concanavalin-a and Hepatitis--Viral--Animal

Chlordecone is an organochlorine used in the 1970's as a pesticide in banana plantations. It has a long half-life in the soil and can potentially contaminate humans and animals through food. Chlordecone targets, and mainly accumulates in, the liver, leading to hepatomegaly and neurological signs in mammals. Chlordecone does not cause liver injuries or any inflammation by itself at low doses, but it can potentiate the hepatotoxic effects of other chemicals and drugs. We studied the impact of chlordecone on the progression of acute hepatitis in mouse models of co-exposure to chlordecone with Concanavalin A or murine hepatitis virus type 3. We examined the progression of these two types of hepatitis by measuring hepatic transaminase levels in the serum and inflammatory cells in the liver, liver histological studies. Amplified tremors presented in the MHV3- chlordecone mouse model had led us to study the expression of specific genes in the brain. We show that chlordecone amplifies the auto-immune hepatitis induced by Concanavalin A by increasing the number of liver NKT cells, which are involved in liver damage. Chlordecone also accelerated the death of mice infected by murine hepatitis virus and enhanced the entry of the virus into the cervical spinal cord in infected mice, leading to considerable neurological damage. In conclusion, chlordecone potentiates both the Concanavalin A-induced hepatitis and brain damage caused by an hepatotropic/neurotropic virus.

Topics: Acute Disease; Animals; Brain; Chlordecone; Concanavalin A; Disease Models, Animal; Disease Progression; Hepatitis, Autoimmune; Hepatitis, Viral, Animal; Insecticides; Liver; Male; Mice, Inbred C57BL; Murine hepatitis virus; Necrosis

The current therapy for hepatitis B and C is based on systemic administration of recombinant human alpha interferon (r-hIFN-alpha). However, systemic delivery of r-hIFN-alpha is associated with severe side effects, but more importantly, it is effective in only a small percentage of patients. In an effort to maximize IFN-alpha antiviral efficacy, we have explored the therapeutic potential of murine IFN-alpha2 (mIFNalpha2) selectively expressed in the liver. To this end, we have developed a helper-dependent adenovirus vector (HD) containing the mIFN-alpha2 gene under the control of the liver-specific transthyretin promoter (HD-IFN). Comparison with a first-generation adenovirus carrying the same mIFN-alpha2 expression cassette indicates that at certain HD-IFN doses, induction of antiviral genes can be achieved in the absence of detectable circulating mIFN-alpha2. Challenge of injected mice with mouse hepatitis virus type 3 showed that HD-IFN provides high liver protection. Moreover, liver protection was also observed in acute nonviral liver inflammation hepatitis induced by concanavalin A at 1 month postinfection. These results hold promise for the development of a gene therapy treatment for chronic viral hepatitis based on liver-restricted expression of IFN-alpha2.

Topics: Adenoviridae; Animals; Chemical and Drug Induced Liver Injury; Concanavalin A; Female; Gene Expression; Genetic Therapy; Genetic Vectors; Helper Viruses; Hepatitis, Viral, Animal; Humans; Interferon-alpha; Liver; Mice; Mice, Inbred C57BL; Murine hepatitis virus

Natural infection by mouse hepatitis virus (MHV) can affect interpretation of immunological studies in mice. MHV, a collective term describing a group of corona viruses, is found in natural infections in over 70% of laboratory mouse populations in the U.S.A. and Canada. Natural outbreaks of MHV in our animal colony afforded us the opportunity to study MHV-induced immunosuppression as well as the effects of MHV infection on neurotransmitter immunomodulation. Concanavalin A (Con A)-stimulated DNA synthesis by spleen T lymphocytes from MHV-infected mice was 20-50% that of non-infected mice. The MHV infection also altered neurotransmitter modulation of spleen T-lymphocyte activation. In contrast to noradrenaline ablation of Con A-activated DNA synthesis by spleen lymphocytes from non-infected mice, DNA synthesis by the infected group was not inhibited by noradrenaline or dibutyryl-cAMP. These effects of MHV infection were specific for spleen T lymphocytes since MHV infection did not alter Con A stimulation of thymocytes, lipopolysaccharide stimulation of spleen B lymphocytes, or noradrenaline inhibition of thymocyte and B-cell DNA synthesis. MHV infection also did not alter spleen T-lymphocyte subset proportions. Thus, MHV infection inhibits spleen T-lymphocyte activation and blocks in vitro catecholamine and cAMP regulation of spleen T-cell activation but does not affect activation of thymic cells or spleen B cells.

Topics: Animals; Concanavalin A; DNA; Hepatitis, Viral, Animal; Immune Tolerance; Lymphocyte Activation; Male; Mice; Mice, Inbred BALB C; Norepinephrine; Spleen; T-Lymphocytes

Earlier studies revealed defective concanavalin A-stimulated proliferation and cytokine production by spleen cells derived from BALB/cByJ mice acutely infected with mouse hepatitis virus (MHV), strain JHM. Based on those observations, assays of in vitro antigen-presenting cell (APC) function were undertaken. APC function of unfractionated spleen cells from individual MHV-infected mice was highly variable. Experiments using pooled spleen cells derived from MHV-infected mice revealed that adherent spleen cell APC function was impaired to a much greater degree than B cell APC function. Adherent cells derived from peritoneal exudates of infected mice exhibited an APC defect that was similar in magnitude to that observed for splenic adherent cells. Splenic B cells derived from acutely infected BALB/cByJ mice harbored infectious MHV. In contrast, lysates of adherent spleen cells from acutely infected mice did not kill intracerebrally inoculated neonatal mice, but did induce seroconversion among all survivors. Despite impairment of APC function of cells derived from MHV-infected donors, neither indomethacin nor accessory cells from uninfected control mice restored concanavalin A-induced proliferative responses of spleen cells collected from acutely infected mice. These results and those of earlier studies suggest that, although APC function is impaired, in vitro T cell dysfunction exhibited by spleen cells from MHV-JHM-infected donors is probably related to an inherent proliferative defect subsequent to T cell activation. Defective concanavalin A-stimulated proliferation does not appear to be secondary to accessory cell function suppression or to inhibitory factors secreted by accessory cells.

Topics: Acute Disease; Animals; Antigen-Presenting Cells; Ascitic Fluid; B-Lymphocytes; Cell Separation; Cells, Cultured; Concanavalin A; Female; Hepatitis, Viral, Animal; Indomethacin; Lymphocyte Activation; Macrophages; Mice; Mice, Inbred BALB C; Mice, Inbred C3H; Mice, Inbred C57BL; Murine hepatitis virus; Spleen

Earlier studies from this laboratory showed that infection of BALB/cByJ mice by a natural route with mouse hepatitis virus, strain JHM (MHV-JHM), results in functional splenic T cell suppression in vitro. This was evidenced by reduced concanavalin A-driven spleen cell proliferation and interleukin (IL)2 production measured after conventional intervals of cell culture (72 and 24 h, respectively). The purpose of the present work was to determine whether MHV-induced T cell dysfunction is kinetic or absolute and whether production of other T-cell derived cytokines is defective. Bioassays revealed that production of IL2, gamma interferon, and IL4 by spleen cells from acutely infected mice is suppressed and that some of the defects are kinetic as well as absolute. Proliferative responses of both CD4+ and CD8+ T cells were depressed, but neither cell type contained infectious virus. Cells that proliferated poorly in response to concanavalin A were fully capable of responding to specific virus stimulation. These results further emphasize the potential complications that MHV infection may pose to immunologic research using mice.

Topics: Animals; CD4 Antigens; Cells, Cultured; Concanavalin A; Cytokines; Female; Hepatitis, Viral, Animal; Interferon-gamma; Interleukin-2; Interleukin-4; Lymphocyte Activation; Mice; Mice, Inbred BALB C; Murine hepatitis virus; Species Specificity; Spleen; T-Lymphocytes; T-Lymphocytes, Regulatory

Resistance of mice to mouse hepatitis virus type 3 (MHV3) infection is genetically determined. Normal adult A/J mice are resistant, and BALB/c mice are susceptible. Higher titers of virus and interferon (IFN) in vivo were found in MHV3-infected BALB/c mice compared with A/J mice. In vitro activation of macrophages (M phi) by lipopolysaccharide (LPS) delayed MHV3 replication only in cells that originated from A/J mice, although cell populations from both A/J and BALB/c mice were able to synthesize comparable amounts of IFN-alpha/beta. Using specific antibodies, we have shown that the delayed MHV3 replication in LPS-activated A/J M phi was due, in part, to IFN-alpha/beta. A/J M phi were found to be more sensitive to IFN-gamma than to IFN-alpha/beta, and BALB/c M phi did not develop an antiviral state to either IFN. Cultured spleen cells from A/J mice synthesized more IFN-gamma than BALB/c spleen cells after specific or non-specific stimulation. The results indicate that IFN-activated M phi may play a crucial role in the resistance to MHV3 infection. Since IFN-gamma is produced in large amounts by A/J spleen cells after specific stimulation with MHV3 and is efficient in activating the A/J M phi, a T cell-dependent mechanism is likely to be involved.

Topics: Animals; Antibodies, Viral; Cells, Cultured; Concanavalin A; Hepatitis, Viral, Animal; Immunity, Innate; Interferon-gamma; Lipopolysaccharides; Macrophage Activation; Macrophages; Mice; Mice, Inbred Strains; Murine hepatitis virus; Spleen; T-Lymphocytes

Peripheral blood lymphocytes (PBLs) isolated from woodchucks chronically infected with the woodchuck hepatitis virus (WHV) carry low levels of nonreplicating WHV DNA. When PBLs from chronic carrier woodchucks were activated in culture with the generalized mitogen lipopolysaccharide (LPS), WHV DNA replication was initiated in cells obtained from one of three animals examined. Intracellular WHV core particles, containing WHV DNA replication intermediates, RNA/DNA hybrid molecules, and an active endogenous DNA polymerase, appeared 3 days after the start of LPS stimulation. After 5 to 7 days of LPS stimulation, WHV DNA-containing particles, which displayed the properties of intact, mature virions, were released into the culture medium. These studies provide evidence for reactivation of a latent WHV infection of circulating lymphoid cells and indicate that the presence of nonreplicating hepadnaviral DNA in lymphoid cells represents a potentially active infection following cellular activation.

Topics: Animals; Cells, Cultured; Centrifugation, Density Gradient; Concanavalin A; DNA Replication; Ducks; Hepatitis B virus; Hepatitis Viruses; Hepatitis, Viral, Animal; Interleukin-2; Lipopolysaccharides; Lymphocyte Activation; Lymphocytes; Marmota; Mitogens; Nucleic Acid Hybridization; Phytohemagglutinins; Sciuridae; Virus Replication

Mouse hepatitis virus and Sendai virus are among the most common viruses naturally infecting laboratory mice. Concanavalin A-stimulated in vitro proliferative responses of splenocytes were examined after infection of BALB/cByJ mice with the JHM strain of mouse hepatitis virus (MHV-JHM) or Sendai virus. Mice were exposed to these viruses by presumed natural routes (per os or intranasally). Immunodepression was marked but transient among BALB/cByJ mice exposed to MHV-JHM. Among mice exposed to Sendai virus and examined over a 21-day period, spleen cells from only one mouse, sacrificed 10 days postinoculation, exhibited a severely impaired ability to respond to concanavalin A. Lymphokine production by spleen cells from control and infected mice was then assessed. IL 2 was either absent or present at very low levels in culture supernates of concanavalin A-unresponsive spleen cells from MHV-JHM-infected mice. Spleen cells from the single Sendai virus-infected mouse also produced very low levels of IL 2. In contrast, IL 1 was detected in supernatants of all spleen cell cultures derived from control, MHV-JHM-infected, or Sendai virus-infected mice. There was not a clear correlation between concanavalin A responsiveness and the ability of spleen cells to produce interferon-gamma. These results stress the importance of using laboratory mice of known microbiological status for immunologic experiments.

Topics: Animals; Concanavalin A; Female; Hepatitis, Viral, Animal; Interferons; Lymphocyte Activation; Lymphokines; Mice; Mice, Inbred BALB C; Murine hepatitis virus; Parainfluenza Virus 1, Human; Paramyxoviridae Infections; Spleen; T-Lymphocytes

Replication of MHV3 in macrophage-depleted T cells and effects of MHV3 infection on mouse lymphocytes were studied in mixed lymphocyte reaction and in mitogen-stimulated cells. In vitro infection of lymphocytes with infectious MHV3 resulted in replication of the virus and marked inhibition of the proliferative response of cells. In mixed lymphocyte cultures, a strong inhibition was obtained when either X-irradiated stimulator cells or responder cells were preinfected with infectious virus. Inactive virus was able, however, to induce a slight inhibition of MLC reaction following treatment of responder cells, but no inhibition was seen when stimulator cells were treated. Since the infection did not visibly affect lymphocyte viability, MHV3 appeared to replicate in lymphocytes without displaying any cytopathic effects comparable to those observed in infected macrophages.

Topics: Animals; Cell Division; Cells, Cultured; Concanavalin A; Hepatitis, Viral, Animal; Immune Tolerance; Lymphocytes; Macrophages; Mice; Mice, Inbred Strains; Murine hepatitis virus; T-Lymphocytes; Thymidine

We have investigated the changes in inducible suppressor activity in spleen cells of young BALB/c mice infected with A-59 strain of murine hepatitis virus. The peak histological and biochemical damage occurred four days after intraperitoneal inoculation of the virus. Before that, on day 2, there was a transient loss of suppressor activity inducible in splenic cells by in vitro incubation with the mitogen Con A. Sequential changes in the proliferative response of spleen cells to Con A also occurred, but did not account for the loss of inducible suppressor activity. This variation in activity of Con A-stimulated suppressor cells suggests an immunoregulatory role for these cells during experimental viral hepatitis.

Topics: Animals; Concanavalin A; Hepatitis, Viral, Animal; In Vitro Techniques; Lymphocyte Activation; Male; Mice; Mice, Inbred BALB C; Murine hepatitis virus; Spleen; T-Lymphocytes, Regulatory; Time Factors

Genetically resistant G3H mice routinely yielded macrophages that were resistant when grown in 90% horse serum. These mice also routinely yielded macrophages that were susceptible to the same virus, MHV (PRI), in vitro after the mice had been treated with three intraperitoneal doses, of hydrocortisone. Dexamethasone and prednisolone when similarly administered also increased the susceptibility of C3H macrophages taken from the treated animal, but progesterone and testosterone did not. In addition, spleen cells from mice treated with cortisone made the resistant C3H macrophages 100 times more susceptible in vitro. Increased in vitro susceptibility induced in this way by hydrocortisone was reversed by exposure to supernatant fluid removed from cultures of concanavalin A-treated spleen cells.

Topics: Animals; Cell Adhesion; Concanavalin A; Hepatitis, Viral, Animal; Hydrocortisone; Macrophages; Mice; Mice, Inbred C3H; Murine hepatitis virus; Spleen

By pretreatment with concanavalin A (Con A) both in vivo and in vitro genetically susceptible mice and their cultured macrophages have been converted to animals and cells which are phenotypically resistant to mouse hepatitus virus (MHV). Con A at 1.0 mg/mouse decreased the mortality from 100% to less than 40% by inducing a prominent inflammatory response, increasing the number of macrophages in the virus inoculation site, and producing a population of macrophages not uniformly susceptible to the virus. In addition, mediators derived from Con A-treated spleen cells conferred resistance to normally susceptible syngeneic macrophages to 100 TCID50 of MHV.

Topics: Animals; Cell Communication; Cells, Cultured; Concanavalin A; Hepatitis, Viral, Animal; Immunity; Lymphocyte Activation; Macrophages; Mice