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Biomedical subjects

G Hunsmann

Publications and source records attributed to G Hunsmann.

At least 145 records · Page 8Linked to original sources
PubMed1992

Immunization of rhesus monkeys with high- and low-dose Tween-ether-disrupted SIVMAC.

Two vaccine trials were conducted with low- and high-dose purified Twen-ether-treated SIVmac adsorbed onto aluminum hydroxide using rhesus macaques. In the first experiment 7 macaques were immunized with a total amount of 560 micrograms protein and 3 animals served as controls. After the immunization period the vaccinees exhibited ELISA titers up to 1:1280 and 5 immunized animals showed an antigen-specific proliferative response. After the virus challenge the 3 control animals and 3 vaccinees became infected. Four of the infected animals developed a cytotoxic T-cell response beginning 8 weeks postchallenge. The 4 protected animals were rechallenged 16 weeks later and all became infected. For the high-dose experiment 5 immunized animals receiving 2 mg of antigen and 2 control animals were used. The ELISA titers of the vaccinees reached 1:20480 and 4 animals exhibited an antigen-specific proliferative response. In response to virus challenge the 2 control and 1 immunized animal became infected. From these data it can be concluded that the high-dose immunization scheme elicited higher antibody titers and increased the fraction of protected animals.

Adjuvants, Immunologic↗
PubMed1992

Virus-specific cytotoxic T-lymphocytes in HIV-2-infected cynomolgus macaques.

OBJECTIVE: Specific cytotoxic T-lymphocytes (CTL) are induced in humans or monkeys after infection with HIV-1 or SIVmac, respectively. Since, like HIV-1, HIV-2 causes AIDS, our objective was to determine the characteristics of the HIV-2-specific CTL response. DESIGN: Since it is rarely possible to study cellular immunity in individuals, because of the small number of HIV-2-infected patients available in Europe and the necessity for co-operation in the performance of sequential CTL assays, cynomolgus macaques were infected with HIV-2. Autologous transformed B-lymphoblastoid cell lines infected with recombinant vaccinia viruses were used as target cells for cytotoxicity assays. METHODS: Recombinant vaccinia viruses expressing HIV-2 genes were constructed to infect B-lymphoblastoid cell lines from macaques. These cells were used as target cells for cytotoxicity assays with peripheral blood mononuclear cells from HIV-2BEN-infected cynomolgus macaques. To characterize the effector cells, CD8+ cells were separated with immunomagnetic beads. Major histocompatibility complex (MHC) restriction of the cytotoxic cells was determined by incubation with matched or mismatched target cells. RESULTS: HIV-2BEN-infected cynomolgus macaques raised CTL against proteins of the three major viral structural genes, gag, pol and env. The cytotoxic cells were CD8+ and their activity was MHC class I-restricted. In contrast to SIVmac-infected macaques, env-specific lysis was mediated exclusively by CD8+ cells. CTL from individual animals recognized different viral proteins and the recognition pattern varied over time. CONCLUSIONS: Like HIV-1 and SIVmac, HIV-2 induces virus-specific CTL. The variation of antigen recognition between individual animals and over time indicates that sequential experiments are necessary to determine the complete spectrum of the CTL response of infected animals. HIV-2-infected macaques represent a suitable model for investigations into the cellular immune response against HIV.

AIDS-Related Complex↗
PubMed1992

Identification of a gag protein epitope conserved among all four groups of primate immunodeficiency viruses by using monoclonal antibodies.

Five monoclonal antibodies (MAbs) were raised against the gag proteins of simian immunodeficiency virus (SIV) from African green monkey (SIVagmTYO-7). Two MAbs reacted with the matrix protein p17 and the other three with the core protein p24. Studies on the cross-reactivity of the MAbs revealed that the anti-p24 MAbs detected an epitope shared by the viruses belonging to the human immunodeficiency virus type 2 (HIV-2)/SIVmac group and SIVagmTYO-7 and SIVagmTYO-5. The anti-p17 MAbs recognized an epitope present on all these viruses and on SIVagmTYO-1, HIV-1 and SIVmnd. This finding demonstrates for the first time that the matrix protein, p17 or p18, respectively, of all nine HIV and SIV isolates tested in this study expresses at least one conserved immunogenic epitope recognized serologically. By using synthetic peptides, this epitope was identified at the N terminus of p17. Furthermore, this epitope was analysed by multiple sequence alignments of the peptide with homologous sequences of HIV and SIV p17.

Amino Acid Sequence↗
PubMed1992

Potential significance of the cellular immune response against the macaque strain of simian immunodeficiency virus (SIVMAC) in immunized and infected rhesus macaques.

The cellular immune response of seven rhesus macaques immunized with Tween-ether-treated macaque strain of simian immunodeficiency virus (SIVMAC) and three non-vaccinated control animals was investigated. Immunization elicited antigen-specific proliferating CD4+ cells in five of seven monkeys. Proliferating T cells were found in all animals protected from a first virus challenge. Cytotoxic T lymphocytes (CTLs) were not induced by the immunization. After the second challenge, the four formerly protected animals became infected, despite a strong proliferative CD4+ cell activity in three of them. All animals lost their proliferative activity 2 weeks after infection. After the first challenge four of the six infected animals exhibited a CTL response and after the second challenge, one of four newly infected macaques acquired a CTL response. The five animals with a CTL activity against SIVMAC proteins were protected from severe thrombocytopenia, which appeared in the five CTL-negative animals after infection. Our data show the induction of proliferative T cells by immunization with soluble SIVMAC antigen. This T cell reactivity was found in all animals protected from the first virus challenge, but did not confer protection from the second challenge. Interestingly, the proliferative T cell reactivity disappeared 2 weeks after virus infection. Furthermore a CTL response against viral proteins seems to protect infected animals from severe thrombocytopenia which is an early sign of AIDS in monkeys.

Animals↗
PubMed1991

Metabolic disorder as early consequence of simian immunodeficiency virus infection in rhesus macaques.

To establish whether the high plasma glutamate and low acid-soluble thiol (mainly cysteine) concentrations previously found in patients with HIV-1 infection are a consequence of the infection or a risk factor for its development, a closely related animal model, rhesus and fascicularis macaques infected with simian immunodeficiency virus (SIVmac251), was studied. The 23 infected macaques had significantly lower mean plasma thiol and higher glutamate concentrations than 18 uninfected controls (p less than 0.001). The changes were apparent by 1 week after infection. Thus, abnormal plasma glutamate and thiol concentrations are, at least in this model, a direct and early consequence of the retroviral infection.

Amino Acids↗
PubMed1991

Expression and frameshifting but extremely inefficient proteolytic processing of the HIV-1 gag and pol gene products in stably transfected rodent cell lines.

Expression, ribosomal frameshifting, and proteolytic processing of HIV-1 GAG and POL proteins were investigated in heterologous mammalian cells in order to elucidate the influence of the cellular background on these events. DNA fragments encoded by the gag and pol region were expressed in two rodent cell lines, LTK- and BHK. Both stably transfected cell lines continuously produce recombinant proteins which react with HIV-specific antisera. The GAG precursor and a 39-kDa proteolytic fragment thereof were the major recombinant proteins detected. Expression of the gag-pol region leads to the production of the GAG-POL precursor. Ribosomal frameshifting at the HIV-1 shifty sequence to a typical extent could be positively demonstrated by an enzyme assay. Despite the presence of the viral protease within the GAG-POL precursors, proteolytic processing of the HIV-derived polyproteins was extremely inefficient. The efficiency could not be enhanced by overexpression of the HIV-1 protease encoding region.

Animals↗
PubMed1991

Antibody response to the negative regulatory factor (nef) in experimentally infected macaques: correlation with viremia, disease progression, and seroconversion to structural viral proteins.

The antibody response to structural and regulatory viral proteins was studied in 14 rhesus (Macaca mulatta) and 6 cynomolgus (Macaca fascicularis) macaques experimentally infected with HIV-2 or SIVMAC. To investigate the humoral antibody response to the negative regulatory factor (nef), the recombinant protein was expressed to high levels with recombinant vaccinia virus (VV). nef-specific antibodies were detected in 14 of 20 infected macaques (70%). In sera of all infected monkeys antibodies directed to the structural proteins gp120, p56, and p24 appeared 2 to 6 weeks postinfection. In contrast, the extent and the appearance of nef-specific antibodies during the course of infection varied considerably between individual animals. However, only in sera of four animals (20%) were nef-specific antibodies detectable as early as those against the core proteins p24 and p56. In SIVMAC-infected rhesus macaques at different clinical stages, the antibody response towards nef neither correlated with the development of viral latency nor to disease progression or viremia. Our data indicate that in macaques experimentally infected with SIV or HIV-2 antibody formation against nef is not a useful diagnostic marker either for early detection of viral infection or of disease progression.

AIDS-Related Complex↗
PubMed1991

Structural comparison of the external glycoproteins of human and simian immunodeficiency virus.

The structural variability of the external glycoproteins of primate immunodeficiency viruses, has, so far, been investigated exclusively by sequence comparison of the respective proviral genomes. We have examined the structural relationship amount the external glycoproteins from three specific human immunodeficiency viruses (HIF-1, HIV-2), three specific simian immunodeficiency viruses from macaques (SIVmac) and three specific SIV from African green monkeys (SIVagm) by peptide mapping. Differences among glycoproteins were most pronounced between HIV-1 and SIVmac, as well as HIV-2. Two specific glycoproteins from independent SIVagm isolates were closely related to HIV-1, whereas the glycoprotein from a third SIVagm isolate was more similar to those of SIVmac and HIV-2. Our analysis reflects the classification of primate immunodeficiency viruses into three groups, the HIV-2 and SIVmac viruses, the green monkey isolates and HIV-1.

Amino Acid Sequence↗
PubMed1990

Partial purification and characterization of the reverse transcriptase of the simian immunodeficiency virus TYO-7 isolated from an African green monkey.

The reverse transcriptase (RT) was partially purified by a newly developed procedure from the simian immunodeficiency virus TYO-7 isolated from an African green monkey (SIVagmTYO-7). The method comprised lysis of the virus with nonionic detergent followed by two centrifugations in isopycnic sucrose density gradients and one velocity sedimentation in a glycerol gradient. The enzyme exhibited a purity of 70-80% and showed an exceptional high specific activity of 135 nmol incorporation of dTMP per milligram of protein in 1 h with poly(rA).oligo(dT) as template-primer (TP). The molecular weight of the native enzyme was estimated by velocity sedimentation analysis as 120K-130K. Investigation of the RT by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) showed that the active enzyme is a heterodimer composed of a 64- and a 50-kDa subunit. The two subunits were identified to be RT specific by Western blot analysis. In activity gels, both subunits exhibited enzymatic activity, whereby the 64-kDa subunit showed the predominant activity. The RT preferred the TP poly(rA).oligo(dT) over poly(rC).oligo(dG). With poly(rCm).oligo(dG), only marginal activity was detected, and no activity was measured with poly(dA).oligo(dT). The TP specificity was influenced by the reaction temperature. The highest activity was measured around the melting temperature of the TP used. Furthermore, the enzyme activity was more thermolabile when measured with poly(rA).oligo(dT) than with poly(rC).oligo(dG). To compare the specificity of RT inhibitors, their inhibition efficiency (IE) was defined as the ratio of the 50% inhibiting concentration (ID50) obtained with the RT in viral lysates to the ID50 of purified RT.

Animals↗
PubMed1990

Molecular cloning and characterization of a German HIV-1 isolate.

The genetic diversity of HIV-1 is well documented. Except for the HIV-1 isolate LAV-1BRU, no nucleic acid sequence of a European isolate of HIV-1 has been published to date. To further investigate the extent of the genetic variability and the evolution of HIV-1, we have isolated, cloned, and subsequently sequenced HIV-1 from a German patient with AIDS-related complex. Comparative studies of the nucleic acid sequence revealed that this isolate, designated HAN2, is highly divergent from the North American and African subtypes of HIV-1 and may represent a European subtype of HIV-1. Furthermore, a full-length molecular clone was derived from this isolate which was infectious in human T-cell lines. Therefore this new isolate will be particularly useful for studies on the genetic evolution and biology of HIV-1 as well as for testing antiviral substances and for developing vaccines.

Amino Acid Sequence↗
PubMed1990

Isolation and characterization of HIV-2ben obtained from a patient with predominantly neurological defects.

A HIV-2 strain named HIV-2ben was isolated from peripheral blood lymphocytes of a patient who, since 1984, had developed neurological symptoms such as Raynaud's syndrome, followed by paresthesia of extremities and ataxia, and finally paraparesis of the legs and incontinence. This new isolate could be distinguished from HIV-2rod by antibody-binding epitopes, peptide maps of core p24 and p18 polypeptides and restriction endonuclease cleavage pattern.

Animals↗
PubMed1990

Genomic divergence of an HIV-2 from a German AIDS patient probably infected in Mali.

The complete nucleotide sequence of an HIV-2 isolate derived from a German AIDS patient with predominantly neurological symptoms is reported. The HIV-2BEN sequence is highly divergent from those of previously described HIV-2 and SIV strains. Evolutionary tree analysis of eight HIV-2 sequences reveals the existence of three HIV-2 groups. HIV-2BEN belongs to a group with two isolates from Ghana and The Gambia. Based on a comparison of HIV-2BEN with six HIV-2 isolates, SIVsmm and SIVmac, the variability of the structural env and gag proteins is similar within the HIV-2/SIVsmm/mac and HIV-1 groups. In contrast, the regulatory HIV-1 proteins are more highly conserved than those from HIV-2 strains. Multiple sequence alignments reveal that some domains of the envelope and regulatory proteins are well conserved among HIV-1, HIV-2/SIVsmm/mac, SIVagm and SIVmnd. The identification of conserved domains within the external glycoprotein could help to develop broadly active vaccines.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Virus neutralizing and enhancing epitopes characterized by synthetic oligopeptides derived from the feline leukaemia virus glycoprotein sequence.

Synthetic peptides that mimic antigenic determinants of viral proteins were used in vaccine studies of feline leukaemia virus (FeLV) infection. Immunoreactive epitopes on FeLV gp70 and p15E were predicted according to the criteria of their terminal position, hydrophilicity and the probability of them constituting helical structures. Nineteen peptides, consisting of seven to 19 amino acid residues, were synthesized, of which two peptides were derived from the FeLV subtype A, 16 from subtype B and one from subtype C. Rabbits were immunized with individual peptides coupled to keyhole limpet haemocyanin and the specificity and biological activities of these hyperimmune sera were determined by ELISA, Western blotting, virus neutralization and cytotoxicity assays. All sera reacted specifically with the immunizing peptide. Twelve of the 19 peptides induced antibodies against purified gp85 and antibodies to 11 peptides reacted with the whole virus. One peptide representing the carboxy terminus of the transmembrane protein p15E, and two peptides derived from the external glycoprotein gp70 elicited neutralizing antibodies, whereas antisera against four peptides enhanced virus infection in vitro. None of the peptide antisera mediated complement lysis of FeLV-infected cells.

Amino Acid Sequence↗