Research

Precisely controlling latent reservoirs

After infection, a portion of HIV-infected cells go into a resting, latent, state. In this state, HIV can hide from the immune system for years, forming the latent reservoir. The goal of HIV cure studies is to reduce or eliminate the latent reservoir so that people living with HIV can stop taking HIV drugs. However, it is challenging to measure the impact of curative therapies on HIV reservoirs. To address this issue, we are developing a model to set the number of latently infected cells in macaques precisely. Our goal for this model is to evaluate the predictive value of reservoir assays, test prospective HIV cure therapies, and determine how far latent reservoirs need to be reduced to achieve sustained HIV remission.

Alloimmunization as a novel HIV vaccine

The variability of HIV makes it difficult to develop an effective vaccine that directly targets the virus. To avoid viral diversity, we are exploring an alternative vaccine approach by focusing immune responses against host molecules that are incorporated into the virus as it buds from infected cells. Using a unique monkey model we are testing whether vaccine-induced antibodies against major histocompatibility complex (MHC) molecules can prevent AIDS virus transmission.

 

Isolating monoclonal antibodies

Antibodies are molecules produced by B cells that bind germs and other foreign substances to mark them for removal from the body. We are developing methods to isolate antibodies from individual B cells, called monoclonal antibodies, from animals used in infectious disease and organ transplant research. With this approach, we are isolating antibodies binding particular macaque MHC and killer-immunoglobulin-like receptor (KIR) molecules. These antibodies are useful for tracking specific populations of cells. This strategy may also be a helpful tool for characterizing antibody responses against pathogens.

Our paper describing our work: Isolating anti-Mamu-A1*001 antibody

Developing an HIV cure model in macaques

The “Berlin” and “London” patients were “cured” of HIV after receiving bone marrow transplants from donors with the CCR5-Δ32 mutation. In collaboration with Drs. Igor Slukvin and Ted Golos, we are developing a nonhuman primate model that replicates key features of the treatment regimens given the Berlin and London patients. In this project, we are exploring whether donor immune cells can attack and shrink latent reservoirs after bone marrow transplants.

Normal CD4+ cells (left) are susceptible to HIV infection because they express a functional CCR5 molecule on their surface and allowing HIV to infect the cells. A rare subset of individuals (right), from which the Berlin and London patients received bone marrow transplants, have a mutation in the CCR5 gene that prevents HIV from efficiently infecting cells.

Dog leukocyte antigen (DLA)-88 genotyping

Major histocompatibility complex class I (MHC-I) are cell surface molecules that help the immune system distinguish healthy and diseased cells. Within human and animal populations, many versions of the MHC-I genes exist as alleles. These differences ensure that at least some individuals make a sufficient immune response to fight off a pathogen. As a result, specific MHC-I variants associate with either good or bad disease outcomes. Therefore, it is important to know which MHC variant an individual expresses to understand the influence of MHC-I in cancer and infectious disease research. In comparative oncology studies, client-owned dogs that develop cancer are increasingly used to develop improved treatments for humans and dogs. We are adapting next-generation sequencing technologies to improve the characterization of MHC class I genes (DLA-88) in dogs to assist these studies.

Mapping minor histocompatibility antigens

Minor histocompatibility antigens (mHAgs) are T-cell epitopes derived from host proteins. Clinically, the mHAgs are important following organ transplants of MHC-matched individuals. For example, following bone marrow transplant donor T cells react against mHAgs on the surface of recipient cells. In this context, donor cells recognize “foreign” peptides presented by “self” MHC on the surface of recipient cells. If mHAgs are present exclusively on the surface of hematopoietic cells it can lead to the destruction of the recipient’s hematopoietic system, including malignant cells, in a beneficial process known as graft-versus-leukemia/lymphoma (GvL) reactivity. It is remarkably difficult to identify mHAgs due to the size of the genome and the number of potential differences between individuals. We are developing the methods to map mHAgs in Mauritan cynomolgus macaques using a combination of cellular immunology and genomics. We are attempting to uncouple the beneficial attributes of GvL from the detrimental effects of graft-versus-host disease (GvHD) by identifying hematopoietic cell-restricted mHAgs.

The conceptual outline for mapping mHAgs in Mauritian cynomolgus macaques. (1) exome sequence the genomes of MHC-identical MCM, (2) generate bulk mHAg-reactive T cell lines, (3) single-cell sort mHAg-reactive T-cell clones, (4) test clones against a panel of BLCL from exome sequenced MCM, (5) group into BLCL that induce clone reactivity or non-reactivity, and (6) segregation analysis to identify candidate mHAgs.