enfermedades de los Porcinos/epidemiologíaRESUMEN
A seroepidemiologic study of California (CAL) serogroup viruses (genus bunyavirus, family Bunyaviridae) was carried out on 952 human and 1,834 animal sera collected from different ecological zones of Sri Lanka (latitudes 5-10 degrees N, longitudes 79-82 degrees E). The sera were screened for neutralizing antibody to Lumbo (LUM), snowshoe hare (SSH), and trivittatus (TVT) viruses by plaque neutralization tests on Vero cells. Of 2,786 sera screened, 262 (9.5%) had antibody to one or more viruses Twenty-two sera, selected to represent different species of origin and reaction profiles, were titrated against nine CAL viruses: LUM, SSH, TVT, Tahyna (TAH), California encephalitis (CE), La Crosse (LAC), Inkoo (INK), Melao (MEL), and Guaroa (GRO). Results suggested that there were multiple CAL viruses active in Sri Lanka, one or more of them closely related to LUMBO and SSH viruses, and another related to MELAO virus. These viruses were active in both the wet and dry zones of the country, and infected humans as well as a range of domestic livestock.