ABSTRACT
Bartonella henselae is known to cause central nervous system (CNS) disease in humans, and neurological signs have been observed in experimentally infected cats. However, the pathogenesis of CNS disease remains unclear. This study was undertaken to determine whether B. henselae infects feline fetal brain cells in vitro. Microglial-cell- and astrocyte-enriched cultures were inoculated with B. henselae. Giménez staining identified bacterial organisms within microglial cells by day 7 postinoculation. The viability of the intracellular bacteria was demonstrated by incubating cultures with gentamicin and plating cell lysate on agar. Electron microscopy identified intracellular organisms with characteristic Bartonella morphology but identified no ultrastructural abnormalities within infected microglial cells. No evidence of infection was seen in Bartonella-inoculated astrocyte cultures. These findings suggest a role for microglia in the pathogenesis of B. henselae-associated neurological disease.
Subject(s)
Bartonella henselae/physiology , Brain/microbiology , Microglia/microbiology , Animals , Astrocytes/microbiology , Brain/cytology , Brain Diseases/etiology , Cats , Cells, Cultured , DNA, Bacterial/analysis , Female , Fetus/microbiology , Microscopy, Electron , PregnancyABSTRACT
Gibbon ape leukemia virus (GALV) enters cells following interaction with a specific receptor protein. We have isolated human complementary DNAs (cDNAs) encoding a protein which, when expressed in normally uninfectable mouse NIH3T3 cells, confers on these cells specific sensitivity to infection by GALV. This was done by transfection into mouse cells of human DNA and selection of putative receptor gene transfectants using infection with a retrovirus carrying a drug resistance gene. Transfected genomic sequences were then cloned through their association with repetitive DNA, and these were used to isolate cDNA clones. The predicted 679-amino acid sequence encoded in these cDNAs is characteristic of an integral membrane protein in that multiple potential transmembrane domains are present. Searches of DNA and protein data banks failed to reveal homologies to other known sequences. It thus appears that the sequence isolated is novel and represents the human receptor for GALV. As expected from the wide host range of the virus, closely related homologues of the gene were found in several other vertebrate species tested.
Subject(s)
Mice/genetics , Amino Acid Sequence , Animals , Base Sequence , Cell Line , DNA/genetics , DNA/isolation & purification , Fibroblasts/pathology , Genes , Genetic Predisposition to Disease , Humans , Mammals/genetics , Molecular Sequence Data , Protein Conformation , Receptors, Virus/genetics , Receptors, Virus/physiology , Recombinant Proteins/physiology , Sequence Homology, Nucleic Acid , Species Specificity , TransfectionABSTRACT
Using an oligonucleotide probe, we isolated cDNA clones corresponding to the precursor of the beta-amyloid peptide (BAP) from brain libraries of 3 patients with sporadic Alzheimer's disease (AD). DNA sequencing showed that the largest cDNA clone encompasses 83% of the open reading frame proposed by Kang et al. to encode the BAP precursor (APP). cDNA clones from each of the 3 AD brain libraries were identical to the sequence of the APP-cDNAs cloned from normal adult human and fetal brain. An antisense-radiolabeled RNA copy of one of the AD clones detected a pattern of 3 gene transcripts measuring 3.5, 3.2 and 1.6 kilobases (kb) in both normal and AD brain RNAs. These data suggest that there are no mutations in or about the 42 amino acid (aa) sequence of BAP and that the accumulation of amyloid consistently found in AD may result from altered post-translational processing of APP.
