Alphavirus-Specific Cytotoxic T Lymphocytes Recognize a Cross-Reactive Epitope from the Capsid Protein and Can Eliminate Virus from Persistently Infected Macrophages

Persistent alphavirus infections in synovial and neural tissues are believed to be associated with chronic arthritis and encephalitis, respectively, and represent likely targets for CD8⁺ αβ cytotoxic T lymphocytes (CTL). Here we show that the capsid protein is a dominant target for alphavirus-specific CTL in BALB/c mice and that capsid-specific CTL from these mice recognize an H-2K^d restricted epitope, QYSGGRFTI. This epitope lies in the highly conserved region of the capsid protein, and QYSGGRFTI-specific CTL were cross reactive across a range of Old World alphaviruses. In vivo the acute primary viraemia of these highly cytopathic viruses was unaffected by QYSGGRFTI-specific CTL. However, in vitro these CTL were able to completely clear virus from macrophages persistently and productively infected with the arthrogenic alphavirus Ross River virus.     

Immune Response to other Agents of Calves Persistently Infected with Bovine Virus Diarrhoea Virus (BVDV)

The ability of calves persistently infected (PI) with bovine virus diarrhoea virus BVDV to respond immunologically to defined antigens other than BVDV was studied. Five clinically healthy PI calves were studied together with 5 non-PI calves serving as controls. The humoral immune response was tested by measuring the serum antitoxin titre following immunization against tetanus. The cellular immune response was tested by the ability to develop a positive reaction in a cutaneous tuberculin test performed 1 month after immunization against Johne’s disease (paratuberculosis). Finally, a skin-sensitizing agent, dinitrochlorobenzene (DNCB), was employed to study whether PI calves would react by hypersensitization following skin exposure to DNCB for 7 consecutive days followed by application of DNCB to a new skin area remote from the area that had first been exposed. The response of PI calves to the various types of antigenic stimuli applied was not significantly different from that of the control calves. Thus, PI calves developed a potent antitoxin response after tetanus immunization, they showed a positive reaction to tuberculin skin test after immunization against paratuberculosis, and were skin sentitized with DNCB.     

Cells Persistently Infected with Newcastle Disease Virus: II. Ribonucleic Acid and Protein Synthesis in Cells Infected with Mutants Isolated from Persistently Infected L Cells

A comparison of the replication patterns in L cells and in chick embryo (CE) cell cultures was carried out with the Herts strain of Newcastle disease virus (NDV(o)) and with a mutant (NDV(pi)) isolated from persistently infected L cells. A significant amount of virus progeny, 11 plaque-forming units (PFU)/cell, was synthesized in L cells infected with NDV(o), but the infectivity remained cell-associated and disappeared without being detectable in the medium. In contrast, in L cells infected with NDV(pi), progeny virus (30 PFU/cell) was released efficiently upon maturation. It is suggested that the term "covert" rather than "abortive" be used to describe the infection of L cells with NDV(o). In both L and CE cells, the latent period of NDV(pi) was 2 to 4 hr longer than for NDV(o). The delay in synthesis of viral ribonucleic acid (RNA) in the case of NDV(pi) coincided with the delay in the inhibition of host RNA and protein synthesis. Although both NDV(o) and NDV(pi) produced more progeny and more severe cell damage in CE cells than in L cells, the shut-off of host functions was significantly less efficient in CE cells than in L cells. Paradoxically, no detectable interferon was produced in CE cells by either of the viruses, whereas in L cells most of the interferon appeared in the medium after more than 90% of host protein synthesis was inhibited. These results suggest that the absence of induction of interferon synthesis in CE cells infected with NDV is not related to the general shut-off of host cell synthetic mechanisms but rather to the failure of some more specific event to occur. In spite of the fact that NDV(pi) RNA synthesis commenced 2 to 4 hr later than that of NDV(o), interferon was first detected in the medium 8 hr after infection with both viruses. This finding suggests that there is no relation between viral RNA synthesis and the induction of interferon synthesis.     

Cells Persistently Infected with Newcastle Disease Virus III. Thermal Stability of Hemagglutinin and Neuraminidase of a Mutant Isolated from Persistently Infected L Cells

Data were obtained which indicated the possible cause of the defective elution from erythrocytes of the mutant virus (NDV(pi)) isolated from L cells persistently infected with the Herts strain of Newcastle disease virus (NDV(o)). The chicken erythrocyte receptors for the mutant and wild-type viruses were equally sensitive to the action of Vibrio cholera filtrate neuraminidase; this suggests that the failure of NDV(pi) to elute from chicken erythrocytes is not due to a specific neuraminidase-resistant receptor for this virus on the erythrocyte membrane. There was no difference in the enzyme content of the intact virions of NDV(o) and NDV(pi) when tested with a soluble substrate, indicating that the inefficient elution of NDV(pi) was not due to a reduced enzyme content. The neuraminidase activity of intact NDV(pi) virions was significantly more stable at 55 C than the enzyme of NDV(o) virions, whereas the dissociated enzymes of the two viruses were inactivated at the same rate. On the basis of these findings, it seems likely there is a structural difference between the two viruses. The neuraminidase protein of the mutant NDV(pi) may be incorporated into the viral envelope in such a manner that it is prevented from reacting with the substrate in the erythrocyte membrane, although it can react with a soluble substrate. The hemagglutinin activity of both intact and disrupted NDV(pi) was significantly more resistant to thermal inactivation than that of the wild-type NDV(o). This finding suggests a genetic difference in the hemagglutinin protein of the two viruses.     

Clearance of Measles Virus from Persistently Infected Cells by Short Hairpin RNA

Subacute sclerosing panencephalitis (SSPE) is a demyelinating central nervous system disease caused by a persistent measles virus (MV) infection of neurons and glial cells. There is still no specific therapy available, and in spite of an intact innate and adaptive immune response, SSPE leads inevitably to death. In order to select effective antiviral short interfering RNAs (siRNAs), we established a plasmid-based test system expressing the mRNA of DsRed2 fused with mRNA sequences of single viral genes, to which certain siRNAs were directed. siRNA sequences were expressed as short hairpin RNA (shRNA) from a lentiviral vector additionally expressing enhanced green fluorescent protein (EGFP) as an indicator. Evaluation by flow cytometry of the dual-color system (DsRed and EGFP) allowed us to find optimal shRNA sequences. Using the most active shRNA constructs, we transduced persistently infected human NT2 cells expressing virus-encoded HcRed (piNT2-HcRed) as an indicator of infection. shRNA against N, P, and L mRNAs of MV led to a reduction of the infection below detectable levels in a high percentage of transduced piNT2-HcRed cells within 1 week. The fraction of virus-negative cells in these cultures was constant over at least 3 weeks posttransduction in the presence of a fusion-inhibiting peptide (Z-Phe-Phe-Gly), preventing the cell fusion of potentially cured cells with persistently infected cells. Transduced piNT2 cells that lost HcRed did not fuse with underlying Vero/hSLAM cells, indicating that these cells do not express viral proteins any more and are “cured.” This demonstrates in tissue culture that NT2 cells persistently infected with MV can be cured by the transduction of lentiviral vectors mediating the long-lasting expression of anti-MV shRNA.The neurodegenerative human disease subacute sclerosing panencephalitis (SSPE) occurs with an incidence rate of approximately 1:10,000 after infection with wild-type measles virus (MV) (4, 38). The course of the illness is quite variable, usually lasting from 1 to 3 years. Much more rapid forms that lead to death within a few months as well as prolonged courses with a duration of more than 20 years have been described (40). Neuropathological findings include diffuse encephalitis, affecting both the gray and white matters, characterized by perivascular cuffing and diffuse lymphocytic infiltrations. Neurons, oligodendrocytes, fibrous astrocytes, and some brain microvascular endothelial cells contain large aggregates of intranuclear inclusion bodies consisting of MV nucleocapsid structures (1, 16). In these persistently infected cells, viral ribonucleoprotein particles (RNPs) replicate intracellularly, whereas the budding of complete viruses and cell-cell fusion are not observed. A characteristic feature of this central nervous system disease is that the expression of viral envelope proteins (matrix [M], fusion [F], and hemagglutinin [H] proteins) is restricted by various means. In particular, the M protein and the cytoplasmic part of the F protein harbor single or hypermutations or deletions, which prevent their proper expression (2, 3, 9, 10). The lack of M reduces budding, supports cell fusion, and enhances the intracellular replication of RNPs (7, 8, 32, 37). As far as is known, the cell-to-cell spread of infectivity in the human brain occurs in the presence of normal cellular and strong humoral antiviral immune responses with very high anti-MV antibody titers in the cerebrospinal fluid. This, however, cannot prevent virus spread.A variety of approaches to the treatment of SSPE have been attempted, but an evaluation of their efficiency has been extremely difficult, since clinical trials are based on small numbers of patients, the course of SSPE is highly variable, and spontaneous remissions may also occur. Intrathecal or intraventricular administration of alpha interferon, inosiplex, and/or ribavirin is a common regimen, but despite many efforts, the establishment of an effective therapy has not been possible. Since the immune systems of the patients appear normal, and given the fact that virus spreads in the form of intracellular RNPs, a promising specific therapy must target this intracellular replication of MV.RNA interference (RNAi) may provide such a means and has already been used successfully to inhibit the expression of a number of viral infections, including the Ebola, influenza A, hepatitis B and C, human immunodeficiency, respiratory syncytial, and West Nile viruses, and several RNAi-based therapeutics are already in preclinical test phases (for reviews, see references 6 and 24). Small interfering RNAs (siRNAs) have also been described to be active against MV (20, 29, 32), including an MV isolate from an SSPE patient (SSPE-Kobe-1) (28). In the latter approach, the authors generated recombinant adenoviruses (rAdV) expressing siRNA against MV L mRNA and assessed them in freshly infected Vero/SLAM cells. In contrast to this work, we constructed lentiviral vectors expressing short hairpin RNAs (shRNAs) and transduced persistently infected human NT2 cells with these vectors. This lentiviral approach provided the proof of principle that a preexisting persistent MV infection can be cured by shRNA.     

Measles Virus-Specified Polypeptide Synthesis in Two Persistently Infected HeLa Cell Lines

Measles virus-directed protein synthesis was examined in two HeLa cell lines (K11 and K11A) that are persistently infected with wild-type measles virus. Four viral proteins (H, hemagglutination protein; P, nucleocapsid-associated protein; NP, the major nucleocapsid protein; and M, the matrix protein) were readily detected in both cell lines by immune precipitation of [(35)S]methionine-labeled cell extracts followed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. When analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, three (H, NP, and M) of the four viral proteins in both K11 and K11A cells differed from the corresponding viral proteins synthesized in HeLa cells acutely infected with the parental wild-type virus. In addition, the M protein from K11A cells migrated significantly more slowly on sodium dodecyl sulfate-polyacrylamide gel electrophoresis than the M protein from K11 cells, and there appeared to be slight differences in the H and NP proteins between these two persistently infected cell lines. The altered viral proteins detected in K11 and K11A cells appeared to be the result of viral mutations rather than changes in the host cell, since virus recovered from these cells directed the synthesis of similar aberrant viral proteins in HeLa cells. Virus recovered from K11 cells and virus recovered from K11A cells were both temperature sensitive and grew more slowly than wild-type virus. HeLa cells infected with virus recovered from K11 cells readily became persistently infected, resembling the original persistently infected K11 cells. Thus, viral mutations are associated with persistent measles virus infections in cell cultures.     

Temperature-Sensitive Mutants Isolated from L Cells Persistently Infected with Newcastle Disease Virus

Virus mutants (NDV(pi)) isolated from L cells persistently infected with the Herts strain of Newcastle disease virus have been previously reported by this laboratory to differ from the wild-type virus (NDV(o)) in several physical and biological properties. It has now been determined that, in addition to these differences, the NDV(pi) mutants are also spontaneously selected temperature-sensitive mutants. The temperature sensitivity of 10 NDV(pi) clones was confirmed by temperature inhibition, plaquing efficiency, and single-cycle yield experiments. The cut-off temperature, at which more than 90% of virus replication is inhibited was between 41 and 42 C. All 10 NDV(pi) clones were also found to be defective in virus-specific ribonucleic acid (RNA) synthesis in infected chick embryo cells at 42 C and are tentatively classified as RNA(-). The possible relationships of the temperature sensitivity, the other NDV(pi) properties, and the maintenance of the persistently infected state are discussed.     

猪瘟病毒野毒株持续感染细胞模型的建立

采用猪瘟病毒野毒珠（ＣＳＦＶ３９）感染猪肾传代细胞系ＰＫ－１５,经连续传７９代,建立了稳定的病毒持续感染细胞模型,获得ＣＳＦＶ３９－ＰＫ１５细胞株。用免疫荧光、ＲＴ－ＰＣＲ检测、透射电镜跟踪观察了ＣＳＦＶ３９－ＰＫ１５细胞株连续传代中病毒在细胞内的存在情况。结果表明第９,２９,７９代细胞仍有猪瘟病毒存在,表现出病毒持续感染的基本特征。这为深入研究猪瘟病毒持续感染机理奠定了基础。     

猪瘟病毒野毒株持续感染细胞模型的建立

采用猪瘟病毒野毒珠(CSFV39)感染猪肾传代细胞系PK-15,经连续传79代,建立了稳定的病毒持续感染细胞模型,获得CSFV39-PK15细胞株.用免疫荧光、RT-PCR检测、透射电镜跟踪观察了CSFV39-PK15细胞株连续传代中病毒在细胞内的存在情况.结果表明第9,29,79代细胞仍有猪瘟病毒存在,表现出病毒持续感染的基本特征.这为深入研究猪瘟病毒持续感染机理奠定了基础.     

Temperature-Sensitive Defect of Mutants Isolated from L Cells Persistently Infected with Newcastle Disease Virus

The temperature-sensitive defects of virus mutants isolated from L cells persistently infected with Newcastle disease virus (NDV) were analyzed. Genetic grouping of the mutants by complementation tests was attempted by using several different methods, including yield analysis, RNA synthesis, and heterozygote formation at 42 to 43 C, the nonpermissive temperature. In each case, specific interference prevented detection of complementation. This interference was shown to occur prior to or at the level of virus RNA synthesis. Temperature-shift experiments with five different NDV(pi) clones showed that virus replication begun at 37 C could not be completed at the nonpermissive temperature. The activity of the NDV-specific RNA-dependent RNA polymerase in the cytoplasm of infected chicken embryo cells was not stable and could not be demonstrated directly. However, indirect measurement of RNA polymerase activity at the nonpermissive temperature was accomplished by studying the kinetics of virus-specific RNA synthesis in infected cells after temperature shift. Two types of response were obtained: with three NDV(pi) clones, virus-specific RNA synthesis ceased immediately upon transfer of infected cells to 42 to 43 C, whereas in cells infected with two other NDV(pi) clones, RNA synthesis continued for several hours at this temperature. These results suggested that there may be two types of ts defects in NDV(pi), both associated with virus-specific RNA polymerase activity.     

DNA Synthesis in Tobacco Mosaic Virus-Infected Nicotiana tabacum Protoplasts and Regeneration of Persistently Infected Calli

Tobacco mosaic virus infection of Nicotiana tabacum mesophyll protoplasts did not affect the pattern of chloroplast or total cellular DNA synthesis for at least 120 h when compared with that of mock-infected cells. Calli derived from infected protoplasts often showed large amounts of tobacco mosaic virus RNA and coat protein.     

Generation of a Persistently Infected MDBK Cell Line with Natural Bovine Spongiform Encephalopathy (BSE)

Bovine spongiform encephalopathy (BSE) is a zoonotic transmissible spongiform encephalopathy (TSE) thought to be caused by the same prion strain as variant Creutzfeldt-Jakob disease (vCJD). Unlike scrapie and chronic wasting disease there is no cell culture model allowing the replication of proteinase K resistant BSE (PrP^BSE) and the further in vitro study of this disease. We have generated a cell line based on the Madin-Darby Bovine Kidney (MDBK) cell line over-expressing the bovine prion protein. After exposure to naturally BSE-infected bovine brain homogenate this cell line has shown to replicate and accumulate PrP^BSE and maintain infection up to passage 83 after initial challenge. Collectively, we demonstrate, for the first time, that the BSE agent can infect cell lines over-expressing the bovine prion protein similar to other prion diseases. These BSE infected cells will provide a useful tool to facilitate the study of potential therapeutic agents and the diagnosis of BSE.     

Severe Leukopenia and Dysregulated Erythropoiesis in SCID Mice Persistently Infected with the Parvovirus Minute Virus of Mice

Parvovirus minute virus of mice strain i (MVMi) infects committed granulocyte-macrophage CFU and erythroid burst-forming unit (CFU-GM and BFU-E, respectively) and pluripotent (CFU-S) mouse hematopoietic progenitors in vitro. To study the effects of MVMi infection on mouse hemopoiesis in the absence of a specific immune response, adult SCID mice were inoculated by the natural intranasal route of infection and monitored for hematopoietic and viral multiplication parameters. Infected animals developed a very severe viral-dose-dependent leukopenia by 30 days postinfection (d.p.i.) that led to death within 100 days, even though the number of circulating platelets and erythrocytes remained unaltered throughout the disease. In the bone marrow of every lethally inoculated mouse, a deep suppression of CFU-GM and BFU-E clonogenic progenitors occurring during the 20- to 35-d.p.i. interval corresponded with the maximal MVMi production, as determined by the accumulation of virus DNA replicative intermediates and the yield of infectious virus. Viral productive infection was limited to a small subset of primitive cells expressing the major replicative viral antigen (NS-1 protein), the numbers of which declined with the disease. However, the infection induced a sharp and lasting unbalance of the marrow hemopoiesis, denoted by a marked depletion of granulomacrophagic cells (GR-1⁺ and MAC-1⁺) concomitant with a twofold absolute increase in erythroid cells (TER-119⁺). A stimulated definitive erythropoiesis in the infected mice was further evidenced by a 12-fold increase per femur of recognizable proerythroblasts, a quantitative apoptosis confined to uninfected TER-119⁺ cells, as well as by a 4-fold elevation in the number of circulating reticulocytes. Therefore, MVMi targets and suppresses primitive hemopoietic progenitors leading to a very severe leukopenia, but compensatory mechanisms are mounted specifically by the erythroid lineage that maintain an effective erythropoiesis. The results show that infection of SCID mice with the parvovirus MVMi causes a novel dysregulation of murine hemopoiesis in vivo.     

Differentiation of hemagglutinins in tissues infected withChlamydia

Crude, soluble, chlamydial hemagglutinin was prepared from allantoic fluid harvested from embryonated chick eggs and the supernatant fluid of mouse L cells infected with eitherChalamydia psittaci strain 6BC orChlamydia trachomatis strain TW-3. Control nonhemagglutinating specimens of uninfected allantoic fluid and mouse L cells were also prepared. The six preparations were separated by ether-ethanol extraction into lipid-rich and lipid-depleted fractions. Complement-fixing activity was found in the lipid-rich (but not in the lipid-depleted) fraction of infected preparations. In contrast, lipid-rich fractions of infected and uninfected preparations had similar agglutinating activity when sensitive erythrocytes of white Leghorn chickens were used. The lipid-rich fraction of infected and uninfected preparations was separated by thin-layer chromatography (TLC) into seven components with similarR _f values, hemagglutinating patterns, and chemical composition (lipid, protein, and carbohydrate). The highest hemagglutination titers of normal and infected preparations were found in a TLC fraction with similarR _f values and contained lipid, protein, and carbohydrate. This TLC fraction fromC. psittaci 6BC preparations was used in hemagglutination-inhibition studies. The results indicated that chlamydial hemagglutinin extracted by ether-ethanol and separated by TLC contained, in addition to specific hemagglutinin, nonspecific tissue-lipid hemagglutinin(s) identical to that found in normal preparations.     

Characterization of Measles Virus-Specific Proteins Synthesized In Vivo and In Vitro from Acutely and Persistently Infected Cells

Measles virus protein synthesis has been analyzed in acutely and persistently infected cells. To assess the role of measles in subacute sclerosing panencephalitis (SSPE), measles viral proteins synthesized in vivo or in vitro were tested for reactivity with serum from a guinea pig(s) immunized with measles virus and sera from patients with SSPE. Guinea pig antimeasles virus serum immunoprecipitates the viral polypeptides of 78,000 molecular weight (glycosylated [G]), 70,000 molecular weight (phosphorylated [P]), 60,000 molecular weight (nucleocapsid [N]), and 35,000 molecular weight (matrix [M]) from cells acutely infected with measles virus as well as from chronically infected cells, but in the latter case, immunoprecipitated M protein has a reduced electrophoretic migration. Sera of SSPE patients immunoprecipitated all but the G protein in acutely infected cells and only the P and N proteins from chronically infected cells. In immunoprecipitates of viral polypeptides synthesized in a reticulocyte cell-free translation system, in response to mRNA from acutely or persistently infected cells, the 78,000-molecular-weight form of the G protein was not detected among the cell-free products of either mRNA. Guinea pig antimeasles virus serum immunoprecipitated P, N, and M polypeptides from the products of either form of mRNA, whereas SSPE serum immunoprecipitated the P and N polypeptides but not the M polypeptide. The differences in immunoreactivity of the antimeasles virus antiserum and the SSPE serum are discussed in terms of possible modifications of measles virus proteins in SSPE.     

Persistent infection of HeLa-229 cells withChlamydia trachomatis

A persistent infection of HeLa-229 cells was established withChlamydia trachomatis strain B/TW-5/OT. A low multiplicity of infection (0.01) was used with no chemical or physical pretreatment of the cell cultures. Lymphogranuloma venereum straiN L2/434/BU did not establish a persistent infection under identical conditions.     

The Cytokine Response of U937-Derived Macrophages Infected through Antibody-Dependent Enhancement of Dengue Virus Disrupts Cell Apical-Junction Complexes and Increases Vascular Permeability

Severe dengue (SD) is a life-threatening complication of dengue that includes vascular permeability syndrome (VPS) and respiratory distress. Secondary infections are considered a risk factor for developing SD, presumably through a mechanism called antibody-dependent enhancement (ADE). Despite extensive studies, the molecular bases of how ADE contributes to SD and VPS are largely unknown. This work compares the cytokine responses of differentiated U937 human monocytic cells infected directly with dengue virus (DENV) or in the presence of enhancing concentrations of a humanized monoclonal antibody recognizing protein E (ADE-DENV infection). Using a cytometric bead assay, ADE-DENV-infected cells were found to produce significantly higher levels of the proinflammatory cytokines interleukin 6 (IL-6), IL-12p70, and tumor necrosis factor alpha (TNF-α), as well as prostaglandin E₂ (PGE₂), than cells directly infected. The capacity of conditioned supernatants (conditioned medium [CM]) to disrupt tight junctions (TJs) in MDCK cell cultures was evaluated. Exposure of MDCK cell monolayers to CM collected from ADE-DENV-infected cells (ADE-CM) but not from cells infected directly led to a rapid loss of transepithelial electrical resistance (TER) and to delocalization and degradation of apical-junction complex proteins. Depletion of either TNF-α, IL-6, or IL-12p70 from CM from ADE-DENV-infected cells fully reverted the disrupting effect on TJs. Remarkably, mice injected intraperitoneally with ADE-CM showed increased vascular permeability in sera and lungs, as indicated by an Evans blue quantification assay. These results indicate that the cytokine response of U937-derived macrophages to ADE-DENV infection shows an increased capacity to disturb TJs, while results obtained with the mouse model suggest that such a response may be related to the vascular plasma leakage characteristic of SD.     

Evaluation of Cytokine Production and Phagocytic Activity in Mice Infected with Campylobacter jejuni

The effect of several Campylobacter jejuni strains on the immune response was analyzed in mice after intraperitoneal inoculation with 10¹⁰ colony forming units (CFU). Three C. jejuni strains were assayed: CCUG 6968 (enterotoxigenic), CCUG 7580 (enterotoxigenic), and CCUG 7440 (non-enterotoxigenic). These C. jejuni strains induced a peritoneal inflammatory response and an important increase in the peritoneal phagocyte oxidative activity measured by chemiluminescence assay, as well as an increase in the number of peritoneal cells. Both interleukin-1 (IL-1) and tumor necrosis factor α (TNFα) production by peritoneal cells were not modified. However, C. jejuni 7440 caused a statistically significant increase in TNFα production. These results have demonstrated that different strains of C. jejuni induce an increase of the inflammatory response without a significant cytokine release. However, these infectious microorganisms may be eliminated efficiently by murine macrophages after phagocytosis. Received: 18 February 1999 / Accepted: 6 May 1999     

Adenosine Deaminase Activity in Serum and Lymphocytes of Rats Infected with Sporothrix schenckii

Sporotrichosis is a fungal infection of subcutaneous or chronic evolution, inflammatory lesions characterized by their pyogranulomatous aspect, caused by the dimorphic fungus Sporothrix schenckii. Adenosine deaminase (ADA) is a "key" enzyme in the purine metabolism, promoting the deamination of adenosine, an important anti-inflammatory molecule. The increase in ADA activity has been demonstrated in several inflammatory conditions; however, there are no data in the literature associated with this fungal infection. The objective of this study was to evaluate the activity of serum ADA (S-ADA) and lymphocytes (L-ADA) of rats infected with S. schenckii. We used seventy-eight rats divided into two groups. In the first experiment, rats were infected subcutaneously and in the second experiment, infected intraperitoneally. Blood samples for hematologic evaluation and activities of S-ADA and L-ADA were performed at days 15, 30, and 40 post-infection (PI) to assess disease progression. In the second experiment, it was observed an acute decrease in activity of S-ADA and L-ADA (P?相似文献