RESUMEN
Specimens obtained from feline leukemia virus (FeLV)-positive cats were examined for infectious FeLV. Feline leukemia virus was detected by a focus-forming assay and confirmed by florescent antibody. Techniques of sample processing were evaluated and adjusted for optimum detection of FeLV. Low levels of FeLV were detected in 2 of 10 oral samples; however, the majority of these samples (17 of 27 tested) produced cytopathic effects in tissue culture which prevented Fe LV detection. Three of 24 urine samples and 1 of 20 rectal specimens were positive for FeLV. One milk sample contained high levels of FeLV.
Asunto(s)
Enfermedades de los Gatos/microbiología , Virus de la Leucemia Felina/aislamiento & purificación , Animales , Sangre/microbiología , Gatos , Efecto Citopatogénico Viral , Femenino , Virus de la Leucemia Felina/crecimiento & desarrollo , Virus de la Leucemia Felina/inmunología , Masculino , Leche/microbiología , Boca/microbiología , Orina/microbiologíaRESUMEN
A rapid and sensitive radioimmunoassay for the detection of soluble Yersinia pestis fraction I antigen using antibody-coated beads and radiolabeled immunoglobulin was applied to spleen-liver extracts, rendered noninfectious by either treatment or filtration, from rodents dead of plague. The procedure was capable of detecting nanogram amounts of soluble plague antigen.
Asunto(s)
Antígenos Bacterianos/análisis , Radioinmunoensayo , Yersinia pestis/inmunología , Animales , Reacciones Cruzadas , RatonesRESUMEN
The role of the Yersinia pestis virulence-associated plasmid, pYV019, in the expression of Ca++ dependence, virulence, and the production of the V antigen was investigated. Derivatives of bacteriophage P1 were used to deliver the transposon Tn5 into Y pestis strain EV76. Ca++-independent mutants in which transposon Tn5 had been inserted into plasmid pYV019 were isolated, the resulting plasmids--pYV019::Tn5--were transformed into an Escherichia coli K12 derivative, and the site of insertion of transposon Tn5 was mapped with restriction endonucleases. The plasmids were then transduced by bacteriophage P1 into avirulent strain 195-P1 of Y pestis. The transductants were analyzed for expression of Ca++ dependence, virulence in mice, and the expression of the V antigen. Introduction of plasmid pYV019 with insertions outside of the Ca++ dependence loci restored strain 195-P1 to full virulence, while disruption of plasmid genes associated with Ca++ dependence led to loss of virulence. Using Western blotting analysis and E coli minicells, it was shown that genes specific for the V antigen are plasmid encoded.