Antiretroviral therapy has revolutionized HIV management, transforming a once rapidly fatal disease into a chronic condition. Yet, the necessity of lifelong adherence to ART poses significant challenges, including side effects, drug resistance, and socio-economic burdens. Therefore, the immunological holy grail remains: interventions that can induce long-term remission without continuous ART. Efforts have increasingly focused on harnessing the body’s own immune system, particularly the cytotoxic CD8⁺ T lymphocytes, which possess the intrinsic capacity to target and destroy infected cells.

Previous clinical observations have indicated that administering broadly neutralizing anti-HIV-1 antibodies in conjunction with strategic treatment interruptions can foster a durable decrease in viral loads for some patients. However, this promising outcome has been elusive and inconsistent, hampered by a limited understanding of the cellular and molecular attributes that underpin effective viral control post-treatment. The current study addresses this knowledge gap by providing an unprecedented longitudinal analysis of HIV-specific CD8⁺ T cell responses from four distinct ATI (analytical treatment interruption) trials involving bNAb recipients.

The researchers meticulously profiled immune cells extracted from participants, focusing on their proliferative capacity and phenotype prior to intervention. It was revealed that individuals who achieved PIC had superior HIV-specific CD8⁺ T cell responses even before receiving bNAb therapy. These T cells exhibited robust proliferation and bore markers indicative of stem cell-like memory, a phenotype associated with self-renewal and long-lived immunological memory. Such cells possess the unique ability to persist, adapt, and mount potent recall responses upon encountering viral antigens again, highlighting their critical role in sustained control.

Beyond identifying pre-intervention differences, the study uncovered that bNAb administration itself augmentated the stemness features of HIV-specific CD8⁺ T cells. This enhancement occurred without notable shifts in the diversity of T cell clonotypes or the emergence of novel clonotypes targeting HLA-optimal epitopes. This finding suggests that bNAbs might reinforce the function and quality of existing T cell populations rather than generating new specificities, thus magnifying the importance of pre-existing immune advantages.

Perhaps most strikingly, the integration of multimodal single-cell analyses—combining transcriptomic, proteomic, and epigenetic profiling—offered unprecedented insight into the molecular landscape governing effective HIV-specific CD8⁺ T cells. These cells were characterized by enhanced metabolic fitness, a critical determinant of cellular endurance and function in chronic infections. Concurrently, they exhibited signatures indicating decreased T cell exhaustion, a state often associated with immune dysfunction in persistent viral diseases. This molecular blueprint elucidates the sophisticated interplay between immunometabolism and functional capacity that enables these T cells to sustain control over HIV replication.

The implications of these insights are profound for the development of next-generation immunotherapeutic strategies. By defining the immune correlates of PIC, particularly the features of stem cell-like memory CD8⁺ T cells, the study paves the way for targeted interventions. Therapies designed to amplify these traits—whether through vaccine design, cellular engineering, or adjunctive antibody therapies—have the potential to transform HIV management, reducing or eliminating the need for lifelong ART.

Importantly, this work refutes the notion that simply boosting T cell numbers or diversifying their antigen specificity is enough to achieve durable viral suppression. Instead, the quality and functional capacity of T cells, rooted in their stem-like properties and metabolic robustness, emerge as the critical determinants of success. This paradigm shift focuses future research on enhancing T cell fitness rather than quantity alone.

Moreover, the longitudinal nature of the study, tracking immune dynamics before, during, and after bNAb intervention and ATI, offers valuable temporal context. Understanding how immune profiles evolve in response to treatment interruption and antibody administration sharpens the ability to predict which patients might achieve remission and to tailor interventions accordingly.

While the study’s findings are compelling, the authors acknowledge that the journey toward a functional HIV cure remains complex. The heterogeneity of patient responses, potential viral reservoir diversity, and the influence of host genetic factors mean that combination approaches will likely be necessary. Nevertheless, anchoring such strategies in the robust immunological principle of CD8⁺ T cell stemness represents a monumental step forward.

In conclusion, this pioneering investigation into the immunobiology of post-intervention control of HIV viremia sheds light on the indispensable role of stem cell-like memory CD8⁺ T cells. By delineating the molecular and functional hallmarks associated with durable viral remission, it sets the stage for novel therapeutic avenues aimed at achieving the long-sought goal of HIV remission without continuous therapy. As the field moves toward clinical translation, these insights provide hope for millions worldwide living with HIV, bringing the promise of remission within tangible reach.

Subject of Research:

HIV viral remission and CD8⁺ T cell immune responses in the context of broadly neutralizing antibody therapy and treatment interruption.

Article Title:

CD8⁺ T cell stemness precedes post-intervention control of HIV viremia

Article References:

Kiani, Z., Urbach, J.M., Wisner, H. et al. CD8⁺ T cell stemness precedes post-intervention control of HIV viremia. Nature (2025). https://doi.org/10.1038/s41586-025-09932-w

Image Credits:

AI Generated

HIV-1 remains a global health crisis, with approximately 40 million people living with the virus worldwide. Despite progress in managing the disease through antiretroviral therapy, challenges such as drug resistance, side effects, and social stigma persist, underscoring the urgent need for new therapeutic strategies. Integrase, long recognized for its function in inserting viral DNA into the infected host’s genome, has now been found to also engage viral RNA at later stages—highlighting previously uncharacterized roles in the HIV lifecycle.

The Salk research team employed cryo-electron microscopy (cryo-EM) to capture integrase in two distinct structural conformations. Initially, integrase operates as part of a massive “intasome” complex, consisting of four identical subunits arranged into a 16-part assembly. This architecture tightly encircles viral DNA, orchestrating its integration into the host genome, a critical step that establishes permanent infection within the host cell.

Later in the replication process, integrase adopts a drastically different form. It transitions from the large intasome to a minimalist four-part complex, a configuration associated with binding to viral RNA inside the HIV capsid. This structural transition from DNA-focused activity to RNA interaction reveals the protein’s adaptability and suggests additional layers of complexity in HIV’s replication machinery.

This discovery marks the first time researchers have visualized integrase’s RNA-bound state, providing a high-resolution blueprint for this elusive form. Such structural insights are invaluable, as the design of targeted inhibitors typically relies on detailed knowledge of a protein’s 3D configuration to effectively disrupt its function without off-target effects.

The implication of integrase functioning beyond DNA integration is profound. While current integrase inhibitors such as Dolutegravir effectively block the protein’s DNA integration role, HIV’s rapid mutation rate often leads to resistance. By targeting integrase’s secondary role in RNA interaction, drug developers may circumvent existing resistance mechanisms, opening the door to new classes of antiretroviral therapies.

Senior author Dmitry Lyumkis, PhD, emphasizes the significance of these findings: “We are only beginning to understand the multifunctionality of integrase proteins. Mapping its interaction with RNA not only enriches our knowledge of viral biology but also informs the rational design of next-generation HIV therapeutics.”

At the molecular level, HIV’s retroviral replication strategy involves reverse-transcribing its RNA genome into DNA, which is then inserted into the host’s genome via integrase. This insertion transforms the host cell into a viral factory, producing progeny RNA that is packaged for new infections. Understanding the full scope of integrase’s roles in this cycle is essential for developing comprehensive antiviral strategies.

The integrase’s structural plasticity uncovered by the Salk team illustrates the dynamic nature of viral proteins. Their data show how subtle shifts in quaternary structure—disassembling from a 16-subunit “lock” to a compact 4-subunit complex—enable integrase to pivot between its DNA and RNA binding functions. Such dynamic assembly-disassembly processes could be exploited pharmacologically to trap the protein in inactive states.

This research represents a collaboration among numerous experts across molecular biology, structural biology, and virology, including significant contributions from partnering institutions such as the University of Colorado School of Medicine, Dana-Farber Cancer Institute, and the National Institute of Diabetes and Digestive and Kidney Diseases. Their collective expertise underscores the complexity and interdisciplinary nature of combatting HIV.

The study also showcases the power of cryo-electron microscopy, which has revolutionized structural biology by enabling the visualization of large and flexible protein complexes in near-native states. The high-resolution cryo-EM maps generated by the researchers provide unparalleled detail into integrase’s architecture, setting a new standard for future investigations of viral proteins.

Beyond its scientific merit, this discovery carries translational potential for public health. Novel integrase inhibitors targeting both DNA and RNA-related functions may reduce drug resistance, improve treatment durability, and mitigate adverse effects. Such advances are critical in the ongoing global effort to curb HIV transmission and improve the quality of life for millions affected by the virus.

As the scientific community digests these findings, follow-up studies are anticipated to confirm integrase’s RNA interaction mechanisms, assess their roles in viral encapsidation and infectivity, and explore the potential for targeting these interactions therapeutically. This evolving picture of integrase’s biology promises to reshape HIV drug development paradigms in the coming years.

The Salk Institute’s pioneering research not only deepens our fundamental understanding of HIV biology but also exemplifies the fusion of structural insights and therapeutic innovation. With new blueprints in hand, drug designers are now better equipped than ever to develop integrase-targeting agents that could transform the clinical management of HIV-1 infection and ultimately help turn the tide against this enduring pandemic.

Subject of Research: Structural and functional analysis of HIV-1 integrase in its dual roles interacting with viral DNA and RNA.

Article Title: Structural Elucidation of HIV-1 Integrase Reveals Dual Functionality in Viral DNA Integration and RNA Interaction

News Publication Date: October 24, 2025

Web References:
https://www.nature.com/articles/s41467-025-64479-8

References:
Lyumkis, D., Jing, T., Shan, Z., et al. (2025). Structural insights into HIV-1 integrase functions during DNA integration and RNA interaction. Nature Communications. DOI: 10.1038/s41467-025-64479-8

Image Credits:
Salk Institute

When SARS-CoV-2, the coronavirus that causes COVID-19, began spreading worldwide in 2020, many research teams immediately set to work developing a vaccine against it. Building on decades of previous work on mRNA technology and on other viral vaccines, including HIV, they achieved their goal within the year. The most widely used mRNA vaccine design contains the genetic instructions for the body to make the spike protein that the virus uses to enter cells. The resulting immune response protects against infection and, more importantly, disease and death. However, developing a vaccine for HIV has proven much more difficult.

“The COVID-19 vaccines were an enormous achievement but the spike protein on SARS-CoV-2 was like low-hanging fruit for vaccinologists,” said Dr. John Moore, professor of microbiology and immunology at Weill Cornell Medicine and part of an international team that has brought biomedicine closer than ever to an HIV vaccine. “It behaves like its counterparts on viruses for which vaccines are relatively easy to develop, such as influenza. Unfortunately, we learned back in the 1990s how hard it is to make an HIV vaccine.”

Building a stable env protein

The goal of immunization with a viral protein, or some portion of it, is to limit infection by teaching the body to generate neutralizing antibodies that bind to these viral proteins and block their interaction with the receptors found on the cell’s surface. These antibodies can also flag virus-infected cells for destruction by other immune system components.

For SARS-CoV-2, this viral target is called the spike protein; its counterpart on HIV is the envelope (Env) protein trimer. But HIV researchers attempting to target Env in the 1990s discovered that when the three-subunit Env protein is produced in the laboratory it promptly falls apart. To create vaccine candidates for HIV, and later SARS-CoV-2 and respiratory syncytial virus (RSV), it was critical to engineer this kind of multi-subunit vaccine to be more stable.

In 1998, with funding from the National Institutes of Health, Dr. Moore launched an HIV vaccine project to tackle this problem. The challenge was engineering an Env protein trimer that was hardier but still resembled the original closely enough to elicit appropriate antibody responses in test animals, and then people. Dr. Moore was soon joined by Rogier Sanders, a graduate student who came from Amsterdam to work on the project as part of his dissertation. The first advance, published in 2000, involved engineering a new chemical bond that helped key trimer components to stick together without distorting their overall structure. The second key development, in 2002, was swapping one amino acid for another in one of the trimer subunits to fix another major source of instability.

Over the next decade, Dr. Sanders, working with Dr. Moore after he returned to Amsterdam, made several more modifications to the Env protein that enabled them to eventually build a truly stable trimer. They named it SOSIP.664, a term reflecting the nature of the successful modifications.

A collaboration with structural biologists Dr. Ian Wilson and Dr. Andrew Ward at Scripps Research in La Jolla provided critical insights by showing what the new trimer designs looked like when viewed by electron microscopy. The project also involved what Dr. Moore refers to as “sheer grunt work”. To find the best mimic of the Env protein as it appears on the surface of HIV, the team obtained genetic information for about 100 different HIV strains from around the world and then synthesized SOSIP.664 trimers from all of them. A battery of laboratory tests and, above all, structural analyses by the Scripps team enabled the researchers to find the genetic sequences that produced the best Env trimer.

This optimal sequence, designated BG505, was isolated from an infant born with HIV in Kenya by Dr. Julie Overbaugh of the Fred Hutch Cancer Center and her colleagues at the University of Nairobi. To help further HIV research, they had shared the information with the International AIDS Vaccine Initiative (IAVI), a co-funder of Dr. Moore’s team at that time.

A final breakthrough occurred when electron microscopy images showed how the assembled trimers were attracting fat molecules, causing them to aggregate into useless clumps. Once the researchers removed that part of the protein, they had the stable, engineered Env protein they wanted. They named it BG505 SOSIP.664.

Eliciting broadly neutralizing antibodies

Another major challenge in developing an HIV vaccine is that the virus mutates rapidly to evade detection by the immune system. Thus, people living with HIV around the world carry different versions of the Env protein. “It’s akin to what we saw with the COVID-19 variants, but much, much worse,” Dr. Moore said. An effective HIV vaccine must coax the immune system to make “broadly neutralizing antibodies” (bNAbs) capable of attacking many forms of the virus. “We know these antibodies exist, because some infected people make them, and we could show they bound to our SOSIP trimers,” added Dr. Moore. He and his colleague, Dr. P.J. Klasse, professor of research in microbiology and immunology at Weill Cornell Medicine, have been studying HIV neutralizing antibodies for over 25 years.

But could BG505 SOSIP.664 and other trimers the team soon made stimulate the production of bNAbs? Early tests in animal models showed that the BG505 trimers elicited antibodies specific for the infant’s strain, but not the bNAbs that neutralize a broad sample of viruses. The quest continued, now guided by ever-increasing knowledge of the underlying immunology.

Now, leading investigators are pursuing a multi-step immunization process known as “germline-targeting” to generate a lasting HIV vaccine response. This strategy involves activating the antibody-producing cells that make precursors of the broad neutralizers, then coaxing those antibodies along a path to full activity. A germline targeting SOSIP trimer, re-designed by the Sanders’ team and designated GT1.1, is in human trials supported by the Gates Foundation. A recent paper reported success in generating the desired bNAb precursors in a group of healthy volunteers. In an accompanying editorial, Weill Cornell professors Drs. Sallie Permar and Patrick Wilson outline why this approach to an HIV vaccine is so promising. Follow-up clinical trials in Africa are in progress or being planned also. The Moore/Sanders team is continuing its multi-year collaboration with the Permar group to further evaluate the GT1.1 trimer at the pre-clinical stage, as the accrued information can inform clinical trial design.

Progress in jeopardy

Projected decreases in NIH support for vaccine research and development, and other reductions in federal spending, could jeopardize these promising advances. Private philanthropy, including from the Gates Foundation, is vital, but can’t fully compensate for federal funding.

“The NIH has funded the basic design and development work for SOSIP trimer vaccines for over 20 years,” said Dr. Moore. “These were competitive grants. Everything is at risk.” But whatever the future holds, he notes how the COVID vaccines used the same principle of engineering stability into the spike protein. “So indirectly, our work on HIV helped make the COVID mRNA vaccines work as well as they did.”