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Biomedical subjects

G Hunsmann

Publications and source records attributed to G Hunsmann.

At least 127 records · Page 7Linked to original sources
PubMed1993

Protection of monkeys by a split vaccine against SIVmac depends upon biological properties of the challenge virus.

OBJECTIVE: To investigate the role of the anti-cellular immune response in the protection of rhesus macaques against infection with the simian immunodeficiency virus SIVmac. To determine the biological differences between SIV challenge stocks grown either on human T-cell lines or on monkey peripheral blood mononuclear cells (MPBMC). DESIGN: A protective SIVmac split vaccine was administered to rhesus macaques and their anti-, B- and T-cell response monitored. Vaccinees and controls were challenged with SIVmac grown either on human or on monkey cells. The in vivo replication rate of, and the immune response to, the two viruses was compared. METHODS: Five rhesus macaques were immunized with a total of 2 mg each of purified SIVmac251/32H grown on the human C8166 T-cell line. The antibody and proliferative T-cell responses were evaluated by enzyme-linked immunosorbent assay and T-cell proliferation assay, respectively. Four protected animals and four controls were reboosted and challenged with MPBMC-grown SIVmac251 (SIVmac251/MPBMC). Cell-free virus load was determined by titration of plasma for SIV infectivity on C8166 cells and antigen with a core antigen capture assay. RESULTS: Protection from virus challenge with C8166-grown SIVmac251/32H or SIVmac251/MPBMC did not correlate with anti-cellular antibodies or proliferative T-cell reactivities. Control animals infected with SIVmac251/MPBMC showed high persistent antigenaemia and high plasma virus titres. Both were absent in controls infected with complement C8166-grown SIVmac251/32H. Whereas the latter always seroconverted against the full panel of viral polypeptides, SIVmac251/MPBMC-infected animals showed a drastically decreased antibody response. CONCLUSIONS: Neither the antibody nor the proliferative T-cell response to SIVmac correlates with protection from virus challenge. In contrast to SIVmac251/32H grown on C8166 cells, the MPBMC-grown challenge virus SIVmac251 appears to belong to the 'rapid-high' phenotype, possibly explaining the lack of protection against this SIV.

Animals↗
PubMed1993

Differences in the B and T cell immune response to the envelope glycoprotein 130 (gp130) of the macaque strain of simian immunodeficiency virus (SIVmac), induced by immunization of rhesus macaques with virus-derived or vaccinia virus-expressed gp130.

Rhesus macaques were immunized with purified virus-derived simian immunodeficiency virus of macaques (SIVmac) 251/32H glycoprotein 130 (gp130) or primed with recombinant vaccinia virus (VV) expressing the env gene of the SIVmac BK28 clone and boosted subsequently with virus-derived gp130. High antibody titres of at least 10(4) against recombinant gp140 were induced with both vaccines. Analysis of the antibody specificity with a peptide ELISA revealed that different linear epitopes were recognized after administration of virus-derived gp130 compared with those after priming with VV. Antibodies to some epitopes (peptides 10 and 49), which were also found in SIV-infected animals, were induced with both vaccines, whereas antibodies to other regions were induced by only one vaccine preparation. The analysis of the helper T cell response revealed a poor immunogenicity of the virus-derived gp130, whereas priming with VV induced a considerable helper T cell activity in all three vaccinees after the second VV infection. Using synthetic peptides, several epitopes were identified. Our observations show that immunization with a virus-derived gp130 or live recombinant VV induces a considerably different antibody and helper T cell response. These differences in immunogenicity might have important implications for further vaccine development.

Amino Acid Sequence↗
PubMed1993

Importance of vpr for infection of rhesus monkeys with simian immunodeficiency virus.

The importance of the vpr gene for simian immunodeficiency virus (SIV) replication, persistence, and disease progression was examined by using the infectious pathogenic molecular clone called SIVmac239. The ATG start codon of the vpr gene was converted to TTG by site-specific mutagenesis. The constructed Vpr- mutant virus is identical with the parental SIVmac239/nef-stop virus with the exception of this one nucleotide. These viruses replicated with similar kinetics and to similar extents in rhesus monkey lymphocyte cultures and in the human CEMX174 cell line. Five rhesus monkeys were inoculated with the Vpr- variant of SIVmac239/nef-stop, and two monkeys received SIVmac239/nef-stop as controls. Both controls showed reversion of the TAA stop signal in nef by 2 weeks postinfection, as has been observed previously. Reversion of the TAA stop codon in nef also occurred in the five monkeys that received the Vpr- variant, but reversion was delayed on average to about 4 weeks. Thus, the mutation in vpr appeared to delay the rapidity with which reversion occurred in the nef gene. Reversion of the TTG sequence in vpr to ATG was observed in three of the five test animals. Reversion in vpr was first observed in these three animals 4 to 8 weeks postinfection. No vpr revertants were found over the entire 66 weeks of observation in the other two test animals that received the vpr mutant. Antibodies to vpr developed in those three animals in which reversion of vpr was documented, but antibodies to vpr were not observed in the two animals in which reversion of vpr was not detected. Antibody responses to gag and to whole virus antigens were of similar strength in all seven animals. Both control animals and two of the test animals in which vpr reverted maintained high virus loads and developed progressive disease. Low virus burden and no disease have been observed in the two animals in which vpr did not revert and in the one animal in which vpr reversion was first detected only at 8 weeks. The reversion of vpr in three of the five test animals indicates that there is significant selective pressure for functional forms of vpr in vivo. Furthermore, the results suggest that both vpr and nef are important for maximal SIV replication and persistence in vivo and for disease progression.

Amino Acid Sequence↗
PubMed1993

Characterization of monoclonal antibodies to the envelope proteins of an immunodeficiency virus of African green monkeys, SIVagmTYO-7.

Five monoclonal antibodies (mabs) specific for the envelope proteins of a simian immunodeficiency virus of African green monkeys (SIVagm) have been raised. Two mabs were directed against distinct epitopes on the transmembrane protein gp41. A conformational epitope on the gp130 was recognized by three mabs. This is the first report on mabs specific for SIVagm-gp130. Studies of the cross-reactivities revealed that the epitopes recognized by the env-directed mabs are conserved species-specifically in SIVagm isolates. Therefore, these mabs can be used to distinguish SIVagm strains from other virus groups.

Animals↗
PubMed1993

Cellular immune response to SIVmac and HIV-2 in macaques: model for the human HIV-1 infection.

SIV and HIV-2 infection of macaques has become a widely used model to study human HIV infection because the pathogenicity of, as well as the immune responses to, the viruses can be examined conveniently. In particular, the cellular immune responses to SIV or HIV-2 have been investigated thoroughly. This review summarizes the knowledge about helper and cytotoxic T-cell immunity in macaques, and it discusses the relevance and applications of this primate animal model for AIDS research.

Animals↗
PubMed1993

[Post infection antiidiotype vaccination against HIV: results of a phase Ia pilot study].

The mAb IOT4A against the HIV-gp 120 binding site on CD4 was shown to elicit the production of specific anti-idiotypes in rabbits neutralising HIV-1 in vitro. This study was designed in order to determine the safety and efficacy of the mAb IOT4A for the immunization of HIV+ volunteers. 10 patients in stages WR2-WR4B of HIV-disease were given six s.c. injections of the mAb IOT4A as an alum precipitate (each 3 patients receiving 0.6 or 1.2 mg, 4 patients receiving 2.4 mg). 6 patients subsequently received a booster immunization with the same dose of the mAb IOT4A. The immunization schedule was accompanied by monitoring clinical, immunologic and virologic parameters. No systemic toxic or allergic effects of the idiotype vaccine were observed. 8/10 vaccinees displayed a delayed-type hypersensitivity at the location of antibody administration beyond the third injection. The relative and absolute CD4 count showed a sustained increase in 8/10 patients at the end of the booster immunization and an additional raise after booster immunization in 6/6 patients. 624 antigen levels became negative in 2/2 patients during vaccination. In 4/10 patients in increase in HIV/gp 120 antigen binding titres was observed. HIV neutralisation titer remained stable throughout the observation period, and no progression in HIV disease was observed in all patients included in this study. The administration of the mAb IOT4A as a vaccine in HIV-infected volunteers was well tolerated. The mAb ITO4A induced the production of specific anti-idiotypes, that might have been of clinical benefit.(ABSTRACT TRUNCATED AT 250 WORDS)

Antibodies, Anti-Idiotypic↗
PubMed1993

Alterations of thymus cortical epithelium and interdigitating dendritic cells but no increase of thymocyte cell death in the early course of simian immunodeficiency virus infection.

The role of the thymus in the pathogenesis of simian acquired immunodeficiency syndrome was investigated in 18 juvenile rhesus monkeys (Macaca mulatta). The thymus was infected from the first week post-SIVmac inoculation, but the amount of virus-positive cells was very low (< 1 in 10(4) T cells) as demonstrated by polymerase chain reaction and in situ hybridization. First morphological alteration was a narrowing of the cortex at 12 and 24 wpi. Morphometry revealed no increase of pyknotic T cells but a decrease of the proliferation rate and flow cytometry showed a reduction of the immature CD4+/CD8+ double-positive T cells. Ultrastructural analysis revealed vacuolization, shrinkage, and finally cytolysis of the cortical epithelial cells and the interdigitating dendritic cells. Immunofluorescence staining exhibited a widespread loss of cortical epithelial cells. This damage to the thymic microenvironment could explain the breakdown of the intrathymic T cell proliferation. It preceded fully developed simian acquired immunodeficiency syndrome and is therefore considered to play a major role in its pathogenesis.

Animals↗
PubMed1992

Neutralization of HIV-1 by anti-idiotypes to monoclonal anti-CD4. Potential for idiotype immunization against HIV.

Anti-idiotypic antibodies were raised in rabbits against a panel of 11 murine mAb directed to the human CD4 receptor. Selection of mAb for vaccination was based on inhibition studies demonstrating that these mAb recognized CD4/V1 epitopes implicated in HIV-1-gp120 binding. Purified antisera showed high titer anti-Id activity and reacted specifically with Ag-combining site-related Id of the mAb used for their generation. Anti-Id either detected a private Id of the immunizing mAb or displayed a partial cross-reactivity with Id of other mAb to CD4. Eight anti-Id to six different mAb were shown to recognize determinants of recombinant HIV-1-gp120 or of HIV-1-gp160 as shown by ELISA and radioimmunoprecipitation assay. These anti-Id were capable of inhibiting HIV infection up to 100% in a MT-4 cell assay in vitro. In addition to neutralizing infectivity of cell-free virus, anti-Id to two mAb--the mAb IOT4a and 7.3F11--were also shown to inhibit HIV-induced syncytia formation up to 100%. Anti-Id to the mAb IOT4a, 7.3F11, and to the mAb anti-Leu3a interfered with rgp120 binding to cellular CD4 as assessed by flow cytometry. These results demonstrated that mAb specific for both CDR2- and CDR3-like regions of CD4 were capable of inducing HIV-1-gp120 cross-reacting anti-Id neutralizing HIV-1 in vitro. These studies may have implications for the development of a gp120 internal image based vaccine against HIV.

Animals↗
PubMed1992

Detection of viral surface antigens on HIV-2ben infected human tumor cell lines by flow cytometry.

The human monocytic cell line U-937 clone 2 and two T-cell lines CEM and MOLT-4 clone 8 were infected with HIV-2ben, a recent isolate of HIV-2. Infection and subsequent antigen expression on the cell surface was monitored by flow cytometry using a rabbit-anti-serum against tween-ether-treated HIV-2ben and a fluorescein-isothiocyanate-conjugated IgG against rabbit-IgG. The sensitivity of the three cell lines to infection with HIV-2ben correlated with the percentages of CD4-expressing cells but not with the levels of CD4-expression on the cell. The appearance of viral surface antigens preceded the formation of syncytia and correlated closely with the infecting virus dose. After 1-2 weeks in culture, 20-85% of the cells of each line expressed viral surface antigens. The variation depended on the cell type and cell culture conditions. The MOLT-4 clone 8 and the U-937 clone 2 cells died around 10 or 20 days, respectively, after HIV-2ben infection. Only HIV-2ben infected CEM cells grew permanently. Flow cytometry was an appropriate method to monitor the expression of viral proteins on the cell surface of HIV-infected cell lines. Flow cytometry proved to be more sensitive than determination of RT activity in supernatants of HIV-infected cells and more precise than light microscopy examinations.

Antigens, Surface↗
PubMed1992

Differential diagnosis of HTLV-I-associated myelopathy and multiple sclerosis in Iranian patients.

Two Iranian patients with chronic progressive spastic paraparesis and urinary dysfunction were referred to our hospital with the presumptive diagnosis of multiple sclerosis (MS). Routine CSF analysis and magnetic resonance imaging of the two patients were only partially characteristic of MS. Testing for antibodies to human T-cell leukemia virus type I [HTLV-I] in serum using a radioimmune precipitation assay revealed antibodies to HTLV-I in both patients. The infection with HTLV-I was confirmed by polymerase chain reaction (PCR) and liquid hybridization analysis using primers to the tax/rex region and a corresponding probe, demonstrating proviral DNA in peripheral blood mononuclear cells of both patients. On the basis of these findings demonstrating the presence of proviral HTLV-I DNA in the two Iranian patients, the initial diagnosis of MS was corrected to that of HTLV-I-associated myelopathy (HAM). In contrast, several patients with definite MS (nine from Germany, two from Iran) with a relapsing and remitting form of the disease were tested for HTLV-I infection by enzyme-linked immunosorbent assay and PCR, which yielded negative results. However, the mother of one HAM patient was found to be infected with HTLV-I. To support an association between HTLV-I infection and CNS disease in the two HAM patients, we analyzed the production of specific IgG antibodies within the CNS based on a simple enzyme immunoassay for viral IgG antibodies in CSF and serum. In the two HAM patients there was significant intrathecal antibody production directed against HTLV-I, but this was not found in any of the samples from MS patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Deltaretrovirus Antibodies↗
PubMed1992

Immunization with tween-ether-treated SIV adsorbed onto aluminum hydroxide protects monkeys against experimental SIV infection.

In order to examine the efficiency of an AIDS vaccine potentially acceptable for human use we have investigated a split vaccine. Since such vaccines are safe and efficient, they have been in use for many years to protect man against enveloped RNA viruses, e.g., influenza and measles. Seven rhesus monkeys were immunized at Week 0, 4, 8, and 16 by im injection of 2 ml of vaccine containing 140 micrograms of Tween-ether-disrupted SIVmac251/32H adsorbed onto aluminum hydroxide. The immunized animals and three nonvaccinated control monkeys were challenged 2 weeks after the last immunization by iv injection of 10 to 50 minimal monkey infectious doses of SIVmac251/32H. Four of seven immunized animals did not show any signs of virus replication and therefore appeared to be protected. Nonvaccinated control animals and the vaccine failures showed a rise in their urinary neopterin concentrations 1 to 2 weeks after infection. At the end of the second week and thereafter, cocultures and polymerase chain reaction of their peripheral blood lymphocytes were positive. After the challenge, control animals and infected vaccinees showed a primary or secondary antibody response while antibody titers declined in virus-negative animals. Specific cytotoxic T-lymphocytes were not present prior to challenge, but were present in some animals thereafter. Therefore, these seem to reflect a response to viral replication rather than to immunization. Prior to challenge the CD4-positive lymphocytes of the peripheral blood of the four virus-negative animals only proliferated after exposure to the immunizing antigen. Thus, this reaction appears to predict protection.

Adjuvants, Immunologic↗
PubMed1992

Isolation and characterization of a retrovirus from the fish genus Xiphophorus.

A cell line (BsT) established from neoplastic embryonal tissues of the platyfish (Xiphophorus maculatus) released spontaneously retrovirus-like particles. The particles have a buoyant density of 1.16 g/ml, a mean diameter of 100 nm and the morphology of immature retroviruses. The particle-associated proteins p70, p65, and p28 react with an antiserum directed against the major internal feline leukemia virus structural protein p27. The particles are associated with a reverse transcriptase. The purified enzyme has a molecular weight of about 70 kDa and prefers the template primers poly(rA):oligo(dT), poly(dC):oligo(dG), and poly(rC):oligo(dG) in the presence of Mn2+. The enzyme activity is inhibited by antibodies directed against the reverse transcriptase of feline leukemia virus and simian sarcoma virus. The particles contain a ribonucleic acid of about 70 S. In an endogenous reverse transcriptase reaction nucleic acids in the range of 0.2 to 0.4 kb were synthesized. In Northern blots with these nucleic acids as probe, three transcripts of about 8.5, 4.2, and 1.5 kb were detected in BsT cells. Southern blot analysis with the same probe demonstrates related sequences in the DNA of BsT cells and the platyfish and swordtail (Xiphophorus helleri). Hybridization experiments with the LTR-gag region of the feline leukemia virus show homologous sequences in the Xiphophorus genome.

Animals↗
PubMed1992

Generation of macaque B lymphoblastoid cell lines with simian Epstein-Barr-like viruses: transformation procedure, characterization of the cell lines and occurrence of simian foamy virus.

Two simian Epstein-Barr-like viruses, a rhesus Epstein-Barr virus and Herpesvirus papio, were used to transform B cells from rhesus or cynomolgus macaques. The resulting cell lines exhibited predominantly a B lymphocyte phenotype and expressed Epstein-Barr virus antigens. The majority of B lymphoblastoid cell lines from macaques, which were seropositive for simian foamy virus, developed giant cells in culture. The cytopathic agent was identified as a foamy virus and was transmissible to human embryonal fibroblasts. Treatment of cell cultures with AZT abolished giant cell formation.

Animals↗
PubMed1992

Morphogenesis of recombinant HIV-2 gag core particles.

The gag-pol coding region of the HIV-2BEN genome was expressed in CV-1 cells infected with four recombinant vaccinia viruses (VV). These recombinant VV encoded either the whole gag-pol region or the gag gene including the protease-coding region of the pol gene or the gag gene truncated at its 3'-end or only the pol gene. The HIV-2BEN gag precursor p55, its mature cleavage products p24 and p17 as well as the pol reverse transcriptase (RT) p66 were detected in VV-infected CV-1 cells. The p55 and two intermediate cleavage products p40 and p35 were myristilated. Comparison to lysates of permanently HIV-2BEN-infected Molt 4 clone 8 cells revealed that several additional gag and pol proteins were present in the VV-infected CV-1 cells. Deletion of the gag and pol overlapping region coding for the viral protease prevented cleavage of the recombinant gag precursor. Electron microscopy of VV-infected CV-1 cells revealed budding structures and immature as well as mature retroviral particles formed by the recombinant gag proteins. Striking differences in the ability to form complete particles were observed between the different recombinant VV. Expression of the truncated gag gene led to the formation of budding structures, but completely budded circular particles were not detectable. Such particles were produced by expression of the whole gag gene and the protease. Mature virions with an internal core structure were only detected in VVgagpol-infected cells. From these findings we conclude that the 3'-end of the gag gene coding for the p16 protein is essential for the formation of complete HIV-2 particles and that the pol proteins support the assembly of the viral core.

Base Sequence↗
PubMed1992

Characterization of the endogenous reverse transcriptase reaction products of SIVagmTYO-7, a simian immunodeficiency virus isolated from an African green monkey.

The products of the endogenous reverse transcriptase reaction of SIVagmTYO-7 were characterized after the reaction conditions had been optimized. The major reaction product in the presence of actinomycin D and oligo(dT) was a DNA with a size of 300 bases. Without actinomycin D two additional reaction products with 600 or 700 bases appeared. The 300 base product was identified as the (-)strong-stop DNA, whereas the 700 base product is the (+)strong-stop DNA. The 600 base product appeared only after oligo(dT) priming. The (-)strong-stop DNA hybridized specifically with a 9 kb RNA found in virus particles and three RNA species of 1.8, 4.8 and 9 kb isolated from SIVagmTYO-7 infected cells.

Animals↗
PubMed1992

Human retroviruses.

It was only in 1980 that the first human retrovirus, HTLV-1, was isolated. Since then, HTLV-2, HIV-1 and HIV-2 have been identified. All four viruses are transmitted with varying efficiency sexually, vertically from mother to infant, and through blood by transfusion or contamination. HTLV-1 is endemic in populations in south-west Japan, Taiwan, sub-Saharan Africa, the Caribbean, southern USA, central and south America, Australia, Papua New Guinea, Solomon Islands and western Asia. There is now epidemic spread amongst IVDUs in north and south America and southern Europe. HTLV-1 is the aetiological agent of adult T-cell leukaemia/lymphoma (ATL) and tropical spastic paraparesis/HTLV-1 associated myelopathy (TSP/HAM). Other associations which may be causative are with polymyositis, infective dermatitis, gastrointestinal malignant lymphoma and chronic lymphatic leukaemia. ATL appears to be due to malignant transformation of HTLV-1 infected cells, and TSP/HAM to chronic activation of these cells. The epidemiology of HTLV-2 is being separated only recently from HTLV-1 through the application of PCR. It has a low level of endemicity in populations of central Africa, and central and south America. It is being spread epidemically amongst IVDUs in north America and southern Europe. Its association with any pathology in man remains uncertain. HIV-1 is epidemic and spreading rapidly throughout the world. In areas where homosexual contact was the predominant mode of transmission, heterosexual spread is becoming increasingly important. The areas where heterosexual contact is the predominant mode of transmission include the worst affected populations in the world, for example sub-Saharan Africa and some of the Caribbean. There have been recent and explosive increases of HIV-1 seroprevalence in IVDUs and female prostitutes in Asia, especially Thailand and India. Of the diverse pathology following infection, only the haematological consequences are reviewed in detail: these include anaemia, leucopenia, thrombocytopenia, disorders of coagulation and lymphomas. HIV-2, compared to HIV-1, is less infectious and causes less immunosuppression with more slowly progressive disease. It is prevalent in west Africa, but is spreading, albeit slowly, far beyond.

Acquired Immunodeficiency Syndrome↗
PubMed1992

CD4-binding of gp130 micelles isolated from SIVagmTYO-7.

The binding and binding inhibition of the SIVagmTYO-7 external glycoprotein gp130 in micellar form to the CD4 molecule on human Molt-4 clone 8 cells was investigated. The best binding of gp130 to Molt-4 clone 8 cells occurred at pH 5.5 to 6.5 at 37 degrees C after 4 h or at room temperature after 10 h. The dissociation constant of this reaction was 0.2-0.4 nM, with both soluble CD4 or CD4 on Molt-4 clone 8 cells. This value is close to 0.15 nM determined for the antihuman CD4 monoclonal antibody 30F16H5. After partial deglycosylation of gp130, a 90 kD product arose which still bound to CD4. Fully deglycosylated gp130 of 60 kD was still immunoprecipitable, but had lost the CD4 binding activity. Lens culinaris agglutinin was able to inhibit the gp130-CD4 interaction very efficiently, while the agglutinin of Phaseolus vulgaris was half as efficient and Canavalia ensiformis was inefficient. CD4 binding of gp130 micelles was also inhibited with several anti CD4 monoclonal antibodies directed against the OKT4a epitope as well as with soluble recombinant CD4.

Antibodies, Monoclonal↗