Albrecht Werner

Productive infection of both CD4+ and CD4- human cell lines with HIV-1, HIV-2 and SIVagm.

Human monolayer cells of various origins were shown to be susceptible to infection by HIV-1, HIV-2 and simian immunodeficiency virus obtained from African green monkeys (SIVagm). Immunoperoxidase staining revealed infection of 2-7% of the monolayer cells, although in order to achieve infection approximately 50-fold more virus was necessary than with CD4(+)-permissive lymphoma cells. No CD4-receptor antigen expression by fibroblastoid cells was detectable by immunofluorescence using several monoclonal antibodies (MAbs), although a low level of CD4-specific messenger RNA expression was revealed by Northern analysis (with the exception of Tera-1 and RD cells). Attempts to block viral infection by anti-CD4 MAbs indicated a CD4 receptor-mediated mechanism for all lines tested except RD cells. We conclude that a low level of CD4-receptor expression is sufficient to allow infection of fibroblastoid cells. The infectability of a CD4-negative cell line indicates a second pathway of cellular infection, possibly mediated by a cellular receptor distinct from the CD4 molecule.

Molecular cloning and sequence analysis of interleukin 16 from nonhuman primates and from the mouse.

Abstract Interleukin 16 (IL-16) is synthesized as a 67 000 Mr precursor (pro-IL-16), but only a carboxy terminal part of 12 000–14 000 Mr is secreted by CD8(+) lymphocytes. This lymphokine binds to CD4 and has been shown to induce migration, affect the activation state of T cells, and inhibit immunodeficiency virus replication. It has been suggested that CD8(+) cell-derived soluble factors play a pivotal role in protecting natural-host nonhuman primates from developing immunodeficiency following SIV infection. In a first attempt to address this question, we cloned and sequenced the IL-16 cDNA from different primates. Here we report the pro-IL-16 sequence from chimpanzees, African green monkeys (AGM), rhesus macaques, and cynomolgus macaques. In order to compare and analyze structural motifs possibly involved in processing, intracellular targeting, or secretion, we extended our study to the New World monkeys saimiri and aotus and to the mouse. Alignments of deduced amino acids reveal that the human protein shares 99% similarity to that of chimpanzees, approximately 95% to rhesus, cynomolgus and AGM, about 90% to aotus and saimiri, and 77.5% to the mouse. Phylogenetic analyses revealed the expected evolutionary groupings.

Increased Serum and mRNA Levels of RANTES Associated with Elevated Levels of Activated CD8+CD38+ T Cells in HIV-1-Infected Individuals

The serum levels of the beta-chemokine RANTES and, albeit less, MIP-1 beta were found to be increased in 37 HIV-1 infected compared to seronegative individuals. In contrast the serum levels of IL-16 were only sporadically elevated in seropositives as well as in seronegatives. Concomitantly, the RANTES gene expression increased about tenfold in seropositives, whereas the MIP-1 beta and IL-16 mRNA levels were not elevated. No correlation between the increase of the MIP-1 beta and RANTES serum concentrations and the plasma virus load, the number of the peripheral CD4+ T cells or the therapy status of the patients was found. However, the increased proportion of activated CD8+CD38+ T cells in the peripheral blood of all seropositives paralleled the increased RANTES serum levels detected indicating that immune activation in HIV-1-infected individuals may contribute to increased RANTES serum levels.

Unexpected Coreceptor Usage of Primary Human Immunodeficiency Virus Type 1 Isolates from Viremic Patients under Highly Active Antiretroviral Therapy

Recently, combinations of antiretroviral drugs (highly active antiretroviral therapy [HAART]) have led to a dramatic reduction of human immunodeficiency virus type 1 (HIV-1)-related clinical symptoms. Success of treatment is defined as almost complete suppression of plasma viremia, although in a sizable fraction of patients this goal is not achieved. We characterized primary HIV-1 isolates from 2 cohorts of patients in which HAART failed in terms of viral suppression. One cohort showed clinical benefit and stable or increasing CD4+ T cell numbers despite high viral load. The second viremic cohort had no CD4+ T cell recovery and exhibited typical AIDS-related symptoms. Primary isolates from HAART patients with minor clinical symptoms used CXCR4 as the most relevant receptor on primary cells. Thus, for the first time, it is shown that patients improving clinically under HAART harbor relatively high viral loads with viruses preferring CXCR4 as coreceptor.

Decreased HIV diversity after allogeneic stem cell transplantation of an HIV-1 infected patient: a case report

The human immunodeficiency virus type 1 (HIV-1) coreceptor use and viral evolution were analyzed in blood samples from an HIV-1 infected patient undergoing allogeneic stem cell transplantation (SCT). Coreceptor use was predicted in silico from sequence data obtained from the third variable loop region of the viral envelope gene with two software tools. Viral diversity and evolution was evaluated on the same samples by Bayesian inference and maximum likelihood methods. In addition, phenotypic analysis was done by comparison of viral growth in peripheral blood mononuclear cells and in a CCR5 (R5)-deficient T-cell line which was controlled by a reporter assay confirming viral tropism. In silico coreceptor predictions did not match experimental determinations that showed a consistent R5 tropism. Anti-HIV directed antibodies could be detected before and after the SCT. These preexisting antibodies did not prevent viral rebound after the interruption of antiretroviral therapy during the SCT. Eventually, transplantation and readministration of anti-retroviral drugs lead to sustained increase in CD4 counts and decreased viral load to undetectable levels. Unexpectedly, viral diversity decreased after successful SCT. Our data evidence that only R5-tropic virus was found in the patient before and after transplantation. Therefore, blocking CCR5 receptor during stem cell transplantation might have had beneficial effects and this might apply to more patients undergoing allogeneic stem cell transplantation. Furthermore, we revealed a scenario of HIV-1 dynamic different from the commonly described ones. Analysis of viral evolution shows the decrease of viral diversity even during episodes with bursts in viral load.

Interleukin-16 serum levels during the course of HIV-1 infection

Objective. The CD8+ T cell derived cytokine interleukin-16 (IL-16) is chemotactic for CD4+ T cells and induces functional IL-2 receptors in CD4+ T cells. Since it has been shown that IL-16 can interfere with HIV-replication, it is important to investigate any reciprocal relationship between the progression stages of HIV-infection and corresponding IL-16 concentrations in the serum of these patients. Methods. 11 HIV-negative and 31 HIV-positive patients assigned to all CDC stages were selected randomly. From this study population, IL-16 serum concentrations and viral loads were determined. Statistical analyses of the correlation between IL-16 serum levels, viral load and CDC classification of the cohort were performed. Results. HIV-negative patients had significantly lower IL-16 serum levels than HIV positive patients. IL-16 levels rose with the onset of clinical symptoms. Within the group of HIV-positive patients, serum levels of IL-16 correlated to the CDC stage of the respective patients: During CDC stages A2 and B1 the concentration of IL-16 increased with a peak at stage B2, and decreased during stages B3, C2 and C3. In addition, IL-16 serum concentrations were significantly higher in HIV-positive non viremic patients than in viremic patients. Conclusions. IL-16 serum levels reflected for yet unknown reasons the immunological and clinical state of patients, and corresponded significantly to respective CDC stages. Evidence was found that IL-16 levels increase in response to the HIV-infection. IL-16 serum levels were significantly increased and dependent on the time of the first diagnosis in non viremic patients.

Chemoattractant Factors and the Control of Human Immunodeficiency Virus Replication

Factors secreted by CD8(+) T cells have been described to suppress immunodeficiency virus replication. The research efforts to identify these factors led to the proposal of some candidate proteins as being responsible for the antiviral effects. Chemokines and IL-16 are secreted by CD8(+) T cells and inhibit HIV replication through different mechanisms. However, their antiviral properties cannot fully explain the inhibitory activities found in cell culture supernatants from CD8(+) T cells.

HIV-Infektion als Beispiel einer erworbenen Immunmangelerkrankung

In diesem Kapitel werden erworbene Immunmangelerkrankungen beschrieben. Diese Erkrankungen mussen von den an anderer Stelle beschriebenen angeborenen (primaren) Immundefekten abgegrenzt werden. Den primaren Immundefekten werden in der Literatur oftmals die sekundaren Immunmangelerkrankungen gegenubergestellt. In diesem Sinn sind alle sekundaren Immunmangelerkrankungen erworben. Da aber bei den verschiedensten Erkrankungen erworbene Immunmangelsyndrome auftreten konnen (Tabelle 1.1.1), soll an dieser Stelle von dem im angelsachsischen Sprachgebrauch ublichen Verstandnis von „acquired immunodeficiency“ als einer von dem humanen Immundefizienzvirus (HIV) primar und ursachlich ausgelosten Erkrankung des Immunsystems beispielhaft die Rede sein.

HIV: Virologie und Impfungen

Die kausale Therapie viraler Erkrankungen ist trotz unbestreitbarer Erfolge in einigen Teilbereichen nach wie vor sehr schwierig. Dagegen last sich an zahlreichen Beispielen zeigen, das die Einfuhrung von Schutzimpfungen zu einem drastischen Ruckgang virusbedingter Epidemien gefuhrt und im Falle der Pocken sogar die Ausrottung des Erregers ermoglicht hat. Es uberrascht daher nicht, das schon sehr bald nach der eindeutigen Identifizierung eines Retrovirus als Ursache der erworbenen Immunschwache AIDS zahlreiche Gruppen mit der Entwicklung eines Impfstoffes begonnen haben. In den vergangenen zwolf Monaten konnte daher eine Reihe von potentiellen Vakzinen in Schimpansen getestet werden. Das enttauschende Ergebnis all dieser Versuche ist aber, das keines der geimpften Tiere gegen eine Infektion mit dem AIDS-Erreger HIV (Humanes Immundefizienz-Virus) geschutzt war. Die moglichen Ursachen fur diese Miserfolge und die moglichen Auswege aus diesem Dilemma werden in den folgenden Ausfuhrungen diskutiert.