Reactivation of Latent Tuberculosis: Variations on the Cornell Murine Model

Mycobacterium tuberculosis causes active tuberculosis in only a small percentage of infected persons. In most cases, the infection is clinically latent, although immunosuppression can cause reactivation of a latent M. tuberculosis infection. Surprisingly little is known about the biology of the bacterium or the host during latency, and experimental studies on latent tuberculosis suffer from a lack of appropriate animal models. The Cornell model is a historical murine model of latent tuberculosis, in which mice infected with M. tuberculosis are treated with antibiotics (isoniazid and pyrazinamide), resulting in no detectable bacilli by organ culture. Reactivation of infection during this culture-negative state occurred spontaneously and following immunosuppression. In the present study, three variants of the Cornell model were evaluated for their utility in studies of latent and reactivated tuberculosis. The antibiotic regimen, inoculating dose, and antibiotic-free rest period prior to immunosuppression were varied. A variety of immunosuppressive agents, based on immunologic factors known to be important to control of acute infection, were used in attempts to reactivate the infection. Although reactivation of latent infection was observed in all three variants, these models were associated with characteristics that limit their experimental utility, including spontaneous reactivation, difficulties in inducing reactivation, and the generation of altered bacilli. The results from these studies demonstrate that the outcome of Cornell model-based studies depends critically upon the parameters used to establish the model.     

Quantitative Comparison of Active and Latent Tuberculosis in the Cynomolgus Macaque Model

We previously described that low-dose Mycobacterium tuberculosis infection in cynomolgus macaques results in a spectrum of disease similar to that of human infection: primary disease, latent infection, and reactivation tuberculosis (S. V. Capuano III, D. A. Croix, S. Pawar, A. Zinovik, A. Myers, P. L. Lin, S. Bissel, C. Fuhrman, E. Klein, and J. L. Flynn, Infect. Immun. 71:5831-5844, 2003). This is the only established model of latent infection, and it provides a unique opportunity to understand host and pathogen differences across of range of disease states. Here, we provide a more extensive and detailed characterization of the gross pathology, microscopic histopathology, and immunologic characteristics of monkeys in each clinical disease category. The data underscore the similarities between human and nonhuman primate M. tuberculosis infection. Furthermore, we describe novel methods of quantifying gross pathology and bacterial burden that distinguish between active disease and latent infection, and we extend the usefulness of this model for comparative studies. Early in infection, an abnormal chest X ray, M. tuberculosis growth by gastric aspirate, and increased mycobacterium-specific gamma interferon (IFN-γ) in peripheral blood mononuclear cells (PBMCs) and bronchoalveolar lavage (BAL) cells were associated with the development of active disease. At necropsy, disease was quantified with respect to pathology and bacterial numbers. Microscopically, a spectrum of granuloma types are seen and differ with disease type. At necropsy, monkeys with active disease had more lung T cells and more IFN-γ from PBMC, BAL, and mediastinal lymph nodes than monkeys with latent infection. Finally, we have observed a spectrum of disease not only in monkeys with active disease but also in those with latent infection that provides insight into human latent tuberculosis.Mycobacterium tuberculosis is a remarkably successful human pathogen. Infection, usually via the respiratory route, results in primary tuberculosis or latent infection. Primary tuberculosis, defined as active disease within 2 years of the initial infection, is likely the result of a failure of the host immune response to control the infection. In this case, the initial infection can progress rapidly or slowly but causes contagious, active tuberculosis. Primary disease occurs in ∼5 to 10% of infected individuals (30). In contrast, most persons control the initial infection but apparently do not eliminate the bacteria completely. This asymptomatic condition is termed latent infection and is not considered to be contagious. A small percentage (5 to 10%) of latently infected persons reactivate during the course of a lifetime, resulting in active disease (reactivation). In humans, reactivation rates are increased in the setting of immune suppression, including human immunodeficiency virus (HIV) coinfection (30), aging (34), and tumor necrosis factor (TNF) neutralization (15, 24).The factors that dictate the outcome of M. tuberculosis infection in humans are not well understood. Studies of murine models have identified T cells, particularly CD4 T cells, as important in the control of initial and chronic infection. The cytokines gamma interferon (IFN-γ), interleukin-12 (IL-12), and TNF also have been shown to be crucial for the control of infection. IFN-γ is necessary for the activation of macrophages, and TNF has multiple functions in the immune response to M. tuberculosis (reviewed in reference 6). This is recapitulated in human studies, in which TNF neutralization (15, 24) and HIV infection (either as the direct loss of CD4 T cells or another immunologic perturbation) (30) has been associated with increased susceptibility to tuberculosis.Although the mouse model has been instrumental in defining several important aspects of the immune response to M. tuberculosis, infection in the mouse is progressive and ultimately leads to death. Mice control initial infection and a state of chronic infection ensues that is characterized by slowly advancing pathology, although the progression of disease is determined in part by the mouse strain used and the inoculating dose. Regardless, the mouse is not a model of latent infection. Mice also lack the organizational characteristics of human granulomas and do not have hypoxic granulomas, which are seen in humans and our model (32). Human granulomas have much more structured architecture, often with caseous necrosis in the center, and can be surrounded by a peripheral rim of fibrosis. Other animal models can display more human-like granulomas, such as the guinea pig and the rabbit, but latent infection has not been demonstrated in either of these animal models and immunology tools are limited.We previously reported that cynomolgus macaques infected with a low dose of M. tuberculosis either develop primary tuberculosis or have latent infection (3). To validate our clinical classification of disease states and quantify the outcome of infection, here we perform an in-depth comparison of monkeys with active and latent disease, and we demonstrate significant differences between these two clinically determined infection states with respect to gross and microscopic histopathology, bacterial numbers, and immune responses. There is a spectrum of disease in active tuberculosis and also in the subclinical state that is classified as latent infection. This is an effective model for understanding the events that predict disease outcome and for investigating therapies for active and latent tuberculosis and reactivation from latent infection. The close similarities between human and nonhuman primates with M. tuberculosis infection provide an excellent model for the study of tuberculosis. We demonstrate here that the outcomes of infection and amount of disease now can be quantified, allowing an analysis of monkey groups that will be useful when using this model to study immune interventions or drugs.     

Rv1813c在结核分枝杆菌潜伏感染诊断中的价值

目的 研究重组结核分枝杆菌潜伏感染蛋白Rv1813c在诊断结核分枝杆菌潜伏感染方面的价值.方法 20例结核潜伏感染者和79例健康志愿者均行胸部X线检查、PPD皮肤试验、结核抗体检测,同时应用ELISA联合重组融合蛋白CFP10-ESAT6和潜伏感染蛋白Rv1813c进行IGRA检测.结果 所有受试者中,PPD皮肤试验和抗体检测的阳性率分别为50％和28％.Rv1813c刺激潜伏感染者后产生IFN-γ的水平显著高于健康对照(P＜0.05),其刺激PPD强阳性组(皮试直径≥15mm)产生的IFN-γ值低于弱阳性组(5mm≤皮试直径＜15mm),但无统计学意义,而CFP10-ESAT6刺激PPD强阳性组后产生的IFN-γ值高于弱阳性组(P＜0.05).CFP10-ESAT6和Rv1813c刺激抗体阴性及阳性组后产生的IFN-γ水平没有显著性差异(P＞0.05).Rv1813c诊断结核感染的ROC曲线下面积为0.834,特异性80％时,灵敏度为85％;特异性为90％时,灵敏度为45％.结论 同时检测Rv1813c及CFP10-ESAT6抗原特异的IFN-γ值有可能筛选出潜伏感染者中的活动感染人群,对于结核分枝杆菌潜伏感染诊断有重要的应用价值.     

Immunotherapeutical Potential of Mycobacterium Vaccae on M. Tuberculosis Infection in Mice

Tuberculosis remains the worldwide infectious disease. To identify the therapeutic potential of M. vaccae in treating tuberculosis, M. vaccae was injected into Mycobacterium tuberculosis （M. tuberculosis） infected mice. The optimal dose of M. vaccae （22.5 μg/mouse） treated mice showed lower pathological change index, spleen weight index, lung weight index and vital M. tuberculosis count than those of the untreated group. Treatment with M. vaccae enhanced the percentages of CD3^＋ and CD4^＋ T cells, IFN-γ^＋CD4^＋ T cells, innate immune cells including NK cells, NK1.1^＋ T cells and γδ T cells, and reduced the percentage of IL-4^＋CD4^＋ T cells. Therefore, M. vaccae could protect the mice from M. tuberculosis infection and improved mouse innate and adaptive cell-mediated immunity, suggesting that M. vaccae is a potential immunotherapeutic agent in pulmonary tuberculosis. Cellular ＆ Molecular Immunology.     

Coexistent Malnutrition Is Associated with Perturbations in Systemic and Antigen-Specific Cytokine Responses in Latent Tuberculosis Infection

Malnutrition, as defined by low body mass index (BMI), is a major risk factor for the development of active tuberculosis (TB), although the biological basis underlying this susceptibility remains poorly characterized. To verify whether malnutrition affects the systemic and antigen-specific cytokine levels in individuals with latent TB (LTB), we examined circulating and TB antigen-stimulated levels of cytokines in individuals with LTB and low BMI (LBMI) and compared them with those in individuals with LTB and normal BMI (NBMI). Coexistent LBMI with LTB was characterized by diminished circulating levels of type 1 (gamma interferon [IFN-γ] and tumor necrosis factor alpha [TNF-α]), type 2 (interleukin-4 [IL-4]), type 17 (IL-22), and other proinflammatory (IL-1α, IL-1β, and IL-6) cytokines but elevated levels of other type 2 (IL-5 and IL-13) and regulatory (IL-10 and transforming growth factor beta [TGF-β]) cytokines. In addition, LBMI with LTB was associated with diminished TB antigen-induced IFN-γ, TNF-α, IL-6, IL-1α, and IL-1β levels. Finally, there was a significant positive correlation between BMI values and TNF-α and IL-1β levels and a significant negative correlation between BMI values and IL-2, IL-10, and TGF-β levels in individuals with LTB. Therefore, our data reveal that latent TB with a coexistent low BMI is characterized by diminished protective cytokine responses and heightened regulatory cytokine responses, providing a potential biological mechanism for the increased risk of developing active TB.     

Lack of Response to HBHA in HIV‐Infected Patients with Latent Tuberculosis Infection

Heparin‐binding haemagglutinin (HBHA) has been proposed as an immunological biomarker for discriminating active tuberculosis (TB) from latent TB infection (LTBI) and to identify those at higher risk of progressing to active disease. Few data are available in immune‐compromised patients, which are those with increased risk of TB reactivation. The aim of this stusy was to evaluate the immune response to HBHA in HIV‐infected subjects with LTBI (HIV‐LTBI) or active TB (HIV‐TB) in comparison with the immune response to additional Mycobacterium tuberculosis (Mtb) or HIV and CMV antigens. The responses are evaluated in relation to TB status and in the LTBI subjects with the progression to active TB within 2 years. Forty‐one HIV‐infected antiretroviral‐naïve subjects were prospectively enrolled: 18 were HIV‐TB and 23 HIV‐LTBI. Whole blood was in vitro stimulated overnight with several antigens and mitogen. Interferon‐γ response in the harvested plasma was evaluated by ELISA. Despite that CD4 cell count was significantly different between HIV‐LTBI and HIV‐TB, no differences were observed in response to Mtb‐ or HIV‐specific antigens. Differently, low responses to HBHA were observed in both HIV‐LTBI and HIV‐TB subjects. Importantly, none of the six HIV‐LTBI responding to HBHA developed TB, while two of 17 non‐HBHA responders developed active disease. HIV‐TB‐coinfected subjects, regardless of their TB status, showed low responses to HBHA despite maintaining detectable responses to other antigens; moreover, among the HIV‐LTBI, the lack of HBHA responses indicated an increased risk to develop active TB. These results, although preliminary, suggest that a positive response to HBHA in HIV‐LTBI correlates with Mtb containment.     

Virulence and Immune Response Induced by Mycobacterium avium Complex Strains in a Model of Progressive Pulmonary Tuberculosis and Subcutaneous Infection in BALB/c Mice

The genus Mycobacterium comprises more than 150 species, including important pathogens for humans which cause major public health problems. The vast majority of efforts to understand the genus have been addressed in studies with Mycobacterium tuberculosis. The biological differentiation between M. tuberculosis and nontuberculous mycobacteria (NTM) is important because there are distinctions in the sources of infection, treatments, and the course of disease. Likewise, the importance of studying NTM is not only due to its clinical significance but also due to the mechanisms by which some species are pathogenic while others are not. Mycobacterium avium complex (MAC) is the most important group of NTM opportunistic pathogens, since it is the second largest medical complex in the genus after the M. tuberculosis complex. Here, we evaluated the virulence and immune response of M. avium subsp. avium and Mycobacterium colombiense, using experimental models of progressive pulmonary tuberculosis and subcutaneous infection in BALB/c mice. Mice infected intratracheally with a high dose of MAC strains showed high expression of tumor necrosis factor alpha (TNF-α) and inducible nitric oxide synthase with rapid bacillus elimination and numerous granulomas, but without lung consolidation during late infection in coexistence with high expression of anti-inflammatory cytokines. In contrast, subcutaneous infection showed high production of the proinflammatory cytokines TNF-α and gamma interferon with relatively low production of anti-inflammatory cytokines such as interleukin-10 (IL-10) or IL-4, which efficiently eliminate the bacilli but maintain extensive inflammation and fibrosis. Thus, MAC infection evokes different immune and inflammatory responses depending on the MAC species and affected tissue.     

Development and Characterization of a Staphylococcus aureus Nasal Colonization Model in Mice

Staphylococcus aureus nasal carriage is a risk factor for infection in humans, particularly in the hospital environment. Attenuation of carriage has proven effective in reducing the prevalence of infection in some high-risk groups. To study staphylococcal factors that influence nasal colonization, a mouse model of S. aureus nasal colonization was developed. Mice were inoculated intranasally with S. aureus Reynolds, and nasal carriage was evaluated by quantitating cultures of the nasal tissues from mice sacrificed at various time points after inoculation. The majority of mice inoculated with 10(8) CFU of S. aureus maintained nasal carriage for at least 20 days. Nasal colonization rates were similar for inbred (BALB/c and C57BL/6) and outbred (ICR) mice. Colonization was not affected by mouse passage of strain Reynolds. Lower inoculum doses (<10(7) CFU) resulted in reduced colonization after 7 days. However, mice given streptomycin in their drinking water developed long-term carriage of S. aureus, and they were colonized with inocula as low as 10(5) CFU. Nasal colonization was also established with two other S. aureus strains (one strain each of human and murine origins). S. aureus recovered from the nares of experimentally colonized mice expressed high levels of capsule, and the ability of a capsule-defective mutant to persist in the nares was reduced in comparison to that of the parent strain. This nasal colonization model should prove useful for studies of factors that mediate S. aureus colonization and for assessment of targets for antimicrobial intervention or vaccine development.     

Acute Morphine Administration Reduces Cell-Mediated Immunity and Induces Reactivation of Latent Herpes Simplex Virus Type 1 in BALB/c Mice

Acute morphine administration is known to alter the course of herpes simplex virus infection. In this study, the effect of acute morphine administration on the reactivation of latent herpes was investigated in a mouse model. Because of the important role of cytolytic T lymphocyte （CTL） activity in the inhibition of herpes simplex virus type 1 （HSV-1） reactivation, the effect of acute morphine administration on CTL responses was also evaluated. Furthermore, lymphocyte proliferation and IFN-γ production were evaluated for their roles in the induction of the CTL response. The findings showed that acute morphine administration significantly reduced CTL responses, lymphocyte proliferation, and IFN-γ production. Furthermore, acute morphine administration has been shown to reactivate latent HSV-γ. Previous studies have shown that cellular immune responses have important roles in the inhibition of HSV reactivation. These findings suggest that suppression of a portion of the cellular immune response after acute morphine administration may constitute one part of the mechanism that induces HSV reactivation.     

Novel Immunoblot Assay Using Four Recombinant Antigens for Diagnosis of Epstein-Barr Virus Primary Infection and Reactivation

A new immunoblot assay, composed of four Epstein-Barr virus (EBV)-encoded recombinant proteins (virus capsid antigen [VCA] p23, early antigen [EA] p138, EA p54, and EBNA-1 p72), was compared with an immunofluorescence assay on a total of 291 sera. The test was accurate in 94.5% of cases of primary EBV infection, while an immunoglobulin G anti-VCA p23 band with strong intensity correlated with reactivation.     

Animal Model of Mycoplasma pneumoniae Infection Using Germfree Mice

We have attempted to establish a gnotobiotic mouse model monoassociated with Mycoplasma pneumoniae following single or repeated infection to examine the mechanism of pathogenesis following M. pneumoniae infection. M. pneumoniae inoculated into germfree mice colonized equally well at 10⁵ CFU/lung in both single infection and repeated infection. In histopathological observation, repeatedly infected mice showed pneumonia with mild infiltration of mononuclear cells and macrophages. Antibody titers against M. pneumoniae rose in the repeatedly infected mice but not in the singly infected mice. The percentage of CD4-positive, CD8-positive, and CD25-positive lymphocytes infiltrated in the lung was increased in the repeatedly infected mice. In contrast, the lymphocyte subset in the spleen was not significantly different among mock-, singly, and repeatedly infected mice. In the study of cytokine productivity of spleen cells, production of interleukin (IL)-4 and IL-10 was significantly increased and that of gamma interferon was remarkably increased in the mice following repeated infection. These results indicate that a gnotobiotic mouse model monoassociated with M. pneumoniae was established and that immune mechanisms might be involved in the pathogenesis in pneumonia following M. pneumoniae infection.     

Dominant Role of the sst1 Locus in Pathogenesis of Necrotizing Lung Granulomas during Chronic Tuberculosis Infection and Reactivation in Genetically Resistant Hosts

Significant host heterogeneity in susceptibility to tuberculosis exists both between and within mammalian species. Using a mouse model of infection with virulent Mycobacterium tuberculosis (Mtb), we identified the genetic locus sst1 that controls the progression of pulmonary tuberculosis in immunocompetent hosts. In this study, we demonstrate that within the complex, multigenic architecture of tuberculosis susceptibility, sst1 functions to control necrosis within tuberculosis lesions in the lungs; this lung-specific sst1 effect is independent of both the route of infection and genetic background of the host. Moreover, sst1-dependent necrosis was observed at low bacterial loads in the lungs during reactivation of the disease after termination of anti-tuberculosis drug therapy. We demonstrate that in sst1-susceptible hosts, nonlinked host resistance loci control both lung inflammation and production of inflammatory mediators by Mtb-infected macrophages. Although interactions of the sst1-susceptible allele with genetic modifiers determine the type of the pulmonary disease progression, other resistance loci do not abolish lung necrosis, which is, therefore, the core sst1-dependent phenotype. Sst1-susceptible mice from tuberculosis-resistant and -susceptible genetic backgrounds reproduce a clinical spectrum of pulmonary tuberculosis and may be used to more accurately predict the efficacy of anti-tuberculosis interventions in genetically heterogeneous human populations.Tuberculosis remains a global epidemic, with one-third of the population infected, 9 million new active cases, and almost 2 million deaths each year.¹ Existing anti-tuberculosis vaccines (BCG) and drugs have proven insufficient for global control of the disease. Many investigators are working to develop novel, more efficient interventions based on animal models that recapitulate key aspects of the human disease. For tuberculosis, however, which animal model better suits this purpose remains controversial.^2,3Mouse models have played a key role in identification of essential mechanisms of host resistance to mycobacterial infections.^4,5,6 However, how closely the mouse disease resembles critical aspects of pulmonary tuberculosis in tuberculosis-susceptible, but immunocompetent humans, has been less clear. On the one hand, tuberculosis infection in immunocompetent inbred mouse strains, as in humans, predominantly targets the lungs.⁶ On the other hand, typical mouse lesions described in the literature lack central necrosis, a characteristic and defining feature of well-organized tuberculosis lesions in immunocompetent humans. Importantly, tuberculosis lung lesions in standard mouse strain are significantly less hypoxic than human granulomas.^2,3,7 These differences in lesion environment are likely to induce dissimilar functional states of the bacteria in human and mouse lungs. This raises the concern that the efficacy of anti-tuberculosis vaccines, immunomodulators, or drug combinations determined using experimental mouse models may not foretell success in human populations.This skepticism regarding the generic mouse model of tuberculosis is based on the analysis of granuloma pathobiology in a very limited set of mouse strains. Meanwhile, similar to humans and other mammalian species, there is broad variation in tuberculosis susceptibility among laboratory mouse strains,⁵ although the development of well-structured pulmonary granulomas has not been described until recently. The C3HeB/FeJ substrain of the standard inbred mouse strain C3H offers a rare, possibly unique phenotype: although immunocompetent, these mice nevertheless develop large necrotic lesions in the lungs, after either systemic intravenous or aerosol infections with virulent Mycobacterium tuberculosis.^8,9 The C3HeB/FeJ lung lesions bear remarkable similarity to tuberculosis lesions in the lungs of susceptible human patients, nonhuman primates, rabbits, and guinea pigs.¹⁰ This allows use of the many tools and reagents available for mice to conduct in-depth immunological and genetic analysis of mechanisms underlying necrosis in lung lesions—a key element of M. tuberculosis virulence.^11,12,13,14Previously, we used forward genetic analysis of a cross of B6 (resistant) and C3HeB/FeJ (susceptible) inbred mouse strains to define the polygenic control of tuberculosis resistance in this model.⁸ We have found that the B6 mice carry four major resistant alleles of quantitative trait loci mapped to mouse chromosomes 1, 7, 15, and 17 (overlapping with the H2 locus) and one susceptibility allele on chromosome 12.^9,15 The chromosome 1 locus sst1 (for supersusceptibility to tuberculosis 1) had an early effect on tuberculosis progression: ∼80% of mice homozygous for the C3H-derived susceptible allele of the sst1 locus succumbed to tuberculosis infection within the first 4 to 7 weeks.⁹ Their early death correlated with the formation of lung necrotic lesions typical for the parental C3HeB/FeJ strain. Transfer of the B6-derived resistant allele of the sst1 locus onto a C3H-susceptible background prevented necrosis formation and increased the survival of the sst1-resistant congenic C3H.B6-sst1 mice to 10 to 12 weeks.⁹ In contrast, resistance loci on chromosomes 7 and 15 did not prevent lung necrosis.¹⁶ We hypothesized that formation of necrosis within tuberculosis lung lesions is a specific effect of the C3HeB/FeJ-derived susceptible allele of the sst1 locus, a postulate tested in the experiments reported here.In multigenic traits, phenotypic expression of individual quantitative trait loci may be significantly affected by genetic background and even disappear as a result of compensatory genetic interactions.¹⁷ Meanwhile the most consistent manifestation of the genetic locus, independent of the genetic background, will most likely reveal its fundamental role. Using novel congenic mice (B6.C3H-sst1), we tested the effect of the susceptible allele of the sst1 locus on tuberculosis progression in a genetically resistant background. This genetic background modified the sst1-mediated phenotype in a quantitative manner, but even in the presence of the resistance alleles on chromosomes 7, 15, and 17, the sst1 locus controlled formation of necrosis within tuberculosis lung lesions. This effect was lung-specific, but independent of a route of infection, systemic or pulmonary. Moreover the sst1-dependent necrosis was observed in the lungs at low bacterial loads after anti-tuberculosis drug therapy predisposing to pulmonary reactivation.     

Orofacial Herpes Simplex Virus Infection in Hairless Mice: Latent Virus in Trigeminal Ganglia After Topical Antiviral Treatment

Inoculation of herpes simplex virus on the forehead and/or snout of hairless mice resulted in a significantly lower mortality rate than inoculation of the skin in the lumbosacral area. Latent herpes simplex virus infections were detected in all forehead-inoculated and in 90% of snout-inoculated mice. Phosphonoacetic acid was highly effective in preventing the development of skin lesions, and no latent infections were detected when phosphonoacetic acid ointment was applied 3 h after infection. Neither adenine arabinoside nor adenine arabinoside monophosphate prevented the establishment of latent infections in the trigeminal ganglia, although they protected the mice from the fatal outcome of the infection. The antibody response after adenine arabinoside or adenine arabinoside monophosphate treatment was similar to that observed in untreated animals, and it was six to eight times higher than in mice treated with phosphonoacetic acid. Mice without evidence of latent infection had, in general, lower serum antibody titers than those with latent infections in the ganglia. An analysis of the pathogenesis of herpes simplex virus infection in mice treated with adenine arabinoside showed that virus penetration into the nerve endings was delayed and that the amount of free virus in ganglionic homogenates was 10 to 100 times less than that for untreated mice.     

Immunological Characterization of Human Vaginal Xenografts in Immunocompromised Mice : Development of a Small Animal Model for the Study of Human Immunodeficiency Virus-1 Infection

A small animal model for the in vivo study of human immunodeficiency virus-1 and other fastidious infectious agents in human host target tissues is critical for the advancement of therapeutic and preventative strategies. Our laboratory has developed a human vaginal xenograft model that histologically recapitulates features of the human vaginal epithelial barrier. Vaginal xenografts were surgically implanted into C.B.-Igh-1(b)/IcrTac-Prkdc(scid) (SCID) and NOD/LtSz-scid/scid (NOD/SCID) mice, with and without human peripheral blood mononuclear cell reconstitution. Immunohistochemical staining of vaginal xenografts demonstrated that in the SCID strain healed vaginal xenografts did not retain intrinsic human immune cells at baseline levels, whereas the NOD/SCID strain supported retention of intrinsic human immune cell populations within the xenografts for at least 2 months after engraftment. In peripheral blood mononuclear cell-reconstituted NOD/SCID mice with vaginal xenografts, flow cytometric analyses detected human immune cell populations in the peripheral blood and immunohistochemical methods detected infiltration of human CD45+ cells in the mouse spleens and vaginal xenografts for at least 2 months after reconstitution. This optimized NOD/SCID human vaginal xenograft model may provide a unique small animal in vivo system for the study of human immunodeficiency virus-1 transmission and infection.     

新型双光子荧光染料DMAHAS在人-鼠肝癌模型中的应用

研究一种新型双光子荧光素（DMAHAS）对人肝癌HepG2细胞的毒性及肿瘤细胞标记后的体内示踪。体外细胞毒性分析采用MTT、中性红（NR）、考马斯亮蓝（CB）和流式细胞术（FCM）等方法。DMAHAS标记肿瘤细胞的体内示踪在人肝癌模型中进行,切除的肿瘤异种移植物经荧光成像和传统的组织病理分析。此外,我们建立了一种基于DMAHAS释放的细胞毒性分析方法。研究结果表明DMAHAS对HepG2细胞无明显毒性,它显示出对活细胞很高的穿透性和稳定的细胞质定位。体内细胞示踪实验表明它是一种用于肿瘤示踪和荧光成像的可靠探针。     

Latent Tuberculosis Infection Screening and Treatment in Congregate Settings (TB FREE COREA): Demographic Profiles of Interferon-Gamma Release Assay Cohort

In 2017, the Korean government launched an unprecedentedly large-scaled latent tuberculosis infection (LTBI) screening project which covered more than a million individuals in congregate settings. A total of 1,047,689 participants of source population (n = 2,336,157) underwent LTBI testing from 2017 to 2018. The overall LTBI test uptake rate during this project was 44.8%. Workers in daycare centers (83.5%) and kindergartens (78.9%) showed high participation rate. A total of 1,012,206 individuals with valid results of interferon-gamma release assay (IGRA) were selected to constitute the IGRA cohort. Most of the enrolled participants in the IGRA cohort were in their working age. Approximately, three-quarters of total enrolled population were female. Investigating the LTBI prevalence, stages of LTBI care cascade, natural history of LTBI, efficacy of LTBI treatment and cost-effectiveness of LTBI screening are feasible within this IGRA cohort.