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Biomedical subjects

F Dorner

Publications and source records attributed to F Dorner.

At least 91 records · Page 5Linked to original sources
PubMed1993

At what stage should virus inactivation be carried out?

On an industrial scale blood products are produced from plasma pools consisting of donations from thousands of donors. As a number of pathogens may be present in the donor before symptoms of an infectious disease become evident, such pathogens, particularly viruses, may be transmitted in human blood products. The level of virus contamination can be substantially reduced by a range of serological tests and by polymerase chain reaction screening. Viruses can also be removed and/or inactivated during the course of the plasma fractionation process. However, specific virus inactivation steps must be included in the manufacturing process for most blood products. The stage at which these steps should be introduced and the efficacy and drawbacks of various procedures are described.

Biological Products↗
PubMed1993

Minimum safety requirements for preclinical testing.

A wide range of biological products for medicinal use can now be produced by novel biotechnology processes. These products include naturally occurring human proteins and peptides such as hormones, cytokines, blood products as well as monoclonal antibodies of murine and human origin and bacterial and viral antigens for use as vaccines. However, there are potential safety concerns that arise from the novel processes used in their manufacture and from the complex structural and biological characteristics of the products. The acute and repeated dose toxicity testing, pharmacodynamic and immunological testing and a range of product-specific biochemical and safety tests required for these products are described.

Animals↗
PubMed1992

Construction of chimeric vaccinia viruses by molecular cloning and packaging.

Foreign DNA was inserted into unique restriction endonuclease cleavage sites (Sma I or Not I) of the 200,000-base-pair vaccinia virus genome by direct molecular cloning. The modified vaccinia virus DNA was packaged in fowlpox virus-infected avian cells, and chimeric vaccinia virus was isolated from mammalian cells not supporting the growth of the fowlpox helper virus. In contrast to the classical "in vivo" recombination technique, chimeric viruses with inserts in both possible orientations and families of chimeras with multiple inserts were obtained. The different genomic configurations of chimeric viruses provide a broader basis for screening of optimal viruses. In addition to packaging in avian cells, a second packaging procedure for vaccinia DNA, based on the abortive infection of mammalian cells with the fowlpox helper virus, was developed. This procedure permits simultaneous packaging and host-range selection for the packaged virus. The cloning/packaging procedure allows the direct insertion of foreign DNA without the need for plasmids having flanking regions homologous to viral nonessential regions and is independent of inefficient in vivo recombination events. By direct cloning and packaging, about 5-10% of the total vaccinia virus yield consisted of chimeras. The procedure is, therefore, a useful tool in molecular virology.

Animals↗
PubMed1991

Immunization of chimpanzees with the HIV-1 glycoprotein gp160 induces long-lasting T-cell memory.

The goal of the present study was to investigate the antigen-specific T-cell response to the recombinant HIV envelope glycoprotein (gp160) and to test the effect of various adjuvant formulations on the efficiency of T-cell priming as well as on magnitude and longevity of the gp160-specific T-cell response. Our studies revealed that, in combination with an appropriate adjuvant (lipid-based adjuvant or mineral carrier complex), immunization with recombinant gp160 led to the appearance of gp160-primed T cells. The T-cell response obtained was substantial (proliferative response of greater than 100,000 delta dpm after one primary and two booster immunizations), gp160-specific (proliferation only in response to gp160, no proliferation after addition of a mock gp160 preparation), and long-lasting (T cell responses of greater than 50,000 delta dpm were observed more than one year after the last booster). The results presented here differ from those of previous studies in that they show the presence of substantial and long-lasting T-cell memory toward the immunogen gp160. Therefore further investigations on the use of these preparations as HIV candidate vaccines appear to be justified.

Adjuvants, Immunologic↗
PubMed1991

Characterization of a vaccinia-derived recombinant HIV-1 gp160 candidate vaccine and its immunogenicity in chimpanzees.

The human immunodeficiency virus (HIV-1) envelope glycoprotein gp160 was produced in large-scale microcarrier cultures of Vero cells, using a system involving coinfection with two recombinant vaccinia viruses. The immunogenicity of this material was studied in conjunction with a number of different adjuvant formulations, and chimpanzees were then immunized with gp160 in conjunction with Al(OH)3, Al(OH)3 and sodium deoxycholate, and a lipid-based adjuvant. The Al(OH)3-gp160 vaccine formulation elicited very poor immune responses in two chimpanzees, and these animals were further immunized with gp160 in conjunction with a lipid-based adjuvant. Immunization with the latter formulation lead to induction of high-titer neutralizing antibodies, and, following challenge with HIV-1, one chimpanzee demonstrated no evidence of virus infection over a period of 3 years. The second chimpanzee, which had previously been infected with non-A, non-B hepatitis, and two animals immunized with gp160 with Al(OH)3 and deoxycholate were not protected against challenge.

AIDS Vaccines↗
PubMed1990

[AIDS vaccines: an enigma in vaccine development].

The principles of viral vaccine development and the immune responses to vaccination are described. An effective vaccine should stimulate both cellular and humoral immune responses to provide lasting protection against infection and disease. We describe specific problems associated with the development of an AIDS vaccine i.e. lack of experience with human retroviruses, the integration of the HIV genome in cellular DNA, HIV infection of critical cells in the immune system, persistence of HIV in the brain, large variations in the virus envelope gene, immune interactions with the CD-4 protein and the generation of infection enhancing antibodies. The strategies of AIDS vaccine development are discussed and the candidate vaccines are described with a report on the status of each vaccine trial in progress.

Acquired Immunodeficiency Syndrome↗
PubMed1989

[Comparison of virus isolation and antigen enzyme immunoassay in the detection of HIV].

Virus isolation from peripheral blood lymphocytes and antigen detection in serum by ELISA were compared in 75 patients with a serologically confirmed HIV infection. 25 per cent of the lymphocyte cultures were HIV positive, but only 2 of the 14 patients were also antigen positive. In addition, infectious virus was not detected in 15 antigen positive patients, thus revealing only a low degree of correlation between the two assay systems.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Efficiency of the polymerase chain reaction for the detection of human immunodeficiency virus type (HIV-1) DNA in the lymphocytes of infected persons: comparison to antigen-enzyme-linked immunosorbent assay and virus isolation.

Seventy-one human immunodeficiency virus type (HIV-1)-positive patients were investigated by polymerase chain reaction (PCR), virus isolation, and antigen detection for the existence of HIV in blood. The identification of HIV DNA by PCR, using three different pairs of primers, yielded a clearly higher detection rate (86%) than with two primer pairs (75%) and was far more sensitive than virus isolation (45%) and antigen ELISA (14%). The PCR-negative results were clearly correlated to asymptomatic clinical stages. However, there was a limited correlation between the clinical stage of disease and the amount of HIV DNA that could be detected in equal numbers of CD4+ cells from different patients, which might be due to their treatment with azido-thymidine (AZT).

Acquired Immunodeficiency Syndrome↗
PubMed1989

Large-scale production and purification of a vaccinia recombinant-derived HIV-1 gp160 and analysis of its immunogenicity.

The human immunodeficiency virus (HIV-1) envelope gene was expressed in large-scale microcarrier cultures of Vero cells using a system involving coinfection with two recombinant vaccinia viruses. One recombinant contained the bacteriophage T7 RNA polymerase gene under control of a vaccinia virus promoter. The second contained the HIV-1 gp160 gene flanked by T7 promoter and termination sequences. The protein was expressed on the surface of infected cells, and it was shown to have a molecular weight of 160 kD and to react with gp41 and gp120 specific monoclonal antibodies. After purification by successive affinity and ion-exchange chromatography, the protein was demonstrated to be present in a particulate form with a diameter in the range of 15-30 nm. When injected into goats a high-titer gp160 specific antibody response was elicited and group-specific neutralizing activity could be demonstrated in vitro. The immunogenicity of the protein was also studied in conjunction with a number of adjuvant formulations, and the highest potency in mice was obtained using a preparation with 0.2% Al(OH)3 and 0.25% deoxycholate.

Adjuvants, Immunologic↗
PubMed1988

Cell-mediated immune response toward viral envelope and core antigens in gibbon apes (Hylobates lar) chronically infected with human immunodeficiency virus-1.

The specific cellular immune response toward envelope and core proteins of human immunodeficiency virus-1 (HIV-1) was investigated in gibbon apes chronically infected with the HTLV-IIIB isolate. After in vitro stimulation of PBMC from infected and control animals with HIV-1 Ag, DNA synthesis, IL-2R expression and IL-2 release were assayed. Cells from infected gibbon apes demonstrated a group-specific response toward whole virus preparations from three divergent HIV-1 isolates (HTLV-IIIB, HTLV-IIIRF, HTLV-IIIMN). Consistent responses were also detected against purified HIV-1 Ag, i.e., native gp120 envelope glycoprotein, recombinant gp160 glycoprotein, a synthetic peptide (peptide 7) representing a highly conserved region of gp120, and purified native core protein p24. In addition, lymphocytes from infected gibbon apes displayed a specific, MHC-restricted, cytotoxic activity against autologous cells expressing HIV-1 envelope or gag proteins. The specific T cell reactivity toward HIV-1 proteins observed in infected gibbons contrasts with findings in HIV-1 infected humans, and may help to explain the apparent discrepancy in the natural history of the infection between the two species.

Acquired Immunodeficiency Syndrome↗
PubMed1988

Production and quality assurance of Lys-plasminogen steam treated.

A highly purified plasminogen concentrate, LYS-PLASMINOGEN Steam Treated, has been developed for thrombolytic therapy of arterial and venous occlusions in combination with fibrinolytic agents. In search of a highly efficient drug covering this indication, we decided to select the lys-form of plasminogen because of its higher affinity to fibrin in contrast to the glu-form. This property of lys-plasminogen also led us to expect an improved thrombolytic activity as opposed to other forms of the proenzyme. The intermediate product is manufactured from pooled human citrated plasma by ethanol fractionation after separation of coagulation factor proteins. Further processing includes specific transformation and purification steps. The final product is a freeze-dried preparation characterized by a high specific activity greater than or equal to 18.0 CU/mg protein and a content of lys-plasminogen of greater than or equal to 95%. To reduce the risk of viral infections, the plasma pool includes only plasma donations which are ALT tested and negative for HBsAg and anti-HIV. In addition the intermediate freeze-dried bulk powder is subjected to a virus inactivation procedure based on steam treatment for 10 hours under standardized product specific conditions without using special protein stabilizers. Physical parameters of steam treatment provide for a maximum virus killing effect without impairing the biological plasminogen activity or changing the molecular integrity of the product. In a preclinical test HIV was inactivated by 6 log 10 after 3 hours of steam treatment leaving a 7 hour safety margin for inactivation of more heat resistant viruses.(ABSTRACT TRUNCATED AT 250 WORDS)

Acquired Immunodeficiency Syndrome↗
PubMed1987

Perspectives of HIV vaccine developments.

Human immunodeficiency virus type 1 (HIV-1) may enter the blood stream as free virus or via infected lymphocytes, which poses problems for vaccine development. The classical vaccine designs, attenuated, inactivated, or subunit vaccine will be discussed with regard to HIV. Development of a recombinant subunit vaccine appears to be the most promising approach. Forthcoming results from experiments involving inoculation of chimpanzees should allow evaluation of the feasibility of using a subunit vaccine based on the env-glycoprotein. Also the use of live recombinant vaccinia merits further investigation.

Animals↗
PubMed1986

Impaired primary, but not secondary, immune response in breast cancer patients under adjuvant chemotherapy.

The antibody response after vaccination against tick-borne encephalitis (TBE) was studied in patients with breast cancer. Although sex- and age-matched control persons produced high titers of anti-TBE antibodies 2 to 4 weeks after the second of two consecutive vaccinations, patients with breast cancer who were first vaccinated after the start of adjuvant chemotherapy consisting of cyclophosphamide, methotrexate and 5-fluorouracil (CMF) failed to do so. The lack of anti-TBE antibody production was found not only in patients under CMF chemotherapy, but also in those primarily vaccinated 6 to 12 months after the termination of CMF treatment. Patients with breast cancer who had been vaccinated either before or after the onset of disease, but before the initiation of chemotherapy, were shown to have developed significant anti-TBE antibody titers which persisted throughout the course of adjuvant treatment and could be boostered by revaccination during the course of CMF administration. The authors conclude that patients with breast cancer undergoing adjuvant chemotherapy experience a serious and prolonged defect in primary antibody production, whereas secondary immune responses remain unimpaired.

Adult↗
PubMed1986

[Molecular biology of human T-lymphotropic retroviruses (HTLV)].

The first human retroviruses have been discovered during the past seven years. They cause two diseases which involve disturbances of the growth of the T4-lymphocyte. This target cell type, which is central to the regulation of the immune system is induced by human T-lymphotropic virus type I (HTLV-I) to excessive proliferation (leukaemia) and by HTLV-III/LAV (lymphadenopathy associated virus) to premature death (acquired immune deficiency syndrome [AIDS]). Both also seem to be indirectly involved in several other disorders. The genetic structures of these retroviruses and the mechanisms by which they usurp host-cell functions are novel among retroviruses. The continuous increase in the number of AIDS cases for whom no effective therapy is currently possible mandates attempts at developing primary prevention by a vaccine. Based on past attempts at developing vaccines against retroviruses, the most feasible configuration will be the glycoprotein linked to its transmembrane protein. Any virus preparation containing nucleic acids could be considered less safe. Potential problems exist in that there is extensive heterogeneity among various HTLV-III isolates, particularly in the env-gene. This fact and the known relationship of HTLV-III to some Lentiviruses suggest that functional antigenic variation could be encountered. The methodology of developing a vaccine against the retroviruses causing AIDS should also be helpful in designing vaccine strategies against human leukaemia and lymphomas caused by other members of this virus family.

Acquired Immunodeficiency Syndrome↗