Despite antiretroviral therapy, proviral latency of human immunodeficiency virus type 1 (HIV-1) remains a principal obstacle to curing the infection [1]. Inducing the expression of latent genomes within resting CD4+ T cells is the primary strategy to clear this reservoir [2]. While histone deacetylase (HDAC) inhibitors such as suberoylanilide hydroxamic acid (SAHA or vorinostat, VOR) can disrupt HIV-1 latency in vitro [3–5], the utility of this approach has never been directly proven in a translational clinical study of HIV-infected patients.Therefore we isolated the circulating resting CD4+ T cells of patients in whom viremia was fully suppressed by antiretroviral therapy (ART), and directly studied the effect of VOR in this latent reservoir. In each of eight patients studied, a single dose of VOR increased both biomarkers of cellular acetylation, and simultaneously induced an increase in HIV RNA expression in resting CD4+ cells (mean increase 4.8-fold). This is the first demonstration that a molecular mechanism known to enforce HIV latency can be therapeutically targeted in man, provides proof-of-concept for HDAC inhibitors as a new therapeutic class, and defines a precise approach to test novel strategies to directly attack and eradicate latent HIV infection.

Here we demonstrate that a combination of tenofovir, emtricitabine, and raltegravir effectively suppresses peripheral and systemic HIV replication in humanized BLT mice. We also demonstrate that antiretroviral therapy (ART)-treated humanized BLT mice harbor latently infected resting human CD4 ؉ T cells that can be induced ex vivo to produce HIV. We observed that the levels of infected resting human CD4 ؉ T cells present in BLT mice are within the range of those observed circulating in patients undergoing suppressive ART. These results demonstrate the potential of humanized BLT mice as an attractive model for testing the in vivo efficacy of novel HIV eradication strategies.

Development of specific IgE antibodies to the oligosaccharide galactose-α-1, 3-galactose (α-gal) following tick bites has been shown to be the source of red meat allergy. In this study, we investigated the presence of α-gal in four tick species: the lone-star tick ( Amblyomma americanum ), the Gulf-Coast tick ( Amblyomma maculatum ), the American dog tick ( Dermacentor variabilis ), and the black-legged tick ( Ixodes scapularis ) by using a combination of immunoproteomic approach and, carbohydrate analysis. Anti-α-gal antibodies identified α-gal in the salivary glands of both Am. americanum and Ix. scapularis , while Am. maculatum and De. variabilis appeared to lack the carbohydrate. PNGase F treatment confirmed the deglycosylation of N-linked α-gal-containing proteins in tick salivary glands. Immunolocalization of α-gal moieties to the salivary secretory vesicles of the salivary acini also confirmed the secretory nature of α-gal-containing antigens in ticks. Am. americanum ticks were fed on human blood (lacks α-gal) using a silicone membrane system to determine the source of the α-gal. N-linked glycan analysis revealed that Am. americanum and Ix. scapularis have α-gal in their saliva and salivary glands, but Am. maculatum contains no detectable quantity. Consistent with the glycan analysis, salivary samples from Am. americanum and Ix. scapularis stimulated activation of basophils primed with plasma from α-gal allergic subjects. Together, these data support the idea that bites from certain tick species may specifically create a risk for the development of α-gal-specific IgE and hypersensitivity reactions in humans. Alpha-Gal syndrome challenges the current food allergy paradigm and broadens opportunities for future research.

Eukaryotic cells have evolved a complex mechanism for sensing DNA damage during genome replication. Activation of this pathway prevents entry into mitosis to allow for either DNA repair or, in the event of irreparable damage, commitment to apoptosis. Under conditions of replication stress, the damage signal is initiated by the ataxia-telangiectasia-mutated and Rad3-related kinase ATR. We recently demonstrated that the human immunodeficiency virus type 1 (HIV-1) gene product viral protein R (Vpr) arrests infected cells in the G 2 phase via the activation of ATR. In the present study, we show that the activation of ATR by Vpr is analogous to activation by certain genotoxic agents, both mechanistically and in its downstream consequences. Specifically, we show a requirement for Rad17 and Hus1 to induce G 2 arrest as well as Vpr-induced phosphorylation of histone 2A variant X (H2AX) and formation of nuclear foci containing H2AX and breast cancer susceptibility protein 1. These results demonstrate that G 2 arrest mediated by the HIV-1 gene product Vpr utilizes the cellular signaling pathway whose physiological function is to recognize replication stress. These findings should contribute to a greater understanding of how HIV-1 manipulates the CD4 ؉ -lymphocyte cell cycle and apoptosis induction in the progressive CD4؉ -lymphocyte depletion characteristic of HIV-1 pathogenesis.

Antiretroviral therapy (ART) can reduce HIV levels in plasma to undetectable levels, but rather little is known about the effects of ART outside of the peripheral blood regarding persistent virus production in tissue reservoirs. Understanding the dynamics of ART-induced reductions in viral RNA (vRNA) levels throughout the body is important for the development of strategies to eradicate infectious HIV from patients. Essential to a successful eradication therapy is a component capable of killing persisting HIV infected cells during ART. Therefore, we determined the in vivo efficacy of a targeted cytotoxic therapy to kill infected cells that persist despite long-term ART. For this purpose, we first characterized the impact of ART on HIV RNA levels in multiple organs of bone marrow-liver-thymus (BLT) humanized mice and found that antiretroviral drug penetration and activity was sufficient to reduce, but not eliminate, HIV production in each tissue tested. For targeted cytotoxic killing of these persistent vRNA+ cells, we treated BLT mice undergoing ART with an HIV-specific immunotoxin. We found that compared to ART alone, this agent profoundly depleted productively infected cells systemically. These results offer proof-of-concept that targeted cytotoxic therapies can be effective components of HIV eradication strategies.