Annexin A2 in Virus Infection

Viral life cycles consist of three main phases: (1) attachment and entry, (2) genome replication and expression, and (3) assembly, maturation, and egress. Each of these steps is intrinsically reliant on host cell factors and processes including cellular receptors, genetic replication machinery, endocytosis and exocytosis, and protein expression. Annexin A2 (AnxA2) is a membrane-associated protein with a wide range of intracellular functions and a recurrent host factor in a variety of viral infections. Spatially, AnxA2 is found in the nucleus and cytoplasm, vesicle-bound, and on the inner and outer leaflet of the plasma membrane. Structurally, AnxA2 exists as a monomer or in complex with S100A10 to form the AnxA2/S100A10 heterotetramer (A2t). Both AnxA2 and A2t have been implicated in a vast array of cellular functions such as endocytosis, exocytosis, membrane domain organization, and translational regulation through RNA binding. Accordingly, many discoveries have been made involving AnxA2 in viral pathogenesis, however, the reported work addressing AnxA2 in virology is highly compartmentalized. Therefore, the purpose of this mini review is to provide information regarding the role of AnxA2 in the lifecycle of multiple epithelial cell-targeting viruses to highlight recurrent themes, identify discrepancies, and reveal potential avenues for future research

Engineering a hyperactive TcBuster transposase for efficient gene delivery for cell therapy applications

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Annexin A2 antibodies but not inhibitors of the annexin A2 heterotetramer impair productive HIV-1 infection of macrophages in vitro

During sexual transmission of human immunodeficiency virus (HIV), macrophages are initial targets for HIV infection. Secretory leukocyte protease inhibitor (SLPI) has been shown to protect against HIV infection of macrophages through interactions with annexin A2 (A2), which is found on the macrophage cell surface as a heterotetramer (A2t) consisting of A2 and S100A10. Therefore, we investigated potential protein-protein interactions between A2 and HIV-1 gp120 through a series of co-immunoprecipitation assays and a single molecule pulldown (SiMPull) technique. Additionally, inhibitors of A2t (A2ti) that target the interaction between A2 and S100A10 were tested for their ability to impair productive HIV-1 infection of macrophages. Our data suggest that interactions between HIV-1 gp120 and A2 exist, though this interaction may be indirect. Furthermore, an anti-A2 antibody impaired HIV-1 particle production in macrophages in vitro, whereas A2ti did not indicating that annexin A2 may promote HIV-1 infection of macrophages in its monomeric rather than tetrameric form

Nano-Pulse Stimulation induces immunogenic cell death in human papillomavirus-transformed tumors and initiates an adaptive immune response

<div><p>Nano-Pulse Stimulation (NPS) is a non-thermal pulsed electric field modality that has been shown to have cancer therapeutic effects. Here we applied NPS treatment to the human papillomavirus type 16 (HPV 16)-transformed C3.43 mouse tumor cell model and showed that it is effective at eliminating primary tumors through the induction of immunogenic cell death while subsequently increasing the number of tumor-infiltrating lymphocytes within the tumor microenvironment. <i>In vitro</i> NPS treatment of C3.43 cells resulted in a doubling of activated caspase 3/7 along with the translocation of phosphatidylserine (PS) to the outer leaflet of the plasma membrane, indicating programmed cell death activity. Tumor-bearing mice receiving standard NPS treatment showed an initial decrease in tumor volume followed by clearing of tumors in most mice, and a significant increase in overall survival. Intra-tumor analysis of mice that were unable to clear tumors showed an inverse correlation between the number of tumor infiltrating lymphocytes and the size of the tumor. Approximately half of the mice that cleared established tumors were protected against tumor re-challenge on the opposite flank. Selective depletion of CD8⁺ T cells eliminated this protection, suggesting that NPS treatment induces an adaptive immune response generating CD8⁺ T cells that recognize tumor antigen(s) associated with the C3.43 tumor model. This method may be utilized in the future to not only ablate primary tumors, but also to induce an anti-tumor response driven by effector CD8⁺ T cells capable of protecting individuals from disease recurrence.</p></div

T cell ignorance is bliss: T cells are not tolerized by Langerhans cells presenting human papillomavirus antigens in the absence of costimulation

Human papillomavirus type 16 (HPV16) infections are intra-epithelial, and thus, HPV16 is known to interact with Langerhans cells (LCs), the resident epithelial antigen-presenting cells (APCs). The current paradigm for APC-mediated induction of T cell anergy is through delivery of T cell receptor signals via peptides on MHC molecules (signal 1), but without costimulation (signal 2). We previously demonstrated that LCs exposed to HPV16 in vitro present HPV antigens to T cells without costimulation, but it remained uncertain if such T cells would remain ignorant, become anergic, or in the case of CD4+ T cells, differentiate into Tregs. Here we demonstrate that Tregs were not induced by LCs presenting only signal 1, and through a series of in vitro immunizations show that CD8+ T cells receiving signal 1+2 from LCs weeks after consistently receiving signal 1 are capable of robust effector functions. Importantly, this indicates that T cells are not tolerized but instead remain ignorant to HPV, and are activated given the proper signals. Keywords: T cell anergy, T cell ignorance, Immune tolerance, Human papillomavirus, HPV16, Langerhans cell

NPS treatment of tumors results in a CD8-dependent adaptive immune response.

<p>Shown are the individual tumor growth profiles of primary and rechallenge events in mice receiving NPS with or without selective depletion. Growth curves of primary (black) and re-challenge tumors (red) of NPS-treated mice with or without selective depletion of CD4 or CD8 T cells are displayed. <b>(A)</b> Mice received NPS treatment of primary tumor only (3 pps, 30 kV/cm, 70 A). <b>(B and C)</b> Mice received NPS treatment of primary tumor (3 pps, 30 kV/cm, 70A) followed by selective depletion of CD4 cells <b>(B)</b> or CD8 cells <b>(C)</b> with the administration of either an αCD4 mAb (yellow dots) or αCD8 mAb (green dots. The red arrows indicate the day of tumor re-challenge.</p

NPS application.

<p><b>(A)</b> Photo of a typical shaved C3.43 tumor prior to treatment. <b>(B)</b> Pinch electrode used to treat these tumors. <b>(C)</b> Pinch electrode sandwiching a tumor as NPS is applied. <b>(D)</b> Oscilloscope trace of voltage (top) and current (bottom) applied to the tumor in each pulse. <b>(E)</b> Photo of the treated tumor in “A” 11 days later.</p

NPS treatment of primary tumors results in significant levels of tumor clearance, enhanced survival, and is effective during multiple applications.

<p>Groups of 10 mice were s.c. challenged with C3.43 tumors. 10-days post tumor challenge mice were given NPS (3 pps, 30kV/cm) treatment at the tumor site. Mice with recurring tumors received a second treatment on day 31 <b>(A)</b> Mean tumor volume (±SEM) of untreated and NPS treated mice (*p<0.05, unpaired students t-test at each time point). Volume measurements of untreated group displayed until there was a loss of 3 or more mice within the group due to euthanasia endpoints met <b>(B)</b> 50-day survival curve of groups with no treatment (naïve, median survival 39 days) or NPS treatment (NPS) (p<0.0012, Mantel-Cox Log Rank test). Data are representative of 2 independent experiments.</p

Theta-Defensins Inhibit High-Risk Human Papillomavirus Infection Through Charge-Driven Capsid Clustering

Persistent infection with high-risk human papillomavirus (hrHPV) genotypes results in a large number of anogenital and head and neck cancers worldwide. Although prophylactic vaccination coverage has improved, there remains a need to develop methods that inhibit viral transmission toward preventing the spread of HPV-driven disease. Defensins are a class of innate immune effector peptides that function to protect hosts from infection by pathogens such as viruses and bacteria. Previous work utilizing α and β defensins from humans has demonstrated that the α-defensin HD5 is effective at inhibiting the most common high-risk genotype, HPV16. A third class of defensin that has yet to be explored are θ-defensins: small, 18-amino acid cyclic peptides found in old-world monkeys whose unique structure makes them both highly cationic and resistant to degradation. Here we show that the prototype θ-defensin, rhesus theta defensin 1, inhibits hrHPV infection through a mechanism involving capsid clustering that inhibits virions from binding to cell surface receptor complexes