Ming Guo

TLR3 activation efficiency by high or low molecular mass poly I:C.

Toll-like receptor 3 (TLR3) plays a critical role in initiating type I IFN-mediated innate immunity against viral infections. TLR3 recognizes various forms of double stranded (ds) RNA, including viral dsRNA and a synthetic mimic of dsRNA, poly I:C, which has been used extensively as a TLR3 ligand to induce antiviral immunity. The activation efficiency of TLR3 by poly I:C is influenced by various factors, including size of the ligands, delivery methods and cell types. In this study, we examined the stimulatory effect of two commercially-available poly I:Cs [high molecular mass (HMM) and low molecular mass (LMM)] on TLR3 activation in various human cell types by determining the induction of type I and type III IFNs, as well as the antiviral effect. We demonstrated that the direct addition of both HMM- and LMM-poly I:C to the cultures of primary macrophages or a neuroplastoma cell line could activate TLR3. However, the transfection of poly I:C was necessary to induce TLR3 activation in other cell types studied. In all the cell lines tested, the efficiency of TLR3 activation by HMM-poly I:C was significantly higher than that by LMM-poly I:C. These observations indicate the importance and necessity of developing effective TLR3 ligands for antiviral therapy.

M. tuberculosis H37Rv Infection of Chinese Rhesus Macaques

Mycobacterium tuberculosis is the most common communicable infectious disease worldwide and the top killer of human immunodeficiency virus (HIV)-infected people. Because of common dual HIV and M. tuberculosis infections, the emergence of multidrug-resistant M. tuberculosis strains, the lack of effective vaccination, the morbidity, and the mortality of M. tuberculosis infection are increasing sharply. Therefore, there is an urgent need for vaccine and drug development against M. tuberculosis infection. These require appropriate animal models that closely resemble human disease. To this end, we infected Chinese rhesus macaques with the M. tuberculosis H37Rv strain. Bronchoscopy was used to inoculate nine monkeys with different doses of M. tuberculosis H37Rv strain. Regardless of the M. tuberculosis dose, all monkeys were infected successfully. This was shown by clinical, laboratory, and histopathology assessments. Among nine infected monkeys, six developed acute rapid progressive tuberculosis and the remaining animals mirrored early-stage chronic disease. These data, taken together, demonstrate that Chinese rhesus macaques are highly susceptible to M. tuberculosis infection and develop similar manifestations of disease that are seen in humans. This model affords new opportunities for studies of M. tuberculosis disease pathology and therapeutics.

Mycobacterium tuberculosis Erdman infection of rhesus macaques of Chinese origin

Continuous high global tuberculosis (TB) mortality rates and variable vaccine efficacy of mycobacterium Bacille Calmette-Guérin (BCG) emphasize the need for improved vaccines and drugs against TB, which require clinically relevant animal models for evaluation. We infected a total of 24 Chinese rhesus macaques with varying doses (CFU of 25, 100 and 500) of Mycobacterium tuberculosis (M.tb) Erdman strain via bronchoscopy. Regardless of the M.tb doses, all animals were infected successfully with minor differences in clinical progression; as evidenced by clinical manifestations, laboratory analyses, bacterial burden in infected tissues and histopathology evaluations. Rhesus macaques of Chinese origin are highly susceptible to infection with M.tb Erdman strain and develop acute TB disease, which is similar to that in humans. Pathologically, Chinese rhesus macaques recapitulated the complete spectrum of granulomatous lesions seen in human TB disease. These data indicate that low-dose infection of rhesus macaques of Chinese origin is a suitable model for acute M.tb infection.

Novel approaches to preclinical research and TB vaccine development.

The 4th Global Forum on TB Vaccines, convened in Shanghai, China, from 21 - 24 April 2015, brought together a wide and diverse community involved in tuberculosis vaccine research and development to discuss the current status of, and future directions for this critical effort. This paper summarizes the sessions on Low-Dose NHP Challenge Models, Novel Approaches to Animal Models for TB Vaccine R&D, Novel Antigen Delivery Strategies, and Next Generation TB Vaccines and Vaccine Concepts. Summaries of all sessions from the 4th Global Forum are compiled in a special supplement of Tuberculosis. [August 2016, Vol 99, Supp S1, S1-S30].

SIV Infection Facilitates Mycobacterium tuberculosis Infection of Rhesus Macaques

Tuberculosis (TB) is a common opportunistic infection and the leading cause of death for human immunodeficiency virus (HIV)-infected patients. Thus, it is necessary to understand the pathogenetic interactions between M.tb and HIV infection. In this study, we examined M.tb and/or simian immunodeficiency virus (SIV) infection of Chinese rhesus macaques. While there was little evidence that M.tb enhanced SIV infection of macaques, SIV could facilitate M.tb infection as demonstrated by X-rays, pathological and microbiological findings. Chest X-rays showed that co-infected animals had disseminated lesions in both left and right lungs, while M.tb mono-infected animals displayed the lesions only in right lungs. Necropsy of co-infected animals revealed a disseminated M.tb infection not only in the lungs but also in the extrapulmonary organs including spleen, pancreas, liver, kidney, and heart. The bacterial counts in the lungs, the bronchial lymph nodes, and the extrapulmonary organs of co-infected animals were significantly higher than those of M.tb mono-infected animals. The mechanistic studies demonstrated that two of three co-infected animals had lower levels of M.tb specific IFN-γ and IL-22 in PBMCs than M.tb mono-infected animals. These findings suggest that Chinese rhesus macaque is a suitable and alternative non-human primate model for SIV/M.tb coinfection studies. The impairment of the specific anti-TB immunity is likely to be a contributor of SIV-mediated enhancement M.tb infection.

Mycobacterium tuberculosis Erdman infection of cynomolgus macaques of Chinese origin

Background Nearly one-third of the population worldwide is estimated to have latent tuberculosis infection (LTBI), which represents a vast reservoir for a constant source of tuberculosis (TB) transmission. It has been suggested that cynomolgus macaques are less susceptible to Mycobacterium tuberculosis (M.tb) infection than rhesus macaques, we examined M.tb infection of Chinese cynomolgus macaques. Methods Eight Chinese cynomolgus macaques were infected with M.tb Erdman strain with a small [25 colony forming unit (CFU)] or large dose (500 CFU) via bronchoscopy. The infected animals were monitored for symptoms and examined by chest X-ray, computed tomography (CT), tuberculin skin test (TST), and enzyme-linked immunospot (ELISPOT). Results Based on TST conversion and the specific immune responses to M.tb antigens, all animals were successfully infected. Half of the animals developed active infection and died within 15 months postinfection. The other four animals were grouped with latent M.tb infection because of positive TST but few clinical signs and pathological changes of TB during the course of this study. Interestingly, a challenge with a large dose of M.tb also induced latent infection. Similar to the changes that occur with human TB patients, the animals with active infection exhibited weight loss, cough and typical TB pathological changes, including caseous granulomas, cavities, consolidation, lipid pneumonia, pleural effusion, lymphadenopathy and bacterial burden in lungs and other organs. Conclusions The low dose of M.tb was sufficient to cause both active and latent M.tb infection in cynomolgus macaques of Chinese origin.

Guinea pig infected with Mycobacterium tuberculosis via oral consumption

ABSTRACT Guinea pig represents a highly suitable animal model for study of Mycobacterium tuberculosis(Mtb)infection, as it demonstrates similarities to Mtb pulmonary infection in humans. It is known that guinea pigs can be efficiently infected by the respiratory or subcutaneous exposure to Mtb. However, information on Mtb infection through oral route is almost absent in the literature. Here, we examined whether guinea pigs can be infected by drinking Mtb containing water. Our findings confirmed that the guinea pigs could be infected with Mtb via drinking virulent water. The infected guinea pigs developed uniform oval-craterform ulcers at the 30th day after infection. Bacterial cultures showed Mtb growth in the lungs and spleens from the guinea pigs infected with high dose of Mtb. In addition, the infected animals had histopathological granulomatous lesions in lungs, spleens and mesenteric lymph nodes. We provide the compelling evidence that the guinea pigs could be infected by drinking Mtb containing water. The clinical and pathological observations in the infected animals were similar to those found in guinea pigs infected via the respiratory or subcutaneous routes.