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Biomedical subjects

G Galfrè

Publications and source records attributed to G Galfrè.

At least 19 recordsLinked to original sources
PubMed1999

Antibody responses to hepatitis C virus hypervariable region 1: evidence for cross-reactivity and immune-mediated sequence variation.

Sequence heterogeneity of hepatitis C virus (HCV) is unevenly distributed along the genome, and maximal variation is confined to a short sequence of the HCV second envelope glycoprotein (E2), designated hypervariable region 1 (HVR1), whose biological function is still undefined. We prospectively studied serological responses to synthetic oligopeptides derived from HVR1 sequences of patients with acute and chronic HCV infection obtained at baseline and after a defined follow-up period. Extensive serological cross-reactivity for unrelated HVR1 peptides was observed in the majority of the patients. Antibody response was restricted to the IgG1 isotype and was focused on the carboxyterminal end of the HVR1 region. Cross-reactive antibodies could be readily elicited following immunization of mice with multiple antigenic peptides carrying HVR1 sequences derived from our patients. The vigor and heterogeneity of cross-reactive antibody responses were significantly higher in patients with chronic hepatitis compared with those with acute hepatitis and in patients infected with HCV type 2 compared with patients infected with other viral genotypes (predominantly type 1), which suggest that higher time-related HVR1 sequence diversification previously described for type 2 may result from immune selection. The finding of a statistically significant correlation between HVR1 sequence variation, and intensity, and cross-reactivity of humoral immune responses provided stronger evidence in support of the contention that HCV variant selection is driven by the host's immune pressure.

Adolescent↗
PubMed1997

Immunogenicity of filamentous phage displaying peptide mimotopes after oral administration.

Selected human sera can be used to identify disease-related peptide epitopes (mimotopes) displayed on bacteriophages. Parenteral administration of such recombinant phages is an effective route of immunization in different experimental animals, indicating that mimotopes could be an important source of leads for new vaccines. Here it is shown that intranasal or intragastric administration of phage in mice induces an immunological response both to the wild type proteins of the phage and to mimotopes displayed on them. Using mimotopes of human HBV surface antigen and of human HCV peptides, the authors show that the response induced by oral administration is specifically cross-reactive with the original antigen. These findings indicate that phage displaying selected mimotopes could be useful for the development of orally effective vaccines.

Adjuvants, Immunologic↗
PubMed1996

Selection of antigenic and immunogenic mimics of hepatitis C virus using sera from patients.

Using sera from hepatitis C virus (HCV)-infected patients and noninfected subjects to screen random peptide libraries displayed on phage, we selected peptides specifically reacting with sera from infected patients. These phage- borne peptides were shown to mimic distinct HCV determinants. They detected in all cases the presence of anti-HCV Abs in a large panel of patients' sera, thus demonstrating the high sensitivity of the selected peptides as diagnostic markers. In addition, this diagnostic approach allowed a detailed characterization of the individual humoral response to viral infection. Phage-displayed HCV mimics were substitutes for the authentic HCV epitopes in inducing a strong specific response against HCV when used as immunogens in mice. These results support the search for HCV mimics with the potential to elicit a protective immune response as leads for the development of a mimotope-based vaccine against viral infection.

Amino Acid Sequence↗
PubMed1996

Selection of biologically active peptides by phage display of random peptide libraries.

Random peptide libraries displayed on phage are used as a source of peptides for epitope mapping, for the identification of critical amino acids responsible for protein-protein interactions and as leads for the discovery of new therapeutics. Efficient and simple procedures have been devised to select peptides binding to purified proteins, to monoclonal and polyclonal antibodies and to cell surfaces in vivo and in vitro.

Animals↗
PubMed1995

Derivation of vaccines from mimotopes. Immunologic properties of human hepatitis B virus surface antigen mimotopes displayed on filamentous phage.

We have previously reported the identification, using human immune sera, of mimotopes of human hepatitis B virus surface Ag (HBsAg) displayed on filamentous phage. To test if these mimotopes could be useful in developing a vaccine against the human hepatitis B virus (HBV), we have compared the humoral immune response of animals immunized either with a recombinant HBsAg vaccine, or with mimotopes. Immunogens were prepared by fusing the mimotopes on different carrier molecules (phage coat protein pIII and pVIII, recombinant human H ferritin, HBV core peptide) and by synthesizing multiple antigenic peptides carrying the mimotopes' amino acid sequences. These immunogens were injected into mice and rabbits and sera were collected and tested for the presence of HBsAg-specific Abs. Our data confirm that mimotopes can induce a humoral immune response resembling that induced by the original Ag, and HBsAg mimotopes displayed on phage prove to be the best immunogens, inducing the most reproducible and potent immunization. Mimotopes that react as HBV subtype-specific Ags do not show this specificity as immunogen and induce a nonsubtype-restricted response. Furthermore, mimotopes displayed on phage elicit a strong response to HBsAg in a strain of mouse reported to show a low response to it. These results indicate that mimotopes identified from random peptide libraries through utilizing human immune sera could be important leads for the derivation of new vaccines.

Amino Acid Sequence↗
PubMed1987

Monoclonal antibody ELISA to quantitate wheat gliadin contamination of gluten-free foods.

A sensitive reproducible monoclonal antibody-based sandwich ELISA has been developed to measure the gliadin content of foods. Using the assay we have confirmed that nominally gluten-free products based on wheat starch contain trace amounts of gliadin. The level of gliadin contamination in these foods is sufficient to cause relapse of coeliac disease in specific patients. We have also examined the cross-reactivity of different cereal proteins in the assay and found good correlation with their known toxicity to patients with coeliac disease.

Animals↗
PubMed1982

Chemical typing of human kappa light chain subgroups expressed by human hybrid myelomas.

Hybrids between human spleen cells and the non-secretor NSO mouse myeloma, and also between the rat non-secretor line YB2/O and human peripheral blood cells were prepared. After a month in culture very few hybrids retained the ability to secrete the human kappa light chain. From these, clones could be derived which remained stable over several months of continuous culture. On incorporating [3H]-Leu into the culture medium the cells secrete large amounts of radioactive light chain. It is shown that, even without dialysis, the purity of the preparation is sufficient for an automatic N-terminal sequence analysis at the radioactive level. From the pattern of distribution of leucine in the first twenty-two amino acid residues, it is possible to assign the synthesized light chains to one of the four established human subgroups. The method permits a fast and simple classification of human light chains secreted by hybrid myelomas. Although tested with rodent x human hybrids, we see no reason why the method could not equally apply to human x human hybrids.

Animals↗
PubMed1980

H 9/25 monoclonal antibody recognizes a new allospecificity of mouse lymphocyte subpopulations: strain and tissue distribution.

C3 H/He-mg mice were immunized with C57BL/10 (B10) spleen cells and the immune spleen cells were fused with BALB/c myeloma cells (NS1). One of the monoclonal antibodies (H9/25 antibody) produced by the hybrid cells was studied. It reacts with subpopulations of B10 lymphocytes as well as some lymphoid tumor lines including some of the Abelson virus-induced leukemias. The antigen recognized by H9/25 antibody is expressed on lymphocytes from all the B10 congeneic mice tested as well as some other strains of mice. No linkage between genes coding for the antigen and H-2 loci was found as judged by its presence on cells of the B10 strains regardless of H-2 type and the distribution of the antigen on Bailey recombinant inbred mice. The antigen is expressed on subpopulations of lymph node cells, spleen cells, thymocytes and bone marrow cells. The strain distribution of the H9/25 antigen seems to be identical to that of Ly-6, Ly-8 and Ala-1 antigens. However, the tissue distribution of the antigen recognized by H9/25 antibody, while similar to these alloantigens, is unique and the antigen may be distinct from the other alloantigens.

Animals↗
PubMed1980

Isolation of six monoclonal alloantibodies against rat histocompatibility antigens: clonal competition.

We describe the isolation of six clones and some variant derivatives of rat x mouse hybrid myelomas secreting alloantibody against antigens of the rat major histocompatibility complex. Very large numbers of active hybrids were obtained but many were lost early in the post-fusion period; evidence is presented for rapid selective processes operating in uncloned complex hybrid cultures. The results suggest that the secretion of specific immunoglobulin chains is as stable a function in rat x mouse hybrid myelomas as in mouse x mouse hybrid myelomas.

Animals↗
PubMed1978

Monoclonal xenogeneic antibodies to murine cell surface antigens: identification of novel leukocyte differentiation antigens.

Hybrid myeloma cell lines secreting monoclonal antibodies to mouse cell surface antigens have been prepared. Spleen cells from a DA rat immunized with B10 mouse spleen cells that had been enriched for T cells were fused to cells from a nonsecreting mouse myeloma line (NSI). The presence in the culture supernatants of antibodies binding to mouse spleen cells was tested by a binding assay with 125I-labeled anti-rat IgG. From a large number of positive cultures, ten independent hybrid clones were purified, each secreting a different antibody. Each antigenic target was analyzed by (a) gel electrophoresis of immunoprecipitated 125 I-labeled cell surface molecules, (b) heat stability, (c) strain and species distribution and (d) cross-inhibition of binding of different monoclonal antibodies. It was concluded that the ten monoclonal antibodies regognized four types of antigen. One was the heterophile, heat-stable, Forssman antigen. The second (mol.wt. 210 000) appears to be a major 125I-labeled lymphoid cell surface protein. The third, a minor component of spleen cells, was precipitated as two polypeptides of mol.wt. 190 000 and 105 000. Five IgG-secreting clones identify the fourth antigen, a heat-stable, possibly glycolipid component expressed on mouse red blood cells and also on thymocytes. Cross-inhibition studies suggest that these last monoclonal antibodies bind to overlapping, but not identical, determinants. The class and chain composition of the monoclonal antibodies were studied by gel electrophoresis, isoelectric focusing and ability to lyse red blood cells and thymocytes.

Animals↗
PubMed1978

Monoclonal antibodies as probes for differentiation and tumor-associated antigens: a Forssman specificity on teratocarcinoma stem cells.

A set of monoclonal antibodies derived by fusing P3-NS1/1-Ag4-1 myeloma cells with spleen cells from a rat immunized with mouse spleen were screened for activity against a tumor cell panel. One of these antibodies was found to react only with mouse embryonal carcinoma cells and no other tumor cell type tested, including differentiated derivatives of teratocarcinomas. In the adult mouse, this antigen is expressed by subpopulations of cells in the spleen, bone marrow, lymph node, brain, kidney and testes, although not in liver and thymus. This antigen has a species and tissue distribution consistent with that of Forssman antigen. The molecules which carry this specificity on the embryonal carcinoma cells appear to be glycolipids.

Antibodies↗
PubMed1977

A myeloma hybrid producing antibody specific for an allotypic determinant on "IgD-like" molecules of the mouse.

A hybrid cell line was produced by fusing a mouse myeloma line with spleen cells from BALB/c mice immunized with B10 cells. The hybrid line grew in tissue culture and in syngeneic mice and produced IgM antibody specific for "IgD-like" molecules of mice with the Igb haplotype. The concentration of monoclonal antibody in the serum of tumor-bearing animals reached about 2 mg/ml and gave cytotoxic titers of up to 1:800 000. The derivation of the line, some properties of the antibody secreted and the nature of its antigenic target are described.

Animals↗