Poster Presentation Second Round 16th Lorne Infection and Immunity 2026

Vδ2 T cell cytotoxic responses to malaria are innately mediated and enhanced in second infection (#134)

Nicholas Dooley 1 , Zuleima Pava 1 , Dean Andrew 2 , Teija Frame 2 , Jessica Loughland 1 , Kiana Berry 2 , Damian Oyong 1 , Fabian Rivera 2 , Reena Mukhiya 1 , Julianne Hamelink 1 , Luzia Bukali 2 , Jessica Engel 2 , Rebecca Webster 2 , James McCarthy 3 , Bridget Barber 2 , J. Alejandro Lopez 4 , Christian Engwerda 2 , Michelle Boyle 1
  1. Burnet Institute, Melbourne, VIC, Australia
  2. QIMR Berghofer / Griffith University, Herston, QLD, Australia
  3. The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
  4. Griffith University, Brisbane, Queensland, Australia

γδ T cells play critical roles in immunity to Plasmodium falciparum malaria, yet their functional heterogeneity and dynamics during primary and repeated infections remain poorly defined. Through longitudinal single-cell RNA sequencing of γδ T cells in malaria-naive volunteers undergoing controlled human malaria infection (CHMI), we uncovered 14 transcriptionally distinct clusters, revealing subset-specific activation trajectories and functional diversification. During primary infection, Vγ9Vδ2 T cells dominated peripheral responses, expanding into cytotoxic, inflammatory, antigen-presenting-like, and proliferating subsets, marked by upregulated cytotoxicity (GZMB, PRF1), MHC class II genes (HLA-DRA, CD74), and proliferation markers (MKI67, CDK1). Phenotypic validation via flow cytometry confirmed longitudinal activation, proliferation, and expansion of Vδ2 T cells, accompanied by increased cytotoxic protein expression (CD16, CD56, Granzyme B, Granulysin, Perforin, NKG7). Functional assays demonstrated innate cytotoxicity against blood-stage parasites in vitro, independent of Fc-dependent antibody activation. Despite induction of APC-like Vδ2 T cells by Pf during CHMI and in vitro, these cells failed to enhance naïve CD4+ T cell activation or drive parasite-specific antibody responses in CHMI. Secondary CHMI elicited terminal effector memory (TEMRA) Vδ2 T cells enriched for cytotoxic activation (Granzyme-B, Perforin, CD38), were correlated with monocyte-derived inflammatory mediators (CXCL9, S100A9) and systemic inflammation (elevated ART, CRP, CX3CL1) but not parasite clearance. JAK1/2 inhibition (ruxolitinib) during primary infection transiently suppressed cytotoxic activation but did not impair memory responses upon rechallenge. Notably, our findings provide a high-resolution atlas of γδ T cell responses in malaria, delineating their diverse roles while highlighting subset-specific adaptations during primary and memory immunity. These insights inform strategies to modulate γδ T cell function in malaria immunotherapy and vaccine design.