Early Lesion of Post-Primary Tuberculosis: Subclinical Driver of Disease and Target for Vaccines and Host-Directed Therapies

The characteristic lesion of primary tuberculosis is the granuloma as is widely studied in human tissues and animal models. Post-primary tuberculosis is different. It develops only in human lungs and begins as a prolonged subclinical obstructive lobular pneumonia that slowly accumulates mycobacterial antigens and host lipids in alveolar macrophages with nearby highly sensitized T cells. After several months, the lesions undergo necrosis to produce a mass of caseous pneumonia large enough to fragment and be coughed out to produce a cavity or be retained as the focus of a post-primary granuloma. Bacteria grow massively on the cavity wall where they can be coughed out to infect new people. Here we extend these findings with the demonstration of secreted mycobacterial antigens, but not acid fast bacilli (AFB) of M. tuberculosis in the cytoplasm of ciliated bronchiolar epithelium and alveolar pneumocytes in association with elements of the programmed death ligand 1 (PD-L1), cyclo-oxygenase (COX)-2, and fatty acid synthase (FAS) pathways in the early lesion. This suggests that M. tuberculosis uses its secreted antigens to coordinate prolonged subclinical development of the early lesions in preparation for a necrotizing reaction sufficient to produce a cavity, post-primary granulomas, and fibrocaseous disease.

Early Lesion of Post-Primary Tuberculosis: Subclinical Driver of Disease and Target for Vaccines and Host-directed Therapies.

The characteristic lesion of primary tuberculosis is the granuloma as is widely studied in human tissues and animal models. Post-primary tuberculosis is different. It develops only in human lungs and begins as a prolonged subclinical obstructive lobular pneumonia that slowly accumulates mycobacterial antigens and host lipids in alveolar macrophages with nearby highly sensitized T cells. After several months, the lesions undergo necrosis to produce a mass of caseous pneumonia large enough to fragment and be coughed out to produce a cavity or be retained as the focus of a post-primary granuloma. Here we extend these findings with the demonstration of mycobacterial antigen, but not AFB, of M. tuberculosis in the cytoplasm of ciliated bronchiolar epithelium and alveolar pneumocytes in association with elements of the programmed death ligand 1 (PD-L1), cyclo-oxygenase (COX)-2, and fatty acid synthase (FAS) pathways in the early lesion. This suggests that M. tuberculosis uses its secreted antigens to coordinate prolonged subclinical development of the early le-sions in preparation for a necrotizing reaction sufficient to produce a cavity, post-primary granulomas and fibrocaseous disease.

Early Lesion of Post-Primary Tuberculosis: Subclinical Driver of Disease and Target for Vaccines and Host-directed Therapies

The characteristic lesion of primary tuberculosis is the granuloma as is widely studied in human tissues and animal models. Post-primary tuberculosis is different. It develops only in human lungs and begins as a prolonged subclinical obstructive lobular pneumonia that slowly accumulates mycobacterial antigens and host lipids in alveolar macrophages with nearby highly sensitized T cells. After several months, the lesions under necrosis to produce a mass of caseous pneumonia large enough to fragment and be coughed out to produce a cavity or be retained as the focus of a post-primary granuloma. Here we extend these findings with the demonstration of mycobacterial antigen, but not AFB, of M. tuberculosis in the cytoplasm of ciliated bronchiolar epithelium and alveolar pneumocytes in association with elements of the programmed death ligand 1 (PD-L1), cyclo-oxygenase (COX)-2, and fatty acid synthase (FAS) pathways in the early lesion. This suggests that M. tuberculosis use its secreted antigens to coordinate prolonged subclinical development of the early lesions in preparation for a necrotizing reaction sufficient to produce a cavity, post-primary granulomas and fibrocaseous disease

Early Lesion of Post-Primary Tuberculosis: Subclinical Driver of Disease and Target for Vaccines and Hostdirected Therapies

Research on the pathogenesis of tuberculosis in recent years has focused largely on the granulomatous stage of primary tuberculosis. However, post-primary tuberculosis that accounts for 80% of clinical disease is seldom studied because of the paucity of animal models and human tissues. The early lesion of post-primary tuberculosis is a subclinical obstructive lobular pneumonia that develops asymptomatically for months accumulating secreted mycobacterial antigens in alveolar macrophages and highly sensitized T cells before onset of clinical disease. Here we demonstrate antigen of M. tuberculosis in the cytoplasm of ciliated bronchiolar epithelium and alveolar pneumocytes in association with elements of the programmed death ligand 1 (PD-L1), cyclo-oxygenase (COX)-2, and fatty acid synthase (FAS) pathways in the early lesion. This suggests a new synthesis of the pathogenesis of post-primary tuberculosis in which M. tuberculosis use its secreted antigens and cord factor to direct prolonged subclinical development of the early lesions in preparation for a sudden necrotizing reaction sufficient to produce a cavity and/or granulomas. Available evidence indicates that most successful human and animal vaccines and host directed therapies of post-primary tuberculosis target the early lesion, not granulomas. Recognition of this will facilitate design and evaluation of improved vaccines and therapies for tuberculosis.

A novel Trypanosoma cruzi secreted antigen as a potential biomarker of Chagas disease

Chagas drug discovery has been hampered by a lack of validated assays to establish treatment efficacy in pre-clinical animal models and in patients infected with T. cruzi. Reduced levels of parasite secreted antigens in the blood of infected hosts could be used to demonstrate treatment efficacy. A published proteomic study of parasite secreted antigens identified the hypothetical protein Tc_5171 as a secreted antigen. In this report, we developed Tc_5171 specific antibodies and showed that the native protein was expressed by the three life cycle stages of the parasite. Anti-peptide antibodies were able to detect the parasite antigen in blood of infected mice during the acute and the chronic phase of infection. Benznidazole treatment of infected mice significantly reduced their blood antigen levels. Of clinical significance, patients diagnosed with Chagas disease, either asymptomatic or with cardiac clinical symptoms had significantly higher Tc_5171 antigen levels compared to endemic controls. Pair-wise analysis, before and after Benznidazole treatment, of patients with asymptomatic Chagas disease showed a significant reduction in antigen levels post treatment. Taken together, our results indicate that Tc_5171 could be used as a novel biomarker of Chagas disease for diagnosis and to assess treatment efficacy.

Allergic activity and specificity of tuberculin preparations with 30-50% of weakly secreted mycobacterial antigens of tuberculosis

Bovine tuberculosis remains a global problem. An intracutaneous test with tuberculin is the main method for determining the status of herds, which poses special requirements for the activity and specificity. The basis of cotemporal tuberculins are antigens of tuberculosis mycobacteria easily secreted to the liquid synthetic medium during growth, but a range of antigens with a low secretion index are in composition of tuberculins in small quantities. The purpose of the research is to obtain weakly secreted antigens from a production waste – autoclaved bacterial mass of production strain of tuberculosis mycobacteria (MTB) using ultrasound and nonionic detergent, to study the diagnostic properties of tuberculosis with 30-50% of such antigens. It has been determined that autoclaved bacterial mass of industrial MBT strain, which is a waste of tuberculin production, can be an additional source of tuberculoproteins, which are low-secreting (LS) MBT antigens, which in an equivalent dose are about 30% more active compared to standard tuberculin based on easily secreted antigens and is not inferior in terms of species specificity. Whereas, up to 50% of purified LS of tuberculoproteins from the bacterial mass can be included in tuberculin composition. The obtained preparation is not reactogenic, in an equivalent dose it does not differ in terms of activity from the international standard for PPD of tuberculin, but surpasses it in terms of species specificity. It has been shown that in herds with an undetermined tuberculosis status, 2.2 times more cows respond to tuberculins with 30-50% of purified LS tuberculoproteins compared to standard preparations based on easily secreted antigens of tuberculosis mycobacterium. Profound studies of reacting cows using methods for detecting the genome of tuberculosis mycobacterium and bacteriological markers of tuberculosis infection have confirmed the presence of latent tuberculosis infection in cow body. The inclusion of up to 50% of tuberculoproteins from the bacterial mass in tuberculin increases the diagnostic properties of the target product and significantly reduces its price cost.

Evidence for vesicle-mediated antigen export by the human pathogen Babesia microti

The apicomplexan parasite Babesia microti is the primary agent of human babesiosis, a malaria-like illness and potentially fatal tick-borne disease. Unlike its close relatives, the agents of human malaria, B. microti develops within human and mouse red blood cells in the absence of a parasitophorous vacuole, and its secreted antigens lack trafficking motifs found in malarial secreted antigens. Here, we show that after invasion of erythrocytes, B. microti undergoes a major morphogenic change during which it produces an interlacement of vesicles (IOV); the IOV system extends from the plasma membrane of the parasite into the cytoplasm of the host erythrocyte. We developed antibodies against two immunodominant antigens of the parasite and used them in cell fractionation studies and fluorescence and immunoelectron microscopy analyses to monitor the mode of secretion of B. microti antigens. These analyses demonstrate that the IOV system serves as a major export mechanism for important antigens of B. microti and represents a novel mechanism for delivery of parasite effectors into the host by this apicomplexan parasite.