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Utilizing the Antigen Capsid-Incorporation Strategy for the Development of Adenovirus Serotype 5-Vectored Vaccine Approaches

Adenovirus serotype 5 (Ad5) has been extensively modified with traditional transgene methods for the vaccine development. The reduced efficacies of these ...

University of Alabama at Birmingham

The parasitic protozoan Leishmania invades mammalian macrophages to establish infection. We reported previously that Leishmania manipulates the expression of several non-coding RNA genes (e.g. Alu RNA, B1 RNA, and signal recognition particle RNA) in macrophages to favor the establishment of their infection in the phagolysosomes of these cells (Ueda, Y., and Chaudhuri, G. (2000) J. Biol. Chem. 275, 19428-19432; Misra, S., Tripathi, M. K., and Chaudhuri, G. (2005) J. Biol. Chem. 280, 29364-29373). We report here the mechanism of this down-regulation. We found that the non-coding RNA (ncRNA) genes that are repressed by Leishmania infection in macrophages contain a "B-box" in their promoters and thus require the polymerase III transcription factor TFIIIC for their expression. We also found that Leishmania promastigotes through their surface protease (leishmanolysin or gp63) activate the thrombin receptor PAR1 in the macrophages. This activation of PAR1 raised the cytosolic concentration of Ca(2+) into the micromolar range, thereby activating the Ca(2+)-dependent protease μ-calpain. μ-Calpain then degraded TFIIIC110 to inhibit the expression of the selected ncRNA genes. Avirulent stocks of Leishmania not expressing surface gp63 failed to down-regulate ncRNAs in the exposed macrophages. Inhibition of PAR1 or calpain 1 in macrophages made them resistant to Leishmania infection. These data suggest that macrophage PAR1 and calpain 1 are potential drug targets against leishmaniasis.

Mechanism of down-regulation of RNA polymerase III-transcribed non-coding RNA genes in macrophages by Leishmania.

Leishmania is a group of parasitic protozoa that infect blood and tissue phagocytes including macrophages. We hypothesize that Leishmania is capable of establishing infection inside the macrophages because (a) they infect a subpopulation of macrophages; and (b) they "renovate" the macrophages before the establishment of infection. We found that only alternatively activated polarized M2 macrophages support Leishmania growth. Exposure of M2 macrophages to Leishmania promastigotes represses several selected RNA polymerase III (PolIII)-transcribed non-coding RNA (ncRNA) genes including those of 7SL RNA, vault RNA, and B2 RNA which have B-box element at their promoters. The B-box-binding transcription factor TFIIIC110 is down-regulated in Leishmania-exposed macrophages. Both the surface protease gp63 and the surface glycolipid LPG are required for the down-regulation of the ncRNAs in the M2 macrophages. We conclude that Leishmania surface gp63 collaborates with LPG to down-regulate TFIIIC110 in M2 macrophages to repress B-box containing ncRNA gene promoters.

Leishmania-induced repression of selected non-coding RNA genes containing B-box element at their promoters in alternatively polarized M2 macrophages.

Trypanosoma cruzi is the causative agent of Chagas disease. Chagas disease is an endemic infection that affects over 8 million people throughout Latin America and now has become a global challenge. The current pharmacological treatment of patients is unsuccessful in most cases, highly toxic, and no vaccines are available. The results of inadequate treatment could lead to heart failure resulting in death. Therefore, a vaccine that elicits neutralizing antibodies mediated by cell-mediated immune responses and protection against Chagas disease is necessary.

Anitra L. Farrow

Department of Medicine

University of Alabama at Birmingham

Utilizing the Antigen Capsid-Incorporation Strategy for the Development of Adenovirus Serotype 5-Vectored Vaccine Approaches

Anitra L. Farrow

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Department of Medicine

University of Alabama at Birmingham

Utilizing the Antigen Capsid-Incorporation Strategy for the Development of Adenovirus Serotype 5-Vectored Vaccine Approaches

Department of Medicine