ABSTRACT
We determined whether drug-resistant variants of HIV-1 could be isolated from the peripheral blood mononuclear cells of 20 individuals with HIV infection (Centers for Disease Control groups II and III) on long-term zidovudine (AZT) therapy. Toward this end, zidovudine (10 microM) has been included in the tissue culture medium used to isolate HIV-1. Under these circumstances, virus with a zidovudine-resistant phenotype was successfully obtained in five out of 20 cases. This property of drug resistance appeared to be stable, and did not disappear upon extended replication of such virus in the absence of drug pressure. Drug-resistant virus could also be isolated from these subjects on subsequent occasions, but was not present in samples obtained prior to therapy. Replication of these zidovudine-resistant isolates in tissue culture was inhibited by each of four other nucleoside analogues. Thus, other drugs may be useful in controlling selective zidovudine-resistant variants of HIV-1.
Subject(s)
HIV/isolation & purification , Zidovudine/pharmacology , Acquired Immunodeficiency Syndrome/drug therapy , Drug Resistance, Microbial , HIV/drug effects , HumansABSTRACT
Cytomegalovirus (CMV) has often been cited as a cause of immune suppression in children, yet little is known of the mechanisms through which this agent might affect immune function. We have succeeded in using CMV to productively infect cultured human fetal and infantile thymic epithelial (TE) cells. Morphological changes were apparent by 2-4 days after viral inoculation. CMV-related early antigen (EA) and late antigen (LA) were detected by immunofluorescence after 8 days, and progeny infectious CMV was recovered from culture media after 12-17 days. TE cells that reacted with monoclonal antibodies specific for keratin and for GQ ganglioside were predominant throughout the culture period. In contrast, infection by CMV resulted in a significant decrease in numbers of cells reactive with monoclonal antibodies specific for mesoderm-derived components. Inoculation of TE cells with CMV also caused a diminution in levels of detectable interleukin-1 (IL-1)-related antigen by 17 days after infection.
Subject(s)
Cytomegalovirus/growth & development , Thymus Gland/microbiology , Virus Replication , Animals , Antibodies, Monoclonal/immunology , Antigens, Viral/analysis , Child, Preschool , Cytomegalovirus/immunology , Epithelium/microbiology , Female , Fetus , Fluorescent Antibody Technique , Gangliosides/analysis , Humans , Infant , Interleukin-1/analysis , Keratins/analysis , Mice , PregnancyABSTRACT
Cultures of human thymic epithelial (TE) cells are able to produce a interleukin 1 (IL-1) like activity. This IL-1 activity can be detected either using mouse thymocytes in a traditional IL-1 assay, or using thymic lymphocytes obtained from cases of pediatric cardio-vascular surgery. Production of IL-1 activity by TE cells was found to be maximal between 3 and 4 weeks after culture initiation. Human thymocytes worked best as targets in an IL-1 assay, when these cells were derived from donors younger than 1 year of age. Infection of human TE cells by any of human cytomegalovirus, herpes simplex virus type 2, adenovirus 7, Coxsackie B1, and respiratory syncytial virus led to marked reductions in the ability of these cells to secrete measurable IL-1 activity. In the case of TE cells infected by cytomegalovirus, respiratory syncytial virus, and Coxsackie B1, this abrogation of production of IL-1 activity occurred in the absence of any obvious virus-induced cytopathic effect.
Subject(s)
Interleukin-1/biosynthesis , Thymus Gland/immunology , Virus Diseases/immunology , Cells, Cultured , Child , Child, Preschool , Cytomegalovirus Infections/immunology , Cytomegalovirus Infections/microbiology , Epithelium/microbiology , Humans , Infant , Thymus Gland/microbiology , Virus Diseases/microbiologyABSTRACT
Human cytomegalovirus (CMV), when added to cultures of either thymic or peripheral blood lymphocytes, was able to prevent these cells from responding to mitogenic stimulus. This effect was only obtained when live virus was utilized, and is apparently dependent on the ability of such virus to establish abortive infections in the cell cultures. CMV-infected cultures became deficient in terms of ability both to produce interleukin-2 (IL-2) activity as well as to respond to purified, recombinant IL-2 which was added exogenously. Similar results were obtained using either a laboratory strain (AD-169) of CMV or freshly-obtained clinical isolates of this virus which had been grown in tissue culture.
Subject(s)
Cell Transformation, Viral/immunology , Cytomegalovirus/genetics , Lymphocyte Activation , Lymphocytes/immunology , T-Lymphocytes/immunology , Adult , Cells, Cultured , Child , Humans , Interleukin-2/pharmacology , Lymphocytes/drug effects , MitogensABSTRACT
Yersinia enterocolitica strains that exhibited a calcium requirement for growth and autoagglutination at 37 degrees C were invariably virulent in rabbits, causing diarrhea and a high degree of lethality, and were capable of colonizing the intestinal lumen and establishing foci of infection on the Peyer's patches of mice. Strains that had lost the properties of calcium dependency and autoagglutinability were totally avirulent in rabbits and were quickly eliminated from the intestinal lumen and tissues of mice. Virulent and avirulent strains were shown to be equally invasive to HeLa cells. However, the virulent strains were resistant to the bactericidal action of normal serum, and this serum resistance was lost with the loss of virulence. Furthermore, the serum resistance of virulent strains was expressed, as were other properties, when strains were grown at 37 degrees C, but not at 27 degrees C. These results suggest that a virulence factor associated with serum resistance plays an essential role in the pathogenicity of Y. enterocolitica.