Expanding Immune Response Testing to Support Vaccine Development

In this Pharmaceutical Executive video interview, Nigel McCracken, chief operating officer, Virax Biolabs, discusses results from new data on the role of T cell dysfunction in post-acute infection syndromes (PAIS) at the World Immune Regulatory Conference in Switzerland. These syndromes are characterized by persistent, often debilitating symptoms that linger long after the initial infection has resolved. With growing recognition of the immune system’s role in driving these conditions, Virax's research focused on identifying biomarkers of immune exhaustion to better understand and potentially diagnose PAIS.

Pharmaceutical Executive: What role do you see Virax Biolabs playing in the broader field of immune diagnostics beyond PAIS?

Nigel McCracken: Referring back to the post-acute study, our goal is to provide clinicians with actionable information about a patient’s T cell dysfunction and how it correlates with their symptoms. Currently, it can take anywhere from one to two and a half years for patients to receive a diagnosis. We aim to significantly shorten that timeline to enable earlier treatment and better management.

What we’re really focused on is assessing adaptive immune status. Our ViraxImmune platform is central to this, and we’re looking to expand it into other indications.

For example, in the context of transplant patients, understanding immune status is critical. If someone has a compromised immune system, the immunosuppressants they receive post-transplant could lead to the reactivation of latent viruses, which can cause complications. That’s an area where we’re actively working to develop diagnostics—specifically around the detection and management of viral reactivation.

Another important area is protective immunity and memory T cell response. While antibody production following vaccination typically lasts about six months, what's more crucial is whether the vaccine elicits a durable immune response. Memory T cells are key to clearing pathogens upon re-exposure. We see a clear opportunity to support companies in evaluating vaccine efficacy through immune response testing—not just antibody levels.

Lastly, we’re also exploring diagnostics in the context of CAR T cell therapy for hematological cancers. These therapies are often administered after other treatments like chemotherapy or radiation. As CAR T therapies move toward more "off-the-shelf" or allogeneic options, it's critical to understand if a patient’s immune system—often compromised from previous treatments—can support the therapy. The number and function of T cells directly impact both efficacy and safety, and diagnostics can play a crucial role in patient selection and treatment optimization.

Full Interview Summary:At the recent World Immune Regulatory Conference in Switzerland, Virax Biolabs presented pivotal findings on T cell dysfunction in post-acute infection syndromes (PAIS), such as long COVID, myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), and chronic Lyme disease. The team explored how persistent immune activation post-infection leads to T cell exhaustion, a phenomenon well-documented in oncology but now increasingly relevant in chronic infectious conditions. Their study demonstrated that prolonged antigen stimulation in vitro caused upregulation of key exhaustion markers—PD-1, LAG-3, TIM-3, TIGIT, and CD39—on both CD4+ and CD8+ T cells. These markers were associated with impaired cytokine production, helping to distinguish individuals with PAIS from healthy controls.

Virax’s post-acute assay, under development, measures T cell cytokine responses after stimulation with peptides derived from various viruses, including SARS-CoV-2 and latent viruses like herpes. This dual-layered approach allows for detection of general immune dysfunction and identification of specific viral triggers. Importantly, it highlights how chronic antigen exposure can leave the immune system in a prolonged inflammatory state, unable to fully clear infections or return to baseline.

Beyond PAIS, Virax aims to extend its immune diagnostic platform into broader areas such as transplant medicine and oncology. In transplant patients, monitoring latent viral reactivation and immune competence could prevent complications like organ rejection. In oncology, particularly with CAR-T therapies, understanding immune status could inform dosing strategies and predict efficacy and safety. The company is pursuing collaborations with academic research centers in the UK and US, while engaging with the FDA on clinical study pathways. Virax Biolabs seeks to shorten diagnostic timelines, enable earlier interventions, and expand the scientific understanding of immune dysfunction across multiple disease states.