RESUMEN
Direct expression of hepatitis B virus (HBV) surface antigen (HBsAg) gene under the control of the Escherichia coli tryptophan operon (trp) promoter has been achieved. Synthesis of HBsAg (both complete and lacking its N-terminal segment) as a part of hybrid proteins with the N-terminal portion coded by genes cat, kan or bla is controlled by the appropriate promoters, as well as by the trp promoter. The highest levels of expression, including those for direct synthesis of HBsAg, provide the accumulation of about 10(5) polypeptide molecules per bacterial cell.
Asunto(s)
Escherichia coli/genética , Genes Virales , Antígenos de Superficie de la Hepatitis B/genética , Clonación Molecular , Escherichia coli/crecimiento & desarrollo , Escherichia coli/inmunología , Regulación de la Expresión Génica , Antígenos de Superficie de la Hepatitis B/aislamiento & purificación , Operón , PlásmidosRESUMEN
Calves of two breeds--Brown Latvian and Black and White, were immunized against bovine leukemia virus with an immunogen produced from short-term cultured blood lymphocytes of BLV-positive Brown Latvian cows. The immunogen contained the viral proteins gp51 and p24 as well as some cellular proteins. As determined by bioassay in sheep, it did not contain infective bovine leukemia virus. The calves were challenged by BLV-producing lymphocytes 2 weeks after the immunization procedure. Effective protection against BLV infection was induced by the tested immunogen in all Brown Latvian calves for 6 months and in 70% of the Black and White calves.
Asunto(s)
Leucosis Bovina Enzoótica/prevención & control , Virus de la Leucemia Bovina , Animales , Anticuerpos Antivirales/sangre , Antígenos Virales/administración & dosificación , Antígenos Virales/aislamiento & purificación , Bovinos , Leucosis Bovina Enzoótica/inmunología , Leucosis Bovina Enzoótica/microbiología , Estudios de Evaluación como Asunto , Inmunización , Virus de la Leucemia Bovina/inmunología , Virus de la Leucemia Bovina/aislamiento & purificación , Activación de Linfocitos , Linfocitos/inmunología , Linfocitos/microbiología , Especificidad de la Especie , Proteínas Virales/administración & dosificación , Proteínas Virales/inmunología , Proteínas Virales/aislamiento & purificaciónRESUMEN
Poly(A)-containing RNAs were extracted directly from the culture fluid of BLV-producing continuous and short-term lymphocyte cultures. The abovesaid poly(A)-RNAs were used as a template to synthesize complementary [3H]DNA (BLV cDNA). BLV cDNA possessed a high degree of homology to poly(A)-RNA isolated directly from the blood plasma of a leukemic animal. In contrast of leukemic cattle BLV-related sequences in white blood cells of normal animals were absent. Leukemic cells of cattle with both, spontaneous and experimentally induced leukemia contained bovine leukemia virus sequences in their genomes.
Asunto(s)
Enfermedades de los Bovinos/microbiología , Leucemia/veterinaria , Animales , Secuencia de Bases , Bovinos , Enfermedades de los Bovinos/sangre , Células Cultivadas , Complemento C3/biosíntesis , ADN Viral/biosíntesis , Genes Virales , Técnicas In Vitro , Virus de la Leucemia Bovina , Linfocitos/microbiología , Hibridación de Ácido Nucleico , Poli A/aislamiento & purificación , ARN Viral/aislamiento & purificaciónRESUMEN
The data are presented concerning the induction of bovine leukemia with purified and concentrated C-type oncornaviruses isolated from cattle of Latvian Brown breed with persistent lympholeukemia. The calves induced with C-type oncornaviruses were found to have early signs of persistent lympholeukemia. Pathohistological changes suggesting persistent lympholeukemia were observed to precede early clinical and hematological signs of the disease. C-type oncornaviruses were reisolated from blood plasma of calves with experimentally induced lympholeukemia.