Antiviral immunity

In this article, Rolf Zinkernagel and Hans Hengartner analyze unresolved aspects of antiviral immunity, particularly the nature of T-cell responses, the role of antigen and the establishment of immunological memory.     

Antiviral immunity in disseminated sclerosis

Titres of antibodies to various viral antigens, levels of immunoglobulins, and the rate of detection of specific IgM to measles virus were studied in the blood sera of 50 patients with multiple sclerosis and 50 normal subjects. High antibody titres to measles, mumps, rubella and parainfluenza type 3 virus antigens were revealed. Specific IgM to measles virus were detected in 50% of multiple sclerosis patients and in none of the normal subjects. The patients with multiple sclerosis showed no significant differences in the levels of immunoglobulins of the three main classes (G, A, M).     

Antiviral immunity and the role of dendritic cells

Using our experimental model we demonstrate the need for Th1 immune responses for recovery from influenza virus infection. Inoculation of IL-4 concurrent with infection significantly delays virus clearance and converts the immune response to a Th2 response. Immunization using live virus in the presence of IL-4 leads to generation of Th2 memory cells that fail to facilitate recovery upon subsequent virus infection. Inactivated virus expands Th2 cells, leading to responses similar to those observed following IL-4 infusion. Immunization using cultured dendritic cells incubated with live or inactivated virus mimics the results observed with direct virus injection. We demonstrate that in contrast to live virus-infected dendritic cells, inactivated virus fails to elicit Th1 immunity. This failure correlates with the inactivated viruses' inability to induce dendritic cell maturation. Thus, our data suggest that the polarity of the immune response is dictated by the nature of the antigen, and the trigger for influenza virus-induced DC maturation leading to Th1 immunity is dependent on virus replication.     

Aneuploidy patterns in drosophila melanogaster

By using an appropriate scheme, various combinations of losses and gains of chromosomes I and II arising in oocytes of Drosophila melanogaster were obtained. The frequencies of these combinations can be arranged as special sequences or patterns which we call “aneuploidy patterns.” Aneuploidy patterns were established for spontaneous, colchicine-induced, and X-ray=induced exceptions and were shown to be highly specific for the agent tested. Such patterns can be obtained very quickly, because only exceptional progeny survive. By establishing aneuploidy patterns for chemical agents one would get information on the “aneuploidizing” action of the compounds tested.     

Evidence for internuclear signaling in drosophila embryogenesis

Background : Syncytial nuclei in Drosophila embryos undergo their first 13 divisions nearly synchronously. In the last several cell cycles, these division events travel across the anterior–posterior axis of the syncytial blastoderm in a wave. The phenomenon is well documented but the underlying mechanisms are not yet understood. Results : We study timing and positional data obtained from in vivo imaging of Drosophila embryos. We determine the statistical properties of the distribution of division times within and across generations with the null hypothesis that timing of division events is an independent random variable for each nucleus. We also compare timing data with a model of Drosophila cell cycle regulation that does not include internuclear signaling, and to a universal model of phase‐dependent signaling to determine the probable form of internuclear signaling in the syncytial embryo. Conclusions : The statistical variance of division times is lower than one would expect from uncoordinated activity. In fact, the variance decreases between the 10th and 11th divisions, which demonstrates a contribution of internuclear signaling to the observed synchrony and division waves. Our comparison with a coupled oscillator model leads us to conclude that internuclear signaling must be of Response/Signaling type with a positive impulse. Developmental Dynamics 244:1014–1021, 2015. © 2015 Wiley Periodicals, Inc.     

Mushroom Bodies Enhance Initial Motor Activity in drosophila

Abstract: The central body (or central complex, CCX) and the mushroom bodies (MBs) are brain structures in most insect phyla that have been shown to influence aspects of locomotion. The CCX regulates motor coordination and enhances activity while MBs have, thus far, been shown to suppress motor activity levels measured over time intervals ranging from hours to weeks. In this report, we investigate MB involvement in motor behavior during the initial stages (15 minutes) of walking in Buridan's paradigm. We measured aspects of walking in flies that had MB lesions induced by mutations in six different genes and by chemical ablation. All tested flies were later examined histologically to assess MB neuroanatomy. Mutant strains with MB structural defects were generally less active in walking than wild-type flies. Most mutants in which MBs were also ablated with hydroxyurea (HU) showed additional activity decrements. Variation in measures of velocity and orientation to landmarks among wild-type and mutant flies was attributed to pleiotropy, rather than to MB lesions. We conclude that MBs upregulate activity during the initial stages of walking, but suppress activity thereafter. An MB influence on decision making has been shown in a wide range of complex behaviors. We suggest that MBs provide appropriate contextual information to motor output systems in the brain, indirectly fine tuning walking by modifying the quantity (i.e., activity) of behavior.     

Genotype and anesthetic determine mate choice in drosophila melanogaster

Genetic differences that influence mating preferences were studied in genetically defined lines ofDrosophila melanogaster. Initial results suggested substantial differences between two types of females with respect to the types of male preferred as mates, but further experimentation showed that the mating patterns were conditional on the mode of anethesia (CO₂ versus ether). In a statistical test of independence, the major determinant of mating choice in these experiments was due to an interaction effect between genotypes and mode of anesthesia. The observations might be explained by the differential sensitivity of male genotypes to ether. Etherization at emergence has lasting effects on mating behavior; it alters not only the latency and frequency of mating 4 days later, but also the pattern of matings observed.Research supported by a grant from the National Science Foundation (BSR 8211667) to J.W.C. We thank Drs. L. Heisler, K. Oberhauser, L. Patridge, and T. Tully for their critical comments.     

Antiviral Immunotherapy

Unselected intramuscular (IM) and intravenous (IV) immunoglobulins, as well as virus-specific hyperimmune globulins, occupy important roles as immunotherapy for viral infections. Standard IM immunoglobulins may be utilised in selected, susceptible patients for the prevention of hepatitis A and measles. Hyperimmune globulins to varicella zoster virus (VZV), hepatitis B virus and rabies have established indications for use as post-exposure prophylaxis. Cytomegalovirus (CMV) hyperimmune globulin has an indication for the prevention of primary CMV-associated disease in kidney transplantation and has been shown to decrease severe CMV-associated disease in liver transplantation. More recently, respiratory syncytial virus (RSV) hyperimmune globulin has been developed and is being utilised to prevent RSV disease in high risk infants and children during months of maximum risk for RSV infection. Unselected IV immunoglobulins (IVIg) have proven beneficial in preventing CMV-associated disease and graft-versus-host-disease in allogeneic bone marrow transplant recipients. In addition, IVIg plus ganciclovir is effective therapy for established CMV disease in both bone marrow and solid organ transplantation. IVIg for chronic anaemia associated with parvovirus B19 infection is gaining acceptance, as is the use of IVIg and intraventricular immunoglobulin for chronic meningoencephalitis associated with agammaglobulinaemia. Immunotherapy for the prevention or treatment of several other viral infections has been explored, but without clear conclusions. The use of human immunodeficiency virus (HIV) hyperimmune globulins in HIV-infected patients has yielded inconsistent results and the role of such therapy in the era of highly active antiretroviral therapy is uncertain. Oral immunoglobulins appear successful for rotaviral infections, but their exact use requires further clarification. Other immunotherapeutic modalities, such as monoclonal antibodies against CMV, RSV and HIV, have been developed but these agents have not undergone extensive clinical evaluation.     

The mutagenic effect of platinum compounds in drosophila melanogaster

The platinum compounds cis-platinum (II) diamminodichloride (cis-PDD) (an anti-tumor agent) and platinum tetrachloride (Pt Cl₄) induce a significant increase in recessive sex-linked lethal mutations in Drosophila melanogaster male germ cells in different developmental stages.     

Modafinil maintains waking in the fruit fly drosophila melanogaster

Fruit flies exhibit a sleep-like rest state that shares behavioral characteristics with mammalian sleep, including a homeostatic increase in rest after deprivation by mechanical methods. We tested the effect of modafinil, a novel wake-promoting agent, to discover whether its effect is conserved. Flies fed various concentrations of modafinil were compared to groups of control flies fed diluent only. Flies were also tested for a homeostatic response to the modafinil-related rest deprivation by examining rest and activity during recovery after 48H modafinil administration, compared to rest deprivation alone and to both treatments combined. The duration and consolidation of rest, and the duration, intensity, and circadian rhythms of activity were measured. Modafinil significantly and dose-dependently decreased rest when fed at concentrations from 2.5 mg/ml to 0.3125 mg/ml. Activity intensity was not increased, and circadian timing was unchanged, although the 2.5 mg/ml dose blunted the amplitude of overt circadian locomotor rhythms. Compared to controls, the duration of rest bouts was decreased in flies fed 2.5 mg/ml, and waking was frequently interrupted by 5-min periods of immobility. A rest rebound (significant increase in rest) followed withdrawal of either 2.5mg/ml or 0.625mg/ml modafinil after 48H. When directly compared to 6H total rest deprivation, the increase after withdrawal was briefer, reminiscent of the attenuated rest rebound seen in mammals, including humans, after modafinil. However, modafinil withdrawal combined with 6H total rest deprivation significantly enhanced the rebound, suggesting that a rest debt is accumulating during modafinil. We conclude that modafinil affects states of arousal in Drosophila in the same direction as it does in mammals. This discovery provides a tool for searching for conserved molecular mechanisms by which modafinil regulates rest and waking.     

Antiviral aptamers

Summary Aptamers are rare nucleic acid ligands, which can be concocted in the laboratory from the randomized pool of molecules by affinity and amplification processes. Aptamers have several properties as they can be applied complementarily to antibodies and have several advantages over antibodies. In the past, several aptamers have been selected with a view to develop antiviral agents for therapeutic applications. This review summarizes potent antiviral aptamers and their strategies to prevent the viral replication.     

Antiviral immunity and T-regulatory cell function are retained after selective alloreactive T-cell depletion in both the HLA-identical and HLA-mismatched settings.

Nonselective T-cell depletion reduces the incidence of severe graft-versus-host disease after allogeneic hematopoietic stem cell transplantation, but the cost is delayed and disordered antigen-specific immune reconstitution and increased infection. We use a method of selective depletion of alloreactive T cells expressing the activation marker CD69 after coculture with stimulator cells in a modified or standard mixed lymphocyte reaction. The technique has been shown to reduce alloreactivity while retaining third-party responses in vitro and, in a mismatched murine model, led to donor T-cell engraftment with a virtual absence of graft-versus-host disease and increased survival. We show in a human HLA-mismatched and unrelated HLA-identical setting that this technique retains >80% of specific cellular antiviral activity by cytomegalovirus-tetramer analysis and cytomegalovirus/Epstein-Barr virus peptide-stimulated interferon-gamma ELISpot assay. Furthermore, CD4(+) CD25(+) T-regulatory cells are not removed by this method of selective allodepletion and retain their function in suppressing allogeneic proliferative responses. Preservation of antiviral cytotoxic T lymphocytes in selectively allodepleted stem cell grafts would lead to improved antiviral immunity after transplantation. The retention of immunosuppressive CD4(+) CD25(+) T-regulatory cells could lead to more ordered immune reconstitution and further suppress alloreactive responses after transplantation.