The role of CD8 T cells in anti-tuberculosis immunity in humans remains unknown, and studies of CD8 T cell–mediated protection against tuberculosis in mice have yielded controversial results. Unlike mice, humans and nonhuman primates share a number of important features of the immune system that relate directly to the specificity and functions of CD8 T cells, such as the expression of group 1 CD1 proteins that are capable of presenting Mycobacterium tuberculosis lipids antigens and the cytotoxic/bactericidal protein granulysin. Employing a more relevant nonhuman primate model of human tuberculosis, we examined the contribution of BCG- or M. tuberculosis-elicited CD8 T cells to vaccine-induced immunity against tuberculosis. CD8 depletion compromised BCG vaccine-induced immune control of M. tuberculosis replication in the vaccinated rhesus macaques. Depletion of CD8 T cells in BCG-vaccinated rhesus macaques led to a significant decrease in the vaccine-induced immunity against tuberculosis. Consistently, depletion of CD8 T cells in rhesus macaques that had been previously infected with M. tuberculosis and cured by antibiotic therapy also resulted in a loss of anti-tuberculosis immunity upon M. tuberculosis re-infection. The current study demonstrates a major role for CD8 T cells in anti-tuberculosis immunity, and supports the view that CD8 T cells should be included in strategies for development of new tuberculosis vaccines and immunotherapeutics.

SUMMARY:Anthrax is considered a serious biowarfare and bioterrorism threat because of its high lethality, especially by the inhalation route. Rhesus macaques (Macaca mulatta) are the most commonly used nonhuman primate model of human inhalation anthrax exposure. The nonavailability of rhesus macaques necessitated development of an alternate model for vaccine testing and immunologic studies. This report describes the median lethal dose (LD 50 ) and pathology of inhalation anthrax in cynomolgus macaques (Macaca fascicularis). Gross and microscopic tissue changes were reviewed in 14 cynomolgus monkeys that died or were killed after aerosol exposure of spores of Bacillus anthracis (Ames strain). The LD 50 and 95% confidence intervals were 61,800 (34,000 to 110,000) colony-forming units. The most common gross lesions were mild splenomegaly, lymph node enlargement, and hemorrhages in various organs, particularly involving the meninges and the lungs. Mediastinitis, manifested as hemorrhage or edema, affected 29% of the monkeys. Microscopically, lymphocytolysis occurred in the intrathoracic lymph nodes and spleens of all animals, and was particularly severe in the spleen and in germinal centers of lymph nodes. Hemorrhages were common in lungs, bronchial lymph nodes, meninges, gastrointestinal tract, and mediastinum. These results demonstrate that the Ames strain of B. anthracis is lethal by the inhalation route in the cynomolgus macaque. The LD 50 of the Ames strain of B. anthracis was within the expected experimental range of previously reported values in the rhesus monkey in an aerosol challenge. The gross and microscopic pathology of inhalation anthrax in the cynomolgus monkey is remarkably similar to that reported in rhesus monkeys and humans. The results of this study are important for the establishment of an alternative nonhuman primate model for evaluation of medical countermeasures against inhalational anthrax. (Lab Invest 2003, 83:1201-1209.A nthrax is caused by Bacillus anthracis, a Grampositive, aerobic or facultative anaerobic, rodshaped spore-forming bacterium. Infection follows dermal, gastrointestinal, or inhalation routes of entry, each with slightly different clinical manifestations; however, the final outcome, regardless of portal of entry, is often septicemia. The inhalation route is most lethal, with nonspecific initial clinical signs such as fever, malaise, headache, nausea, and vomiting. The spores are phagocytosed by pulmonary macrophages and germinate in the draining mediastinal and thoracic lymph nodes. Rapid progression to chest pain and respiratory distress leads to an almost 100% case fatality rate in humans. The incubation period in humans varies from 12 hours to 5 days, depending on the dose received, and can be longer following exposure to low doses or removal of therapeutics. Death is thought to be due to effects of the two major anthrax exotoxins, lethal toxin and edema toxin. Species differ in susceptibility, with ruminants most susceptible and carnivores generally less susceptible. Hig...

Little is known about the immune distribution and localization of antigen-specific T cells in mucosal interfaces of tissues/organs during infection of humans. In this study, we made use of a macaque model ofAccumulating evidence suggests that human ␥␦ T cells belong to nonclassical T cells that contribute to both innate and adaptive immune responses. Resident ␥␦ T cells within epithelia make up a portion of intraepithelial lymphocytes and may play a role in innate immunity against microbial invasions, immune surveillance of malignances, and even skin repair after damage (1, 16). Peripheral ␥␦ T cells circulating in the blood and lymphoid tissues appear to behave as both innate and adaptive immune cells (1, 5, 9, 16). Circulating V␥2V␦2 T cells exist only in primates and, in humans, constitute 60 to 95% of total blood ␥␦ T cells. Recent studies suggest that circulating V␥2V␦2 T cells in primates can recognize phosphoantigens from some bacteria, such as Mycobacterium tuberculosis, and possess both innate and adaptive immune features (1, 5, 9, 16). The finding that "unprimed" V␥2V␦2 T cells can recognize and react to wide ranges of nonpeptide ligands with the capability of "naïve" production of cytokines has been interpreted as a pattern recognition-like feature of innate immune cells.On the other hand, the capacity of V␥2V␦2 T cells to undergo major clonal expansion in primary infection and to mount rapid recall expansion upon reinfection has been proposed as an adaptive (memory-type) immune response of these ␥␦ T cells (5). Consistent with these memory-type responses is the demonstration of memory phenotypes of V␥2V␦2 T cells in the blood of humans (7).Tuberculosis (TB) is the second leading cause of death worldwide, killing about 1.8 million persons annually. While human CD4 T cells play a crucial role in immune protection against M. tuberculosis infection, other T-cell populations, including V␥2V␦2 T cells, are poorly characterized regarding their roles in immunity to TB. We recently demonstrated that Mycobacterium bovis BCG-vaccinated monkeys can mount memory-type immune responses of V␥2V␦2 T cells in the pulmonary compartment following M. tuberculosis infection by aerosol and that the rapid recall responses of these ␥␦ T cells coincide with protection against acutely fatal TB in juvenile rhesus monkeys (19). Nevertheless, immune responses of V␥2V␦2 T cells in patients with chronic TB appear to be suppressed (for a review, see reference 4). It has been debated whether the depression of the V␥2V␦2 T-cell response in TB is caused by the infection or allows the infection to progress (4). Further studies are needed to elucidate the biology and effector function of V␥2V␦2 T cells in M. tuberculosis infection.

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The major inducible 70-kDa heat shock protein (hsp72) increases measles virus (MV) transcription and genome replication. This stimulatory effect is attributed to hsp72 interaction with two highly conserved hydrophobic domains in the nucleocapsid protein (N) C terminus of Edmonston MV. These domains are known as Box-2 and Box-3. A single amino acid substitution in Box-3 of Edmonston MV (i.e., N522D) disrupts hsp72 binding. The prevalence of the N522D substitution in contemporary wild-type MV isolates suggests that this sequence has been positively selected. The present work determined if the N522D substitution enhances viral fitness and the degree to which any fitness advantage is influenced by hsp72 levels. Both parent Edmonston MV (Ed N) and an N522D substitution mutant (Ed N-522D) exhibited similar growth on Vero and murine neuroblastoma cells and in cotton rat lung, although Ed N-522D virus exhibited an attenuated in vitro response to hsp72 overexpression. In contrast, mixed infections showed a significantly reduced in vitro and in vivo fitness of Ed N-522D virus. Results support the involvement of additional selectional pressures that maintain the circulation of virus containing N-522D despite the cost to viral fitness.The measles virus (MV) RNA genome is packaged by the viral nucleocapsid protein (N) to form a helical nucleocapsid. The carboxyl-terminal 125 amino acids of the 525-amino-acid N protein (i.e., N TAIL ) is exposed on the surface of the nucleocapsid (8, 9). Sequence variability in the N protein C terminus reflects the fact that this protein domain is intrinsically disordered, imparting structural plasticity that allows it to mediate interactions with a variety of cellular and viral binding partners that include the viral P protein (1, 2, 10), the major inducible 70-kDa heat shock protein (hsp72) (29, 30), the cellular nucleoprotein receptor (12, 13), and interferon-responsive factor 3 (24). Binding events are localized to patches of hydrophobic amino acid side groups whose sequence is well conserved relative to the hypervariable sequence that is otherwise characteristic of N TAIL (4). These regions of exposed hydrophobicity are referred to as Box-1, Box-2, and Box-3.Stable complex formation between the viral P protein and N TAIL involves both high-affinity binding to Box-2 and lowaffinity binding to . By also binding the viral L protein, P tethers the viral L protein to the nucleocapsid template in support of transcription and genome replication, and it is this essential function that is the probable basis for constraints in Box-2 and Box-3 sequence variability. hsp72 also exhibits a high binding affinity for Box-2 and a low binding affinity for Box-3, a fact that would allow hsp72 to destabilize P/N TAIL complexes (29,30). It has been postulated that it is necessary to diminish the affinity between P and N TAIL in order to promote the repetitive cycle of binding and release that underlies polymerase processivity (2). Such a model could explain the increases in MV transcription and genome replic...