New thesis investigates the role of memory T cells in viral infections and their importance for long-term immunity
Olga Rivera Ballesteros from the Center for Infectious Medicine (CIM) at the Departmet of Medicine, Huddinge (MedH) is defending her thesis titled "Circulating and Resident Memory T cell functions in viral diseases", on 21 March, 2025. Main supervisor is Marcus Buggert (MedH).
What is the main focus of your thesis?
When a virus enters the body, the immune system responds in two phases: an immediate innate defense followed by an adaptive response that builds long-term protection. Memory T cells play a key role in this immunity, with circulating types patrolling the blood and tissue-resident types guarding specific organs against future infections. This thesis explores how these memory T cells work in different viral infections, with a focus on Epstein-Barr virus (EBV), Human Immunodeficiency virus (HIV) and SARS-CoV-2 virus.
Which are the most important results?
First, we discovered that a specific type of T cell (CXCR5+ CD8+) resides in the tonsils, where EBV persists in the body, suggesting a role in controlling latent infection. Second, our findings indicate that in people living with HIV, the T cell compartment does not fully recover after therapy, neither in the blood nor in the gut—where we also show HIV is more commonly hidden. Finally, we show that functional T cell responses develop following SARS-CoV-2 infection, and that COVID-19 vaccination enhances both the frequency and function of these cells, contributing to long-lasting immunity.
How can this new knowledge contribute to the improvement of people’s health?
By exploring how different immune cells fight viral infections, this research aims to improve our understanding of immunity and contribute to the development of future vaccines and treatments against viral infections.
What are your future ambitions?
I would like to apply the scientific, analytical, and soft skills I have developed during my Ph.D. to a different field of work. Among the various viral infections I have studied over the years, I am particularly interested in HIV infection. I am eager to continue my career in a role where I can contribute to improving global access to HIV treatments and make a meaningful impact on public health.
Dissertation
Friday, 21 March at 09:30, 9Q Månen, Alfred Nobels allé 8, Flemingsberg.
Thesis
Circulating and Resident Memory T cell functions in viral diseases.