CD44-Associated Tn Antigen as a New Biomarker of Tumor Cells with Aberrant Glycosylation.

Tn antigen is a tumor-associated antigen that appears on cancer cells as a result of aberrant O-glycosylation. The most studied form of Tn antigen is found in mucins, in particular, in mucin 1 (MUC1). Antibodies against this form of Tn antigen are used to diagnose tumors, as well as to generate T-killers with a chimeric receptor. Some carcinomas do not carry MUC1 and antibodies of a different specificity are required to detect Tn antigen on these cells. In our work, we searched for anti-Tn antibodies without preliminary assumptions about the proteins that may be carriers of the Tn antigen. For this purpose, we obtained several pairs of isogenic cell lines with the wild type and knockout of the Cosmc gene, which is essential for correct protein O-glycosylation. Using the created lines as immunogens, we generated a monoclonal antibody AKC3, which reacted with the Cosmc-deficient A549 lung adenocarcinoma cells and did not bind to the wild-type cells. Using mass spectrometry, as well as co-immunoprecipitation, it was shown that the AKC3 antibody recognized the Tn antigen in the context of CD44 protein - a protein important for tumor growth. The AKC3 antibody can be used for tumor diagnosis, and to generate T cells with a chimeric receptor for treatment of tumors that do not express mucins.

Pharmaceutical grade synthetic peptide Thr-Glu-Lys-Lys-Arg-Arg-Glu-Thr-Val-Glu-Arg-Glu-Lys-Glu ameliorates DSS-induced murine colitis by reducing the number and pro-inflammatory activity of colon tissue-infiltrating Ly6G+ granulocytes and Ly6C+ monocytes.

A pharmaceutical grade synthetic tetradecapeptide Thr-Glu-Lys-Lys-Arg-Arg-Glu-Thr-Val-Glu-Arg-Glu-Lys-Glu (GEPON) that mimics the ezrin protein hinge region was studied in dextran sodium sulphate-induced murine experimental colitis (DSS colitis). We report that GEPON intraperitoneal injections significantly attenuated DSS-induced pathological manifestations in the large intestine, bloody diarrhoea, and body weight loss in C57BL/6 mice. GEPON markedly inhibited the transcription rate of pro-inflammatory Il1b, Il6, and Nos2 genes in the colon tissue, in contrast with those encoding anti-inflammatory factors, such as Tgfb1, I10, and Arg1, whose transcription rate did not change significantly. Using flow cytometry, we found that GEPON treatment significantly reduced the accumulation of Ly6G+ granulocytes and Ly6C+ monocytes in the colon infiltrate of DSS colitis mice. Analysis of the mRNA level in myeloid cells sorted from the colon tissue revealed that GEPON had decreased the expression of pro-inflammatory genes in both colon-infiltrating Ly6G+ granulocytes and Ly6C+ monocytes, but not in Ly6C-CD64+ macrophages of DSS-treated mice. The direct anti-inflammatory impact of GEPON was shown in an in vitro culture of Ly6C+ monocytes, as evidenced by an inhibition of IL-1 beta and IL-6 mRNA expression. Taken together, our results demonstrated that GEPON had a pronounced therapeutic effect on ulcerative colitis in a laboratory mice model and provided evidence of its curative efficacy via inhibition of colon tissue inflammation by decreasing Ly6G+ granulocyte and Ly6C+ monocyte infiltration and by reducing their pro-inflammatory activities.

[A comparative study of the efficacy and safety of the eyebrow supraorbital approach in cerebral aneurysm surgery]. / Sravnitel'noe issledovanie éffektivnosti i bezopasnosti transbrovnogo supraorbital'nogo dostupa v khirurgii anevrizm golovnogo mozga.

OBJECTIVE: The study objective was to compare the efficacy and safety of supraorbital eyebrow (SEA) and pterional (PA) approaches in surgery of anterior circle of Willis (ACW) aneurysms and to determine the advantages and disadvantages of SEA in aneurysm clipping. MATERIAL AND METHODS: The analysis included 166 patients with ACW aneurysms aged 18 to 70 years who were treated in the Neurosurgery Department of the Interregional Clinical Diagnostic Center (Kazan) in the period from 2013 to 2016. At the first stage of the study, factors affecting surgical outcomes were compared (by using the Glasgow outcome scale (GOS)) in subpopulations of patients operated on using SEA (n=49) and PA (n=117). At the second stage, we compared the efficacy and safety of approaches using a case-control subanalysis in appropriate subgroups of the SEA (n=37) and PA (n=37) groups. The subgroups were comparable in the following factors: gender, age, severity of subarachnoid hemorrhage (SAH) on (Fisher scale), severity of the patient's condition (Hunt-Hess scale), size and location of the aneurysm, surgery duration, intraoperative aneurysm rupture (IOAR), amount of blood loss, rate of frontal sinus surgery, rate of nasal CSF leak, rate of intraoperative and postoperative complications, hemorrhagic and ischemic complications according to postoperative CT, patient's satisfaction with the cosmetic result of surgery (visual analogue scale - VAS), and treatment outcomes (GOS). Treatment outcomes (GOS) and patient's satisfaction with the cosmetic result of surgery (VAS) were considered as the efficacy parameters. The safety parameters included the amount of blood loss, rate of frontal sinus surgery, rate of nasal CSF leak, and rate of intraoperative and postoperative (hemorrhagic and ischemic) complications. RESULTS: At the first stage of the study, we found that the amount of intraoperative blood loss in the subpopulation of patients with ACW aneurysms who were operated on using SEA was statistically significantly less than that in the PA group (p=0.0000002). In the postoperative period, patients who underwent surgery using SEA less frequently experienced neurological deficit (p=0.003), less frequently developed first epileptic seizures (p=0.035), and had a lower rate of hemorrhagic complications (p=0.003) and better treatment outcomes (GOS) (p=0.01). Comparison of appropriate subgroups in the SEA and PA groups, which were selected according to the case-control methodology and were comparable in the main factors affecting treatment outcomes, confirmed statistically significantly lower blood loss for SEA (p=0.0000002) than for PA. Compared to the SEA group, the PA group was characterized by more frequent, but not statistically significantly different, IOAR (p=1), postoperative worsening of neurological deficit (p=0.115), newly developed epileptic seizures (p=0.493), and hemorrhagic complications (p=0.0557). There were no deaths in both groups. In the SEA group, the treatment outcome was scored 4 and 5 (GOS, favorable outcome); in the PA group, the treatment outcome was scored 3 (GOS) in 2 (5.4%) patients and 4 or 5 in 35 (94.6%) patients (p=0.063). The mean subjective score of satisfaction with the treatment result (VAS) in the SEA group was significantly higher (9.4±1) than in the PA group (8.8±1; p=0.01). CONCLUSION: SEA is an adequate approach for clipping ACW aneurysms, in particular ACA-AComA and MCA aneurysms, which is as effective and safe as the pterional approach.

An asymptotic higher-order theory for rectangular beams.

A direct asymptotic integration of the full three-dimensional problem of elasticity is employed to derive a consistent governing equation for a beam with the rectangular cross section. The governing equation is consistent in the sense that it has the same long-wave low-frequency behaviour as the exact solution of the original three-dimensional problem. Performance of the new beam equation is illustrated by comparing its predictions against the results of direct finite-element computations. Limiting behaviours for beams with large (and small) aspect ratios, which can be established using classical plate theories, are recovered from the new governing equation to illustrate its consistency and also to illustrate the importance of using plate theories with the correctly refined boundary conditions. The implications for the correct choice of the shear correction factor in Timoshenko's beam theory are also discussed.

The TLR4 Agonist Immunomax Affects the Phenotype of Mouse Lung Macrophages during Respiratory Syncytial Virus Infection.

In the study, the effect of the TLR4 agonist Immunomax was investigated in vitro and in vivo. In particular, Immunomax was shown to polarize mouse bone marrow macrophages from the M0 and M2 states into the M1 state (ARG1 and iNOS mRNA expression levels were used to identify the mouse M1 and M2 phenotypes). Next, we investigated the prophylactic antiviral effect of Immunomax in both a model of mouse respiratory syncytial virus (RSV) infection and a model of RSV-induced bronchial asthma (BA) exacerbation. In the experiment with RSV-induced BA exacerbation, Immunomax-treated mice were characterized by a significant decrease of the viral load in lung homogenates, an increased amount of M1 macrophages in the lung, a tendency toward Th2-dependent ovalbumin-specific IgG1 antibodies decrease in blood serum, a significant increase in RSV-activated CD4+ T cells secreting IFNγ (Th1 cells), and a simultaneous significant decrease in the amount of CD4+ cells secreting IL-4 (Th2 cells) in the mouse spleen, which were detected by ELISPOT 1.5 months after experiment. These findings suggest that treatment with the TLR4 agonist Immunomax polarizes the immune response towards antiviral Th1 and may be used for short-term antiviral prophylaxis to prevent acute respiratory viral infections in asthmatics.

[A supraorbital trans-eyebrow approach in surgery of chiasmatic-sellar and anterior cranial fossa tumors]. / Supraorbital'nyi transbrovnyi dostup v khirurgii opukholei khiazmal'no-selliarnoi oblasti i perednei cherepnoi iamki.

OBJECTIVE: to analyze 31 resections of chiasmatic-sellar region (CSR) and anterior cranial fossa (ACF) tumors using the supraorbital trans-eyebrow approach (STA). MATERIAL AND METHODS: We analyzed medical histories of 31 patients who underwent tumor resection using STA in the period between October 2013 and April 2017. We analyzed the age and gender of patients, size and location of the tumor, presence of a neurological deficit, vision and olfactory functions before and after surgery, surgery duration, amount of intraoperative blood loss, rate of frontal sinus trephination and nasal liquorrhea, hemorrhagic and ischemic complications after surgery, Simpson grade of tumor resection, patient's condition before and after surgery (Glasgow Outcome Scale and Karnofsky Scale), and degree of patient satisfaction with the cosmetic result of surgery. A total of 26 meningiomas (20 sphenoid plate, tubercle, and diaphragm tumors, 3 lesser sphenoid wing meningiomas, 2 orbital roof tumors, and 1 anterior clinoid process meningioma), 3 frontal lobe gliomas, and 2 pituitary adenomas were resected. RESULTS: In all 31 operations, the approach was adequate and enabled tumor resection without lethal outcomes. The mean surgery duration was 174.6±64.4 min. The mean blood loss was 190±96.6 mL (50-380 mL). After surgery, none of the patients developed motor deficits and new epileptic seizures. Neurological deficit aggravation in the form of impaired vision and mental disorders occurred in 8 (25.8%) patients. Vision impaired in 4 (12.9%) patients, improved in 6 (19.3%) patients, and remained unchanged in 21 (67.7%) patients. An endocrinological deficit in the form of partial hypopituitarism developed in 3 (9.6%) patients; in 4 (12.9%) patients, there were mental disorders that regressed by the end of the first month of therapy. There were no intracerebral and subarachnoid hemorrhages. In 2 (6.4%) patients, small epidural hematomas were diagnosed, which did not require surgical treatment. There were only good outcomes (a GOS score of 4 or 5). After surgery, the median Karnofsky index in the STA group was 90±7. In all 31 (100%) patients, the postoperative wound healed by primary intention, without infectious complications and wound liquorrhea. One (4%) patient developed eyebrow palsy; 3 (12%) patients had hypoesthesia in the supraorbital region. The mean VAS score of patient satisfaction with the cosmetic result was 9.36 (median 10±1). The mean follow-up period was 16.2±13.5 months (2-38 months). CONCLUSION: The STA is adequate for removal of CSR and ACF tumors under proper selection of patients. It provides an adequate view of anatomical structures and enables successful tumor resection through a less traumatic access.

HIV Tat induces a prolonged MYC relocalization next to IGH in circulating B-cells.

With combined antiretroviral therapy (cART), the risk for HIV-infected individuals to develop a non-Hodgkin lymphoma is diminished. However, the incidence of Burkitt lymphoma (BL) remains strikingly elevated. Most BL present a t(8;14) chromosomal translocation which must take place at a time of spatial proximity between the translocation partners. The two partner genes, MYC and IGH, were found colocalized only very rarely in the nuclei of normal peripheral blood B-cells examined using 3D-FISH while circulating B-cells from HIV-infected individuals whose exhibited consistently elevated levels of MYC-IGH colocalization. In vitro, incubating normal B-cells from healthy donors with a transcriptionally active form of the HIV-encoded Tat protein rapidly activated transcription of the nuclease-encoding RAG1 gene. This created DNA damage, including in the MYC gene locus which then moved towards the center of the nucleus where it sustainably colocalized with IGH up to 10-fold more frequently than in controls. In vivo, this could be sufficient to account for the elevated risk of BL-specific chromosomal translocations which would occur following DNA double strand breaks triggered by AID in secondary lymph nodes at the final stage of immunoglobulin gene maturation. New therapeutic attitudes can be envisioned to prevent BL in this high risk group.

Correction: Identification of Novel Pre-Erythrocytic Malaria Antigen Candidates for Combination Vaccines with Circumsporozoite Protein.

[This corrects the article DOI: 10.1371/journal.pone.0159449.].

Systems biology insights into the meaning of the platelet's dual-receptor thrombin signaling.

Essentials Roles of the two thrombin receptors in platelet signaling are poorly understood. Computational systems biology modeling was used together with continuous flow cytometry. Dual-receptor system has wide-range sensitivity to thrombin and optimal response dynamics. Procoagulant platelet formation is determined by donor-specific activities of the two receptors. SUMMARY: Background Activation of human platelets with thrombin proceeds via two protease-activated receptors (PARs), PAR1 and PAR4, that have identical main intracellular signaling responses. Although there is evidence that they have different cleavage/inactivation kinetics (and some secondary variations in signaling), the reason for such redundancy is not clear. Methods We developed a multicompartmental stochastic computational systems biology model of dual-receptor thrombin signaling in platelets to gain insight into the mechanisms and roles of PAR1 and PAR4 functioning. Experiments employing continuous flow cytometry of washed human platelets were used to validate the model and test its predictions. Activity of PAR receptors in donors was evaluated by mRNA measurement and by polymorphism sequencing. Results Although PAR1 activation produced rapid and short-lived response, signaling via PAR4 developed slowly and propagated in time. Response of the dual-receptor system was both rapid and prolonged in time. Inclusion of PAR1/PAR4 heterodimer formation promoted PAR4 signaling in the medium range of thrombin concentration (about 10 nm), with little contribution at high and low thrombin. Different dynamics and dose-dependence of procoagulant platelet formation in healthy donors was associated with individual variations in PAR1 and PAR4 activities and particularly by the Ala120Thr polymorphism in the F2RL3 gene encoding PAR4. Conclusions The dual-receptor combination is critical to produce a response combining three critical advantages: sensitivity to thrombin concentration, rapid onset and steady propagation; specific features of the protease-activated receptors do not allow combination of all three in a single receptor.

Nuclear localization of translocation partners in differentiating B-cells.

We studied the nuclear localization and relative position in the nuclear space of malignant translocation partner genes c-Myc, CCND1, and IGH locus in naive and differentiating B cells. We have shown that, during B-cell maturation, c-Myc and IGH loci become closer to each other. In differentiating lymphocytes, those alleles of c-Myc and IGH that are in close spatial proximity to each other are closer to the nucleolus. For the CCND1 locus, no correlation between the proximity of loci and nuclear localization was found. These data suggest that the close spatial proximity of c-Myc and IGH loci during B-cell maturation increase the probability of malignant translocation.

Monoclonal antibody profiling of cell surface proteins associated with the viral biofilms on HTLV-1 transformed cells.

Human T lymphotropic virus 1 (HTLV-1) is a pathogenic retrovirus that spreads predominantly via cell-to-cell contact. Two models of cell-to-cell virus transmission are proposed: virological synapse (VS) and viral biofilms (VB). Both infectious structures can be involved in transmission and synergistically enhance HTLV-1 spread between cells. Although transmission of virus via VB has been reported, the molecular composition of VB remains poorly understood. In this study we generated new anti-VB monoclonal antibodies (MAbs) and screenedthem along with a panel of anti-human cluster of differentiation (CD) MAbs to select antigens associated with VB. Among four MAbs generated against VB, two MAbs were identified as anti-CD25 (IL-2RA). We found that antigens CD4, CD150, CD25, CD70, and CD80 were enriched in VB. We also determined that expression of viral protein Tax, a central molecule in HTLV-1 transmission, upregulates intercellular adhesion molecule 1 (ICAM-1), CD95, CD25, CD70, and CD80. Whether these antigens are essential for VB formation and HTLV-1 infection remains unknown and will be determined in further experiments.

Regulation of the target protein (transgene) expression in the adenovirus vector using agonists of toll-like receptors.

Replication-defective adenoviral vectors are effective molecular tools for both gene therapy and gene vaccination. Using such vectors one can deliver and express target genes in different epithelial, liver, hematopoietic and immune system cells of animal and human origin. The success of gene therapy and gene vaccination depends on the production intensity of the target protein encoded by the transgene. In this work, we studied influence of Toll-like receptors (TLR) agonists on transduction and expression efficacy of adenoviral vectors in animal and human antigen-presenting cells. We found that agonists of TLR2, 4, 5, 7, 8 and 9 significantly enhance a production of the target protein in cells transduced with adenoviral vector having the target gene insert. The enhancement was observed in dendritic cells and macrophages expressing cytoplasmic (GFP), membrane (HA) or secretory (SEAP) proteins encoded by the respective rAd-vectors. Experiments in mice showed that enhancement of the transgene expression can be achieved in the organism of animals using a pharmaceutical-grade TLR4-agonist. In contrast to other TLR-agonists, the agonist of TLR3 substantially suppressed the expression of transgene in cells transduced with adenoviral vectors having insert of GFP or SEAP target genes. We propose that the enhancement of transgene expression is linked to the activation of MyD88→ NF-kB, while the inhibition of transgene expression depends on TRIF→ IRF signaling pathways. Both of these pathways jointly exploited by TLR4-agonists lead to the enhancement of transgene expression due to the dominant role of the MyD88→ NF-kB signaling.

[Comparative analysis of the immune response to DNA constructions encoding hepatitis C virus nonstructural proteins].

A promising approach to construction of antiviral vaccines consists in activation of cellular immunity with the DNA vaccines. The goal of this work was to evaluate the efficacy of genetic immunization of mice with DNA pcNS3-NS5B encoding five hepatitis C virus (HCV) nonstructural proteins: NS3, NS4A, NS4B, NS5A, and NS5B in comparison with plasmids containing genes of same individual nonstructural proteins. The DNA constructions were injected intramuscularly in DBA mice three times. The humoral immune response was assessed with ELISA; cellular immune response--in blast transformation reaction, by quantitation of CD4+ and CD8+ T cell proliferation using flow cytofluorometry, by intracellular synthesis and secretion of IFN-gamma and IL-2 in ELISpot and ELISA. It was found that the functionally active T cell response was achieved to antigens presenting NS3, NS4, NS5A, and NS5B epitopes of different HCV genotypes in response to pcNS3-NS5B plasmid and was stronger than that to plasmids carrying individual genes. A high proliferation rate of CD4+ T cells, secretion of IL-2 and IFN-gamma, induction of anti-NS3 and anti-NS5B IgG2a were demonstrated. These findings indicate that DNA construction pcNS3-NS5B is one of promising candidates for anti-HCV vaccine developing.

Transcription factories in the context of the nuclear and genome organization.

In the eukaryotic nucleus, genes are transcribed in transcription factories. In the present review, we re-evaluate the models of transcription factories in the light of recent and older data. Based on this analysis, we propose that transcription factories result from the aggregation of RNA polymerase II-containing pre-initiation complexes assembled next to each other in the nuclear space. Such an aggregation can be triggered by the phosphorylation of the C-terminal domain of RNA polymerase II molecules and their interaction with various transcription factors. Individual transcription factories would thus incorporate tissue-specific, co-regulated as well as housekeeping genes based only on their initial proximity to each other in the nuclear space. Targeting genes to be transcribed to protein-dense factories that contain all factors necessary for transcription initiation and elongation through chromatin templates clearly favors a more economical utilization and better recycling of the transcription machinery.

["Low infusion resuscitation" in the treatment of wounded and injured with acute massive blood loss].

Acute massive blood loss (AMBL) of severe and extremely severe degree is still one of the leading causes of unfavourable traumatic disease. 95% of potentially preventable lethal outcomes in severe gunshot trauma is reported to depend largely on the adequacy of AMBL correction (Howard P., 2003). An alternate approach to the issue studied was the development of preparations of hyperosmotic saline solutions (7.5% sodium chloride) combined with hyperoncotic colloid solutions (dextrans, hetastarch). As a result, solutions were developed (so-called, hyperosmotic hyperoncotic volume expanders) allowing to achieve rapid and stable volemic and hemodynamic effect in case of low volume infusion (usually, 4 ml/kg of body weight). The present study allowed to conclude that "low infusion resuscitation" technique in patients with multiple trauma accompanied by acute massive blood loss of extremely severe degree enables to reduce lethality, to achieve early subcompesatory hemodynamic state in acute traumatic disease.

[Postinfection irritable bowel syndrome].

AIM: To characterize pathogenesis, clinicolaboratory criteria and treatment of postinfection irritable bowel syndrome (PICS). MATERIAL AND METHODS: The examination including histological study of the small and large intestine mucosa, polymerase chain reaction (PCR), coagglutination reaction using shigella, salmonella, yersinia, campilobacter jejuni diagnosticums, indirect hemagglutination reaction for identification of antibodies to these agents in the blood serum was conducted in 750 patients with PICS. Fecal seeding on selective media was made as well as the respiratory test for bacterial growth in the small intestine. Immune status was studied with laser cytometry, chemiluminescence, immunodiffusion, immunofluorescence, flow laser cytofluorometry. Personality profile was assessed by MMPI. RESULTS: PICS was diagnosed in 599 (79.9%) of 750 patients. Most of them had diarrhea, abnormal fecal microflora, antigens of acute intestinal infection agents in circulating immune complexes of the serum and coprofiltrates. Immune system was characterized by low phagocytic activity, attenuation of cell and humoral immunity. Etiotropic and pathogenetic treatment including intestinal antiseptics, probiotics and immunomodulators produced persistent remission during a year in 79.3% PICS patients. CONCLUSION: PICS is described which differs from ICS by registration of markers of acute intestinal infections in biological media, bacterial overgrowth in the small intestine and dysbiosis in the large intestine, immunodeficiency. A positive response was observed to treatment with intestinal antiseptic and enterosorbent drugs, probiotics and immunomodulators.

Lung carcinogenesis induced by chronic tuberculosis infection: the experimental model and genetic control.

Coexistence of pulmonary tuberculosis (TB) and lung cancer in clinic poses significant challenges for the diagnostic and treatment of both diseases. Although association of chronic inflammation and cancer is well-documented, causal relationship between TB infection and lung cancer are not understood. We present experimental evidence that chronic TB infection induces cell dysplasia and squamous cell carcinoma (SCC) in a lung-specific manner. First, squamous cell aggregates consistently appeared within the lung tissue associated with chronic TB lesions, and in some cases resembled SCCs. A transplantable tumor was established after the transfer of cells isolated from TB lung lesions into syngeneic recipients. Second, the (Mycobacterium tuberculosis) MTB-infected macrophages play a pivotal role in TB-induced carcinogenesis by inducing DNA damage in their vicinity and by the production of a potent epidermal growth factor epiregulin, which may serve as a paracrine survival and growth factor responsible for squamous metaplasia and tumorigenesis. Third, lung carcinogenesis during the course of chronic TB infection was more pronounced in animals with severe lung tissue damage mediated by TB-susceptibility locus sst1. Together, our experimental findings showed a causal link between pulmonary TB and lung tumorigenesis and established a genetic model for further analysis of carcinogenic mechanisms activated by TB infection.

Extensional edge modes in elastic plates and shells.

The recently discovered undamped localized mode at the end of an elastic strip is demonstrated to be particularly relevant in the plane stress setting, where it exists for the Poisson ratio 0.29. This paper also emphasizes the difference between low-frequency edge modes, typically characterized by low variation across the plate (or shell) thickness, and high-frequency edge modes, whose natural frequencies are of the order of thickness resonance frequencies.

Multigenic control of tuberculosis resistance: analysis of a QTL on mouse chromosome 7 and its synergism with sst1.

Tuberculosis remains a significant global health problem: one-third of the human population is infected with Mycobacterium tuberculosis (MTB) and 10% of those are at lifetime risk of developing tuberculosis. In the majority of individuals infected, genetic determinants of susceptibility remain largely unknown due to complex multigenic control and the influence of genes--environment interactions. Genetic variation of host resistance to MTB in animal models reflects heterogeneity among humans. Stepwise dissection of these interactions will permit the deciphering of MTB's complex virulence strategy. Previously, we have characterized a mouse supersusceptibility locus (sst1) controlling antituberculosis immunity. In this study, eight host resistance quantitative trait loci (QTLs) were mapped that counter-balance the devastating effect of sst1, among which a QTL on chromosome 7 (Chr7) was most prominent. The Chr7 and sst1 loci independently control distinct resistance mechanisms to MTB, but their effects apparently converge on macrophages in remarkable synergy. Combining these resistance alleles on a C3HeB/FeJ-susceptible background reduced the lung pathology and improved survival after MTB challenge accounting for half of the difference between susceptible and resistant parental strains. These data reveal novel gene interactions controlling MTB resistance and will enable the identification of resistance gene(s) encoded within Chr7 locus.

I/St mice hypersusceptible to Mycobacterium tuberculosis are resistant to M. avium.

We previously demonstrated that mice of the I/St strain are extremely susceptible to Mycobacterium tuberculosis, as well as to the taxonomically distant intracellular bacteria Chlamydia pneumoniae and Salmonella enterica. To broaden our knowledge about the control of susceptibility to intracellular pathogens, we studied the infection caused by Mycobacterium avium virulent strain 724 in a panel of inbred mouse strains and found that I/St mice are resistant to M. avium. By comparing I/St mice with B6 mice, we demonstrated that (i) B6 mice are much more susceptible to infection caused by M. avium in terms of bacterial multiplication in the lung tissue and severity of lung pathology; (ii) in B6 mice but not in I/St mice infection leads to prolonged leukocyte infiltration of the lung tissue, development of necrotic lung granulomata, and lethality; and (iii) the unfavorable infectious course in B6 mice is accompanied by elevated production of gamma interferon, tumor necrosis factor alpha, and especially interleukin-12 in the lungs. Importantly, M. avium-resistant I/St mice carry a functional r allele of the Slc11a1 (formerly Nramp1) gene, while B6 mice have the Slc11a1(s) genotype. Segregation genetic analysis of (I/St x B6) F2 hybrids demonstrated that susceptibility or resistance to infection caused by M. avium largely depended upon the Slc11a1 genotype and that other genetic traits had a relatively weak influence. This close-to-monogenic pattern differs sharply from the host control of many other intracellular bacterial infections, for which the involvement of numerous quantitative trait loci has been ubiquitously observed.