Genetic and pharmacological manipulation of mu opioid receptors in mice reveals a differential effect on behavioral sensitization to cocaine

Cocaine-induced behavioral sensitization is a complex phenomenon involving a number of neuromodulator and neurotransmitter systems. To specifically investigate the role of the micro opioid receptor (MOR) in cocaine-induced behavioral sensitization in mice, both genetic and pharmacological approaches were undertaken. MOR-1 deficient mice of varying backgrounds (C57BL/6J, 129S6, F1 hybrid 129S6xC57BL/6J and 129S6xC57BL/6J) and wild-type C57BL/6J mice exposed continuously to naltrexone, an opioid receptor antagonist, received single daily injections of saline or cocaine for 10 days. All mice received a single cocaine challenge 7 days following the last saline or cocaine injection to test for the expression of sensitization. The locomotor-stimulating and sensitizing effects of cocaine observed in MOR-1 wild-type mice were absent in MOR-1 knockout mice maintained on the mixed 129S6xC57BL/6J background. In contrast, MOR-1 deficient mice developed on a C57BL/6J background showed an accentuated sensitivity to cocaine-induced locomotion. Cocaine's psychomotor activating effects were more pronounced in the MOR-1 C57BL/6J knockouts injected daily with cocaine than in the MOR-1 wild-type mice. Similar locomotor-stimulating and sensitizing effects were found in both F1 hybrid 129S6xC57BL/6J MOR-1 wild-type and MOR-1 knockout mice, while the 129S6 strain showed an overall indifference to cocaine. That is, both the locomotor-stimulating and sensitizing effects of cocaine were absent in both MOR-1 wild-type and MOR-1 knockout mice maintained on the 129S6 background. Lastly, the locomotor-stimulating and sensitizing effects of cocaine were attenuated in C57BL/6J wild-type mice exposed continuously to naltrexone. Collectively, these data support a role for opioidergic involvement in cocaine-influenced behavior in mice. Moreover, MORs appear to differentially modulate a sensitized response to cocaine in different strains of mice as delineated by MOR-1 gene deletion and pharmacological antagonism.     

Activation of natural killer cells and induction of interferon after injection of mouse hepatitis virus type 3 in mice.

High levels of natural killer (NK) cell activity and high titers of interferon were observed in the peritoneal exudate of C57BL/6 mice 20 to 50 h after injection of mouse hepatitis virus type 3 (MHV3) but not during the first 10 h after infection. C57BL/6 mice were susceptible to MHV3 infection and showed high titers of MHV3 in the peritoneal exudate 48 h after infection. A/J mice, in contrast, were resistant to the dose that killed 100% of the C57BL/6 mice (10 macrophage-infecting doses) and showed considerably lower virus titers than those shown by C57BL/6 mice. NK cell activity and interferon titers were significantly lower in the peritoneal exudate of A/J mice than in that of C57BL/6 mice. Serum interferon titers were also lower in A/J mice. Thus, our data show an inverse relationship between resistance and the levels of these two parameters. The data suggest that, in contrast to the situation observed with certain herpesviruses, interferon and NK cells may not be of overwhelming importance in the defense of mice against MHV3.     

Attenuation of lung inflammation and fibrosis in interferon-gamma-deficient mice after intratracheal bleomycin

Because mouse strains susceptible to bleomycin, such as C57BL/ 6J, tend to produce T helper type 1 (Th1) cytokines in response to immune activation, we hypothesized that the inflammatory response to bleomycin is mediated, in part, by local production of the Th1 cytokine interferon-gamma (IFN-gamma). Consistent with this hypothesis, fibrosis-prone C57BL/6J and A/J mice demonstrated significantly elevated expression of IFN-gamma protein (by enzyme-linked immunosorbent assay) in bronchoalveolar lavage fluid at 24 h, and subsequently increased lung inflammation, weight loss, and mortality 10 d after intratracheal bleomycin administration compared with fibrosis-resistant BALB/c mice or saline control mice. To directly determine a role for IFN-gamma in bleomycin toxicity, we exposed C57BL/6J mice with a homozygous null mutation of the IFN-gamma gene (IFN-gamma[-/-]) and wild-type C57BL/6J mice to intratracheal bleomycin. IFN-gamma(-/-) mice demonstrated significantly lower parenchymal inflammation, weight loss, and mortality 10 d after 5 U/kg intratracheal bleomycin administration compared with control mice. At 3 wk after 1.5 U/kg bleomycin exposure, single lung collagen determined by hydroxyproline assay was significantly lower in IFN-gamma(-/-) mice compared with wild-type C57BL/6J mice. Together, these results suggest that IFN-gamma mediates, in part, bleomycin-induced pulmonary inflammation and fibrosis.     

Relative susceptibilities of inbred mouse strains C57BL/6 and A/J to infection with Histoplasma capsulatum.

Differences in the 30-day survival of Histoplasma capsulatum after intravenous injection indicated that the A/J strain of inbred mouse was more resistant to experimental infection than was the C57BL/6 strain. CFU from the spleens of infected animals increased during the first week after injection but gradually declined over the next 3 weeks. The CFU per gram of tissue in the C57BL/6 animals were 10- to 100-fold higher than were those in the A/J mice during the time between 7 and 28 days after infection. The units of gamma interferon (IFN-gamma) in supernatants of spleen cells stimulated with heat-killed yeast cells of H. capsulatum reached a peak at the time of the largest number of CFU per gram of tissue. The titers of IFN-gamma at days 3 to 5 were higher in the A/J mice than they were in the C57BL/6 mice, but from days 7 to 28, the titers of IFN-gamma were not correlated with the more efficient clearance of the fungus from the spleens of A/J mice. The L3T4+ spleen cells were shown to be active IFN-gamma producers. Treatment of Histoplasma-infected mice with anti-IFN-gamma antibody resulted in much larger tissue burdens of the fungus in the lungs and spleens of treated animals than in untreated animals. There was no marked difference in the result of treatment with anti-IFN-gamma antibody between A/J and C57BL/6 mice. Treatment of Histoplasma-infected mice with recombinant murine IFN-gamma did not alter the course of infection in either inbred strain of mouse.     

Increase of γδ T Lymphocytes in Murine Lungs Occurs during Recovery from Pulmonary Infection by Nocardia asteroides

Previous studies have demonstrated that gammadelta T lymphocytes are important for host resistance to pulmonary infection of the murine lung by log-phase cells of Nocardia asteroides. To study the role of gammadelta T cells in nocardial interactions in the murine lung, C57BL/6J wild type and C57BL/6J-Tcrd (gammadelta T-cell knockout mice) were infected intranasally with log-phase cells of N. asteroides GUH-2. At 3, 5, and 7 days after infection, the gammadelta T cells were quantified by multiparameter flow cytometry. At the same time, Gram and hematoxylin-eosin stains of paraffin sections were performed to monitor the host responses. The data showed that gammadelta T lymphocytes increased significantly within the lungs after intranasal infection, and the peak of this cellular increase occurred at 5 days. Furthermore, at this time, greater than 50% of the CD3 T-cell receptor (TCR)-positive (CD3+) cells were gammadelta TCR positive. Histological examination clearly showed divergent inflammatory responses in the lungs of wild-type mice compared to gammadelta T-cell knockout mice. The C57BL/6J-Tcrd mice were less capable of clearing the organism, and the polymorphonuclear leukocyte response lasted longer than in wild-type C57BL/6J mice. These results showed that gammadelta T cells were actively involved in modulating the innate host responses to murine pulmonary infection by N. asteroides.     

A novel pathogenic RBP‐3 peptide reveals epitope spreading in persistent experimental autoimmune uveoretinitis

Experimental autoimmune uveoretinitis (EAU) in the C57BL/6J mouse is a model of non‐infectious posterior segment intraocular inflammation that parallels clinical features of the human disease. The purpose of this study was to analyse the immune response to the four murine subunits of retinol binding protein‐3 (RBP‐3) to identify pathogenic epitopes to investigate the presence of intramolecular epitope spreading during the persistent inflammation phase observed in this model of EAU. Recombinant murine subunits of the RBP‐3 protein were purified and used to immunize C57BL/6J mice to induce EAU. An overlapping peptide library was used to screen RBP‐3 subunit 3 for immunogenicity and pathogenicity. Disease phenotype and characterization of pathogenic subunits and peptides was undertaken by topical endoscopic fundal imaging, immunohistochemistry, proliferation assays and flow cytometry. RBP‐3 subunits 1, 2 and 3 induced EAU in the C57BL/6J mice, with subunit 3 eliciting the most destructive clinical disease. Within subunit 3 we identified a novel uveitogenic epitope, 629–643. The disease induced by this peptide was comparable to that produced by the uveitogenic 1–20 peptide. Following immunization, peptide‐specific responses by CD4⁺ and CD8⁺ T‐cell subsets were detected, and cells from both populations were present in the retinal inflammatory infiltrate. Intramolecular epitope spreading between 629–643 and 1–20 was detected in mice with clinical signs of disease. The 629–643 RBP‐3 peptide is a major uveitogenic peptide for the induction of EAU in C57BL/6J mice and the persistent clinical disease induced with one peptide leads to epitope spreading.     

Delayed clearance of Ehrlichia chaffeensis infection in CD4+ T-cell knockout mice

Human monocytic ehrlichiosis is an emerging tick-borne disease caused by the rickettsia Ehrlichia chaffeensis. To examine the role of helper T cells in host resistance to this macrophage-tropic bacterium, we assessed E. chaffeensis infections in three mouse strains with differing functional levels of helper T cells. Wild-type, C57BL/6J mice resolved infections in approximately 2 weeks. Major histocompatibility complex class II (MHCII) knockout, B6.129-Abb(tm1) mice lacking helper T cells developed persistent infections that were not resolved even after several months. CD4+ T-cell-deficient, B6.129S6-Cd4(tm1Knw) mice cleared the infection, but the clearance took 2 weeks longer than it did for wild-type mice. C57BL/6J mice resolved infection more rapidly following a second experimental challenge, but B6.129S6-Cd4(tm1Knw) mice did not. The B6.129S6-Cd4(tm1Knw) mice also developed active E. chaffeensis-specific immunoglobulin G responses that were slightly lower in concentration and slower to develop than that observed in C57BL/6J mice. E. chaffeensis-specific cytotoxic T cells were not detected following a single bacterial challenge in any mouse strain, including wild-type C57BL/6J mice. However, the cytotoxic T-cell activity developed in all three mouse strains, including the MHCII and CD4+ T-cell knockouts, when challenged with a second E. chaffeensis infection. The data reported here suggest that the cell-mediated immunity, orchestrated by CD4+ T cells is critical for conferring rapid clearance of E. chaffeensis.     

Immunological status of nude mice engrafted with allogeneic or syngeneic thymuses

Restoration of T-cell functions and changes in autoantibody production were studied in BALB/c nu/nu (nude) mice engrafted with syngeneic (BALB/c) or allogeneic (C57BL/6J) thymuses across major histocompatability barriers. T-cell functions, including mitogen responses and antibody production to sheep red blood cells (SRBC), were restored in nude mice engrafted with either allogeneic or syngeneic thymuses. Alloreactivity was evaluated by analysis of the pattern of skin allograft rejection, generation of alloreactive cytotoxic T-lymphocytes (CTLs), or quantitation of mixed-lymphocyte reaction (MLR). BABL/c nude mice engrafted with thymuses from newborn C57BL/6J mice accepted the skin from either thymus donor-type mice or from host-type mice. By contrast, such thymic chimeras rejected skin grafts from a third-party donor. CTLs from nude mice engrafted with C57BL/6J thymuses were cytotoxic to target cells of the third party but not to target cells of the host-type or of the thymus-type. In the MLR assay, spleen cells of nude mice engrafted with C57BL/6J thymuses responded vigorously to third party cells and only slightly to cells of the thymus-type. Low levels of serum IgG and high titers of IgM antibodies to nuclear antigens (but not dsDNA) or skin basal cells were also found in nude mice. Antibodies to both nuclear antigens and skin basal cells disappeared after transplantation of syngeneic thymuses, but not after transplantation of allogeneic thymuses. By contrast, serum IgG levels were restored to normal in nude mice engrafted with either syngeneic or allogeneic thymuses. These results suggest that either HLA-matched or HLA-mismatched thymus grafts may become a viable treatment for certain patients with T cell deficiencies associated with deficient development or maintenance of thymic structure and/or function.     

Stimulation of humoral antibody formation by polyanions. 3. Restoration of the immune response to sheep red blood cells by polyanions in thymectomized and lethally irradiated mice protected with bone marrow cells

Adult thymectomized C57BL/6J mice were lethally irradiated and injected 4 h later with 10 × 10⁶ syngeneic bone marrow cells. Two weeks later animals were either inoculated with sheep red blood cells alone or treated with synthetic polyanions such as dextran sulfate or polyacrylic acid prior to inoculation with sheep red blood cells. On the fifth day after immunization the mice treated with polyanions showed a 19 S and 7 S plaque-forming cell response as well as significant hemolytic titers. Control mice showed no significant plaque-forming cell response or hemolytic titers. Polyanions seem to be capable of replacing thymus cell function.     

IL-5-deficient mice are susceptible to experimental autoimmune encephalomyelitis

Experimental autoimmune encephalomyelitis (EAE) is an animal model commonly used to investigate mechanisms involved in the activation of self-reactive T cells. Whereas auto-reactive T(h)1 cells are believed to be involved in the generation of EAE, T(h)2 cells can induce EAE in immunocompromised hosts. Since the T(h)2 cytokine IL-5 can influence the nature and severity of disease, we investigated the role of IL-5 in the EAE model. Wild-type C57BL/6J and IL-5(-/-) mice were immunized with myelin oligodendrocyte glycoprotein (MOG)(35-55) peptide and the development of EAE observed. Our results show that IL-5(-/-) mice developed EAE with a similar day of onset and comparable severity to wild-type mice. Primed T cells isolated from IL-5(-/-) mice proliferated equally to wild-type cells in response to antigen challenge with MOG(35-55). Antigen-specific T cells from IL-5(-/-) mice produced IFN-gamma and tumor necrosis factor-alpha, but no IL-4 or IL-10, indicating that a predominant T(h)1 environment was induced following immunization. No differences in the types of cells infiltrating into the central nervous system were observed between IL-5(-/-) and wild-type mice. Our results suggest that IL-5 is not directly involved in the initiation or effector phase of MOG(35-55)-induced EAE in immunocompetent C57BL/6J mice.     

Mast cell-derived TNF contributes to airway hyperreactivity, inflammation, and TH2 cytokine production in an asthma model in mice

BACKGROUND: Mast cells, IgE, and TNF, which have been implicated in human atopic asthma, contribute significantly to the allergic airway inflammation induced by ovalbumin (OVA) challenge in mice sensitized with OVA without alum. However, it is not clear to what extent mast cells represent a significant source of TNF in this mouse model. OBJECTIVE: We investigated the importance of mast cell-derived TNF in a mast cell-dependent model of OVA-induced airway hyperreactivity (AHR) and allergic airway inflammation. METHODS: Features of this model of airway inflammation were analyzed in C57BL/6J-wild-type mice, mast cell-deficient C57BL/6J-Kit(W-sh)(/W-sh) mice, and C57BL/6J Kit(W-sh/W-sh) mice that had been systemically engrafted with bone marrow-derived cultured mast cells from C57BL/6J-wild-type or C57BL/6J-TNF(-/-) mice. RESULTS: Ovalbumin-induced AHR and airway inflammation were significantly reduced in mast cell-deficient Kit(W-sh/W-sh) mice versus wild-type mice. By contrast, Kit(W-sh/W-sh) mice that had been engrafted with wild-type but not with TNF(-/-) bone marrow-derived cultured mast cells exhibited responses very similar to those observed in wild-type mice. Mast cells and mast cell-derived TNF were not required for induction of OVA-specific memory T cells in the sensitization phase, but significantly enhanced lymphocyte recruitment and T(H)2 cytokine production in the challenge phase. CONCLUSION: Mast cell-derived TNF contributes significantly to the pathogenesis of mast cell-dependent and IgE-dependent, OVA-induced allergic inflammation and AHR in mice, perhaps in part by enhancing lymphocyte recruitment and T(H)2 cytokine production. CLINICAL IMPLICATIONS: Our findings in mice support the hypothesis that mast cell-derived TNF can promote allergic inflammation and AHR in asthma.     

Immune protection against HSV-2 in B-cell-deficient mice

The role of antibody in protection of the vaginal mucosa and sensory ganglia against HSV-2 infection was examined using HSV- immune, B-cell-deficient muMT mice. Significantly higher virus titers were detected in the vaginal mucosae of immune muMT mice compared to immune C57BL/6J mice 24 h after HSV-2 rechallenge. However, virus was rapidly cleared in immune muMT mice, and the infection was resolved with only a 2-day delay. Passive transfer of immune serum to immune muMT mice prior to rechallenge resulted in HSV-specific vaginal IgG levels comparable to those of immune C57BL/6J mice. Although transferred antibody failed to prevent reinfection of the majority of recipients, vaginal virus titers at 24 h and clearance kinetics were similar to those of immune C57BL/6J controls. Following vaginal rechallenge, HSV-2 did not spread to the sensory ganglia of immune C57BL/6J mice nor was the rechallenge virus detected in the ganglia of the majority of immune muMT mice. However, protection was severely compromised by T-cell depletion of immune C57BL/6J mice. These results suggest that HSV-specific antibody limits, but does not prevent, infection of the genital epithelia. Further, prevention of virus spread to the sensory ganglia in immune animals requires vigorous T-cell immune responses.     

噬菌体表达短肽模拟乙脑病毒糖蛋白的研究

为研究日本脑炎病毒 (JEV )E蛋白模拟肽 ,将抗JEVE蛋白的mAb 2H4淘筛噬菌体 15肽库。经夹心ELISA、竞争ELISA鉴定后 ,随机挑取 10个阳性克隆 ,测序并与JEVE蛋白同源比较。将阳性噬菌体免疫小鼠 ,检测血清中特异性抗体。ELISA结果显示筛选到的噬菌体能特异地与mAb 2H4结合 ,并且这种结合可被JEV天然抗原所竞争抑制。 10个阳性克隆的氨基酸序列相同 :—RQDPQWPYANSTIAR— ,同源分析得到的序列STXAR可能为mAb 2H4识别的模拟表位。阳性噬菌体表达的 15肽能够刺激小鼠产生特异性抗体。该噬菌体表达短肽模拟JEVE蛋白的部分抗原性。     

Virus expanded regulatory T cells control disease severity in the Theiler's virus mouse model of MS

Theiler's murine encephalomyelitis virus (TMEV)-induced demyelinating disease (TMEV-IDD) serves as virus-induced model of chronic progressive multiple sclerosis. Infection of susceptible SJL/J mice leads to life-long CNS virus persistence and a progressive autoimmune demyelinating disease mediated by myelin-specific T cells activated via epitope spreading. In contrast, virus is rapidly cleared by a robust CTL response in TMEV-IDD-resistant C57BL/6 mice. We investigated whether differential induction of regulatory T cells (Tregs) controls susceptibility to TMEV-IDD. Infection of disease-susceptible SJL/J, but not B6 mice, leads to rapid activation and expansion of Tregs resulting in an unfavorable CNS ratio of Treg:Teffector cells. In addition, anti-CD25-induced inactivation of Tregs in susceptible SJL/J, but not resistant B6, mice results in significantly decreased clinical disease concomitant with enhanced anti-viral CD4(+), CD8(+) and antibody responses resulting in decreased CNS viral titers. This is the first demonstration that virus-induced Treg activation regulates susceptibility to autoimmune disease differentially in susceptible and resistant strains of mice and provides a new mechanistic explanation for the etiology of infection-induced autoimmunity.     

Friend virus replication in normal and immunosuppressed C57BL/6 mice

Young adult C57BL/6 mice are resistant to the replication of Friend virus. We show here that this resistance is not absolute. In 7-week old C57BL/6 mice injected with NB-tropic Friend virus iv, high titers of SFFV could be recovered from the spleen at 8 days after infection but by 21 days, no virus was detectable. A single dose of anti-Thy 1.2 monoclonal antibody iv before FV infection permitted continued replication of SFFV in these animals. This finding strongly supports the hypothesis that SFFV replication in C57BL/6 mice is restricted by a T cell-mediated immune response.     

小鼠对雨蛙肽诱发急性胰腺炎易感性的品系差异

目的: 小鼠是常用于胰腺炎研究的模式动物。然而不同品系的小鼠似乎对胰腺炎有着不同的易感性,但缺乏系统的对比研究。我们因此比较了C57BL/6J、BALB/c和ICR 小鼠对雨蛙肽诱导的急性胰腺炎易感性的差异。方法: 2月龄C57BL/6J、BALB/c和ICR雌鼠各12只,随机分为实验组(n=6)和对照组(n=6)。实验组予以腹腔注射雨蛙肽(50 μg/kg),每小时1次,共注射7次;对照组同法注射等量生理盐水。分别于第1次注射后的0、3、6、9、12、24 h取小鼠血浆,并于24 h处死小鼠取其胰腺组织。测定各组小鼠的血浆淀粉酶和脂肪酶活性;观察其胰腺组织的病理形态学改变程度及炎症因子表达水平。结果: 雨蛙肽诱导胰腺炎后,BALB/c和ICR小鼠的血浆淀粉酶和脂肪酶水平较C57BL/6J小鼠升高更为显著;C57BL/6J小鼠与其它2种品系的小鼠相比,其胰腺病理形态学改变程度较轻,胰腺组织炎症因子表达水平也较低。结论: BALB/c和ICR小鼠对雨蛙肽诱导的急性胰腺炎的敏感性比C57BL/6J小鼠高。这一结果对急性胰腺炎研究中小鼠品系的合理选择具有指导意义。     

Effect of inactivation of the global oxidative stress regulator oxyR on the colonization ability of Escherichia coli O1:K1:H7 in a mouse model of ascending urinary tract infection

To survive within the host urinary tract, Escherichia coli strains that cause urinary tract infection (UTI) presumably must overcome powerful oxidant stresses, including the oxygen-dependent killing mechanisms of neutrophils. Accordingly, we assessed the global oxygen stress regulator OxyR of Escherichia coli as a possible virulence factor in UTI by determining the impact of oxyR inactivation on experimental urovirulence in CBA/J and C57BL (both wild-type and p47(phox-/-)) mice. The oxyR and oxyS genes of wild-type E. coli strain Ec1a (O1:K1:H7) were replaced with a kanamycin resistance cassette to produce an oxyRS mutant. During in vitro growth in broth or human urine, the oxyRS mutant exhibited the same log-phase growth rate (broth) and plateau density (broth and urine) as Ec1a, despite its prolonged lag phase (broth) or initial decrease in concentration (urine). The mutant, and oxyRS mutants of other wild-type ExPEC strains, exhibited significantly increased in vitro susceptibility to inhibition by H(2)O(2), which, like the altered growth kinetics observed with oxyRS inactivation, were reversed by restoration of oxyR on a multiple-copy-number plasmid. In CBA/J mice, Ec1a significantly outcompeted its oxyRS mutant (by >1 log(10)) in urine, bladder, and kidney cultures harvested 48 h after perurethral inoculation of mice, whereas an oxyR-complemented mutant exhibited equal or greater colonizing ability than that of the parent. Although C57BL mice were less susceptible to experimental UTI than CBA/J mice, wild-type and p47(phox-/-) C57BL mice were similarly susceptible, and the oxyR mutant of Ec1a was similarly attenuated in C57BL mice, regardless of the p47(phox) genotype, as in CBA/J mice. Within the E. coli Reference collection, 94% of strains were positive for oxyR. These findings fulfill the second and third of Koch's molecular postulates for oxyR as a candidate virulence-facilitating factor in E. coli and indicate that oxyR is a broadly prevalent potential target for future preventive interventions against UTI due to E. coli. They also suggest that neutrophil phagocyte oxidase is not critical for defense against E. coli UTI and that the major oxidative stresses against which OxyR protects E. coli within the host milieu are not phagocyte derived.     

In vitro acquisition of resistance against herpes simplex virus by permissive murine macrophages

Summary This study has documented that peritoneal macrophages (PM) from adult mice of strains DBA/2J, BALB/c and AKR can support productive replication of herpes simplex virus (HSV) strains Thea and Haase. Simian virus 40 transformed PM of C57 BL/6J origin yielded high titers of Thea and Haase, whereas normal PM from adult mice of the same genetic background were infected abortively. The evidence obtained suggested that multiplication of PM per se is insufficient to allow HSV replication. PM from DBA/2J mice, immune to HSV or Listeria monocytogenes lacked the capacity to support productive replication of HSV. PM from nonimmune, adult DBA/2J or suckling C57BL/6J mice acquired the potential to effectively restrict HSV replication when preincubated for 24 hours with 72 hours old MLC supernatant. These macrophages could also inhibit HSV replication if pretreated with supernatant from cultures of specific antigen stimulated, HSV or Listeria immune spleen lymphocytes (SL). Likewise, supernatant from concanavalin A stimulated SL also possessed the capacity to confer resistance against HSV replication in otherwise permissive PM. Sensitized T cells proved to be essential for the generation of active supernatants. Active supernatants had the potential to confer resistance against HSV replication within mouse but not chick or hamster embryo cells. The other characteristics of the soluble mediator included: instability at pH 2, inactivation by trypsin but not by DNase or RNase and persistence of activity when exposed to 56° C for 20 minutes.With 3 Figures     

Strain-dependent requirement for IFN-γ for respiratory control and immunotherapy in murine gammaherpesvirus infection

Interferon-γ (IFN-γ) and perforin (pfp) are important effector mechanisms used by CD8 T cells to clear virus-infected cells. In this study, we used IFN-γ/pfp double knockout mice to address if these two effector molecules play redundant roles in the control of acute infection with murine gammaherpesvirus-68 (MHV-68) in BALB/C mice. Perforin knockout (KO) mice and wild-type mice cleared infectious virus from the lungs, even following high-dose infection. However, the IFN-γ KO and IFN-γ/pfp double knockout (DKO) groups had higher virus titers in the lungs at day 10 post-infection, and both groups had higher mortality rates. In IFN-γ/pfp DKO mice, the virus titer and mortality rate were significant higher than in IFN-γ KO mice, indicating a role for perforin in protection from disease. WT mice given IFN-γ blocking antibody also showed significantly higher viral titers. In contrast, IFN-γ KO mice on a C57BL/6 background controlled respiratory infection comparably to wild-type mice. These data show that perforin plays a redundant role in the control of virus replication, but IFN-γ plays an essential role in BALB/C mice infected with MHV-68. We conclude that there is a marked strain-dependent difference in the effector mechanisms needed to control acute MHV-68 infection between C57BL/6 and BALB/C mice. In addition we show that immune therapy that re-establishes viral control after spontaneous reactivation in CD4-deficient mice depends upon perforin in C57BL/6 mice but IFN-γ in BALB/C mice.