Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0393754 (HSA)
 2,996 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

HBsAg is known to bind to human serum albumin polymerized by glutaraldehyde, human serum albumin has been found in preparations of HBsAg by several investigators. However, it is not yet known whether natural human serum albumin binds to hepatitis B virus under physiological conditions. We studied the binding between natural or recombinant HBsAg and monomeric human serum albumin by immunological, biochemical and biophysical methods. The binding capacity of 20-nm HBs spheres was variable but ranged up to six molecules HSA/sphere. A reversible binding site for human serum albumin was exclusively localized in the preS2 domain, whereas the S domain was inactive in vitro. Human serum albumin copurified with HBsAg of human origin during gel chromatography or sucrose-gradient centrifugation. This human serum albumin was monomeric in sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The preS2-bound part of the human serum albumin could be removed from HBsAg by high-salt, such as CsCl centrifugation, but another part could only be removed by treatment with a disulfide cleaving reagent. Most of this covalently bound human serum albumin was retained at the HBsAg particle after complete cleavage of medium-sized HBs protein with trypsin. This indicates a second way in which albumin binds irreversible to cysteine(s) of the small HBs protein (SHBs, P24 and GP27).
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PMID:Interaction between hepatitis B surface proteins and monomeric human serum albumin. 216 67

Human epithelial cells (L132) derived from embryonic lung and human lung fibroblasts (MRC5) were infected by human immunodeficiency virus type 1 (HIV-1) or type 2 (HIV-2). Surface CD4 protein was detected on these cells, and recombinant soluble CD4 (sCD4) blocked infection, indicating that HIV infection was mediated by the cell surface CD4 protein. In contrast, infection of human primary chondrocyte cells (C23), synovial cells (HSA), and foreskin fibroblasts (F13) was apparently independent of cell CD4-mediated mechanisms. Surface CD4 protein could not be detected on these cells, and sCD4 did not block the infection. F13 cells could be infected only by HIV-2, not by HIV-1, under our experimental conditions. In cells of mesenchymal orgin, viral production could be detected only after cocultivation with the human T-lymphoid H9 cells but not by conventional viral assays, including reverse transcriptase and p24 antigen assays in cell culture supernatant and immunofluorescence of host cells. Our DNA transfection studies indicated that this lack of detectable viral production was not due to the inefficient use of the HIV long terminal repeat or the Tat protein in these cells. These mesenchymal and epithelial cells were susceptible to HIV infection but differed in mechanism of virus entry compared with hematopoietic cells such as T lymphocytes. These observations may provide insights into clinical syndromes such as lung dysfunction in HIV-infected newborns and connective tissue disorders in HIV-infected adults.
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PMID:Infection of nonlymphoid cells by human immunodeficiency virus type 1 or type 2. 238 19

Two strains of human immunodeficiency virus type 1 (HIV-1) expressing different reporters, human placental alkaline phosphatase (PLAP) and murine heat stable antigen (HSA, CD24), were used for dual infection. Flow cytometric analysis enabled us to distinguish cells not only infected with individual reporter virus but also superinfected with both reporter viruses. When the CD4 positive T cell line, PM1, was dually infected by both reporter viruses with different coreceptor utilization, coinfection with CXCR4-tropic HIV-1 (X4 HIV-1) expressing one reporter increased the rate of cells infected with HIV-1 expressing another reporter. This enhancement was accompanied by an increased level of p24 antigen Gag in culture supernatant, indicating that infectivity of HIV-1 was augmented by X4 HIV-1 coinfection. The CXCR4 antagonist, T140 eliminated this enhancement, suggesting the role of X4 envelope via CXCR4. These results imply the role of X4 HIV-1 at the late stage of infection.
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PMID:Enhanced infectivity of HIV-1 by X4 HIV-1 coinfection. 1292 5