A Mouse Model for Latent Tuberculosis (original) (raw)
Related papers
A Mouse Model for Slowly Progressive Primary Tuberculosis
Scandinavian Journal of Immunology, 1999
Mustafa T, Phyu S, Nilsen R, Jonsson R, Bjune G. A Mouse Model for Slowly Progressive Primary Tuberculosis. Scand J Immunol 1999;50:127-136 The progression from primary Mycobacterium tuberculosis infection to disease is usually slow in humans. The aim of this study was to develop and characterize a mouse model for slowly progressive primary tuberculosis, using the intraperitoneal (i.p.) route of infection, and to compare it with our previously described model of latent M. tuberculosis infection. B6D2F1 hybrid mice inoculated with 1.5 × 10 6 colony-forming units (CFUs) of M. tuberculosis H37Rv were followed-up for 70 weeks. Lungs, livers and spleens were examined for bacillary growth, histopathological changes and mycobacterial antigens (MPT64, ManLAM and multiple antigens of M. tuberculosis), by immunohistochemical staining. The infection was found to pass through three distinctive phases. During phase 1, mice were healthy despite development of small granulomas and an increasing number of bacilli in the lungs. During phase 2, mice were unwell but mortality was low. The count of M. tuberculosis and the granuloma size stabilized. The granulomas contained an increasing population of large, vacuolated macrophages. During phase 3, mice became moribund and died rapidly, but the M. tuberculosis count remained relatively stable. The inflammatory infiltrates filled Ϸ 80% of the lung parenchyma and the lesions were not well demarcated. Rapidly progressing inflammation, rather than an increase in the M. tuberculosis count, seems to contribute more to mortality.
Guinea pig model of Mycobacterium tuberculosis latent/dormant infection
Microbes and Infection, 2008
Most experimental studies of latent or dormant tuberculosis infection have been conducted in murine models. Although guinea pigs are considered one of the animals that best reproduce human tuberculosis, surprisingly little data exist describing latent or dormant infection in these animals. The present work addresses this issue and shows that guinea pigs infected with a streptomycin auxotrophic mutant of Mycobacterium tuberculosis (strain 18b) replicate most of the known clinical, immunological, and pathological manifestations of this phase of the infectious process in humans. To establish infection, animals were inoculated with the mutant followed by administration of streptomycin for three weeks. Withdrawal of streptomycin caused microbial dormancy and few microorganisms remained viable and could be recovered from the animals' lungs and spleen several months later. Guinea pigs with dormant infection steadily gained weight and presented no clinical signs (scuff fur and lethargy) of active disease. The histopathology of the tuberculous lesions mimicked human lesions well. In addition, PBMC from infected animals strongly responded to stimulation with PPD or soluble culture filtrate proteins of M. tuberculosis throughout the duration of the experiment (six months). Finally, the tuberculin skin test (a clinical hallmark of latent infection) performed in guinea pigs infected with the auxotrophic mutant remarkably reproduced the response of humans to this test. Together, these findings confirm that infection of guinea pigs with M. tuberculosis strain 18b results in an infectious process that can be used as an interesting alternative model of latent or dormant tuberculosis infection in this animal specie.
Mouse Models for Mycobacterium tuberculosis Pathogenesis: Show and Do Not Tell
Pathogens
Science has been taking profit from animal models since the first translational experiments back in ancient Greece. From there, and across all history, several remarkable findings have been obtained using animal models. One of the most popular models, especially for research in infectious diseases, is the mouse. Regarding research in tuberculosis, the mouse has provided useful information about host and bacterial traits related to susceptibility to the infection. The effect of aging, sexual dimorphisms, the route of infection, genetic differences between mice lineages and unbalanced immunity scenarios upon Mycobacterium tuberculosis infection and tuberculosis development has helped, helps and will help biomedical researchers in the design of new tools for diagnosis, treatment and prevention of tuberculosis, despite various discrepancies and the lack of deep study in some areas of these traits.
Lessons from experimental Mycobacterium tuberculosis infections
Microbes and Infection, 2006
Mycobacterium tuberculosis is the cause of enormous human morbidity and mortality each year. Although this bacterium can infect and cause disease in many animals, humans are the natural host. For the purposes of studying the pathogenesis of M. tuberculosis, as well as the protective and immunopathologic host responses against this pathogen, suitable animal models must be used. However, modeling the human infection and disease in animals can be difficult, and interpreting the data from animal models must be done carefully. In this paper, the animal models of tuberculosis are discussed, as well as the limitations and advantages of various models. In particular, the lessons we have learned about tuberculosis from the mouse models are highlighted. The careful and thoughtful use of animal models is essential to furthering our understanding of M. tuberculosis, and this knowledge will enhance the discovery of improved treatment and prevention strategies.
Models of latent tuberculosis: Their salient features, limitations, and development
Journal of Laboratory Physicians, 2011
ABSTRACTLatent tuberculosis is a subclinical condition caused by Mycobacterium tuberculosis, which affects about one-third of the population across the world. To abridge the chemotherapy of tuberculosis, it is necessary to have active drugs against latent form of M. tuberculosis. Therefore, it is imperative to devise in vitro and models of latent tuberculosis to explore potential drugs. In vitro models such as hypoxia, nutrient starvation, and multiple stresses are based on adverse conditions encountered by bacilli in granuloma. Bacilli experience oxygen depletion condition in hypoxia model, whereas the nutrient starvation model is based on deprivation of total nutrients from a culture medium. In the multiple stress model dormancy is induced by more than one type of stress. In silico mathematical models have also been developed to predict the interactions of bacilli with the host immune system and to propose structures for potential anti tuberculosis compounds. Besides these in vitr...
Spontaneous Latency in a Rabbit Model of Pulmonary Tuberculosis
The American Journal of Pathology, 2012
Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), is an exquisitely adapted human pathogen capable of surviving for decades in the lungs of immune-competent individuals in the absence of disease. The World Health Organization estimates that 2 billion people have latent TB infection (LTBI), defined by a positive immunological response to Mtb antigens, with no clinical signs of disease. A better understanding of host and pathogen determinants of LTBI and subsequent reactivation would benefit TB control efforts. Animal models of LTBI have been hampered generally by an inability to achieve complete bacillary clearance. Herein, we have characterized a rabbit model of LTBI in which, similar to most humans, complete clearance of pulmonary Mtb infection and pathological characteristics occurs spontaneously. The evidence that Mtb-CDC1551-infected rabbits achieve LTBI, rather than sterilization, is based on the ability of the bacilli to be reactivated after immune suppression. These rabbits showed early activation of T cells and macrophages and an early peak in the TNF␣ level, which decreased in association with clearance of bacilli from the lungs. In the absence of sustained tumor necrosis factor-␣ production, no necrosis was seen in the evolving lung granulomas. In addition, bacillary control was associated with down-regulation of several metalloprotease genes and an absence of lung fibrosis. This model will be used to characterize molecular markers of protective immunity and reactivation. 1711-1724; http://dx.
Clinical & …, 2002
Mycobacterium tuberculosis produces latent infection or progressive disease. Indeed, latent infection is more common since it occurs in one-third of the world's population. We showed previously, using human material with latent tuberculosis, that mycobacterial DNA can be detected by in situ PCR in a variety of cell types in histologically-normal lung. We therefore sought to establish an experimental model in which this phenomenon could be studied in detail. We report here the establishment of such a model in C57Bl/6 × DBA/2 F1 hybrid mice by the intratracheal injection of low numbers of virulent mycobacteria (4000). Latent infection was characterized by low and stable bacillary counts without death of animals. Histological and immunological study showed granulomas and small patches of alveolitis, with high expression of tumour necrosis factor alpha (TNFα), inducible nitiric oxide synthase (iNOS), interleukin 2 (IL-2) and interferon gamma (IFNγ). In contrast, the intratracheal instillation of high numbers of bacteria (1 × 106) produced progressive disease. These animals started to die after 2 months of infection, with very high bacillary loads, massive pneumonia, falling expression of TNF-α and iNOS, and a mixed Th1/Th2 cytokine pattern. In situ PCR to detect mycobacterial DNA revealed that the most common positive cells in latently-infected mice were alveolar and interstitial macrophages located in tuberculous lesions, but, as in latently-infected human lung, positive signals were also seen in bronchial epithelium, endothelial cells and fibroblasts from histologically-normal areas. Our results suggest that latent tuberculosis is induced and maintained by a type 1 cytokine pattern plus TNFα, and that mycobacteria persist intracellularly in lung tissue with and without histological evidence of a local immune response.
Location of Persisting Mycobacteria in a Guinea Pig Model of Tuberculosis Revealed by R207910
Antimicrobial Agents and Chemotherapy, 2007
The lengthy chemotherapy of tuberculosis reflects the ability of a small subpopulation of Mycobacterium tuberculosis bacteria to persist in infected individuals. To date, the exact location of these persisting bacteria is not known. Lung lesions in guinea pigs infected with M. tuberculosis have striking similarities, such as necrosis, mineralization, and hypoxia, to natural infections in humans. Guinea pigs develop necrotic primary lesions after aerosol infection that differ in their morphology compared to secondary lesions resulting from hematogenous dissemination. In infected guinea pigs conventional therapy for tuberculosis during 6 weeks reduced the bacterial load by 1.7 logs in the lungs and, although this completely reversed lung inflammation associated with secondary lesions, the primary granulomas remained largely unaffected. Treatment of animals with the experimental drug R207910 (TMC207) for 6 weeks was highly effective with almost complete eradication of the bacteria throughout both the primary and the secondary lesions. Most importantly, the few remnants of acid-fast bacilli remaining after R207910 treatment were to be found extracellular, in a microenvironment of residual primary lesion necrosis with incomplete dystrophic calcification. This zone of the primary granuloma is hypoxic and is morphologically similar to what has been described for human lung lesions. These results show that this acellular rim may, therefore, be a primary location of persisting bacilli withstanding drug treatment.
Tuberculosis, 2008
Mouse tuberculosis (TB) models that utilize genetically susceptible mouse strains demonstrate many features of human lung disease. In the present study, pathology caused by progressive M. tuberculosis H37Rv infection in TB-susceptible I/St mice following the low-dose aerosol challenge showed close similarity to human TB, with formation of necrotic granuloma with adjusting B-cell-rich follicles. A remarkable feature was the development of hypoxic zones around TB lesions by day 60 of infection. Necrotizing inflammatory foci were abundantly infiltrated with Ly-6Gþ neutrophils. The levels of mRNA for neutrophil-recruiting factors (KC, MIP-2, IL-17 and IL-6) were all significantly increased in infected compared to naïve animals. A profound elevation of the mRNA level for IFN-g resulted neither in mycobacterial growth inhibition, nor in IL-17 response counter-regulation. Three-month therapy with RIF and INH resulted in eradication of culturable mycobacteria (at least 9 months following withdrawal), recovery of the lung tissue structure, and normalization of inflammatory genes expression. However, stable mycobacterial DNA (M. tuberculosis-specific insertion IS6110 detected by the qrt-PCR) was retained in the lungs for a long time after culturable bacilli were eliminated, and combination of lung homogenate liquid cultures with auramine staining demonstrated the presence of acid-fast bacilli with unaltered mycobacterial morphology. The lack of mycobacterial growth on agar, their microscopic detection in concentrated liquid cultures, and the increase in numbers of IS6110 copies in vivo at late stages of cured infection suggest that in our model dormant M. tuberculosis survived in the host. ª