I'm a molecular infection biologist by training, but shifted my focus from pathogens to hosts for my graduate research. During my PhD with Phil Spence in Edinburgh I studied both falciparum and vivax malaria using controlled human (re)infection models, collaborating closely with the groups of Simon Draper and Angela Minassian in Oxford. As a hybrid bioinformatician and experimentalist, I love systems immunology for answering complex questions about human health. For my postdoc, I study in how the human immune response to malaria evolves in infants as they become reinfected and age. I'm also interested in how such early-life immunological events, malaria and beyond, may affect vaccine responses and immune development later in life. I address this question by making use of a longitudinal study cohort of infants receiving monthly chemoprevention in Eastern Uganda, together with our collaborators at UC San Francisco and IDRC Uganda.

Honors & Awards

  • The Walter V. and Idun Berry Postdoctoral Fellowship Program, The Walter V. and Idun Berry Foundation (09/01/2023)

Stanford Advisors

All Publications

  • A systematic analysis of the human immune response to Plasmodium vivax. The Journal of clinical investigation Bach, F. A., Muñoz Sandoval, D., Mazurczyk, M., Themistocleous, Y., Rawlinson, T. A., Harding, A. C., Kemp, A., Silk, S. E., Barrett, J. R., Edwards, N. J., Ivens, A., Rayner, J. C., Minassian, A. M., Napolitani, G., Draper, S. J., Spence, P. J. 2023; 133 (20)


    BACKGROUNDThe biology of Plasmodium vivax is markedly different from that of P. falciparum; how this shapes the immune response to infection remains unclear. To address this shortfall, we inoculated human volunteers with a clonal field isolate of P. vivax and tracked their response through infection and convalescence.METHODSParticipants were injected intravenously with blood-stage parasites and infection dynamics were tracked in real time by quantitative PCR. Whole blood samples were used for high dimensional protein analysis, RNA sequencing, and cytometry by time of flight, and temporal changes in the host response to P. vivax were quantified by linear regression. Comparative analyses with P. falciparum were then undertaken using analogous data sets derived from prior controlled human malaria infection studies.RESULTSP. vivax rapidly induced a type I inflammatory response that coincided with hallmark features of clinical malaria. This acute-phase response shared remarkable overlap with that induced by P. falciparum but was significantly elevated (at RNA and protein levels), leading to an increased incidence of pyrexia. In contrast, T cell activation and terminal differentiation were significantly increased in volunteers infected with P. falciparum. Heterogeneous CD4+ T cells were found to dominate this adaptive response and phenotypic analysis revealed unexpected features normally associated with cytotoxicity and autoinflammatory disease.CONCLUSIONP. vivax triggers increased systemic interferon signaling (cf P. falciparum), which likely explains its reduced pyrogenic threshold. In contrast, P. falciparum drives T cell activation far in excess of P. vivax, which may partially explain why falciparum malaria more frequently causes severe disease.TRIAL NCT03797989.FUNDINGThe European Union's Horizon 2020 Research and Innovation programme, the Wellcome Trust, and the Royal Society.

    View details for DOI 10.1172/JCI152463

    View details for PubMedID 37616070

    View details for PubMedCentralID PMC10575735

  • Adaptive T cells regulate disease tolerance in human malaria medRxiv Bach, F. A., Munoz Sandoval, D., Nahrendorf, W., Ivens, A., Mazurczyk, M., Themistocleous, Y., Silk, S. E., Barrett, J. R., Edwards, N. J., Napolitani, G., Minassian, A. M., Draper, S. J., Spence, P. J. 2021
  • Repeat controlled human malaria infection of healthy UK adults with blood-stage Plasmodium falciparum: Safety and parasite growth dynamics. Frontiers in immunology Salkeld, J., Themistocleous, Y., Barrett, J. R., Mitton, C. H., Rawlinson, T. A., Payne, R. O., Hou, M. M., Khozoee, B., Edwards, N. J., Nielsen, C. M., Sandoval, D. M., Bach, F. A., Nahrendorf, W., Ramon, R. L., Baker, M., Ramos-Lopez, F., Folegatti, P. M., Quinkert, D., Ellis, K. J., Poulton, I. D., Lawrie, A. M., Cho, J. S., Nugent, F. L., Spence, P. J., Silk, S. E., Draper, S. J., Minassian, A. M. 2022; 13: 984323


    In endemic settings it is known that natural malaria immunity is gradually acquired following repeated exposures. Here we sought to assess whether similar acquisition of blood-stage malaria immunity would occur following repeated parasite exposure by controlled human malaria infection (CHMI). We report the findings of repeat homologous blood-stage Plasmodium falciparum (3D7 clone) CHMI studies VAC063C ( NCT03906474) and VAC063 ( NCT02927145). In total, 24 healthy, unvaccinated, malaria-naïve UK adult participants underwent primary CHMI followed by drug treatment. Ten of these then underwent secondary CHMI in the same manner, and then six of these underwent a final tertiary CHMI. As with primary CHMI, malaria symptoms were common following secondary and tertiary infection, however, most resolved within a few days of treatment and there were no long term sequelae or serious adverse events related to CHMI. Despite detectable induction and boosting of anti-merozoite serum IgG antibody responses following each round of CHMI, there was no clear evidence of anti-parasite immunity (manifest as reduced parasite growth in vivo) conferred by repeated challenge with the homologous parasite in the majority of volunteers. However, three volunteers showed some variation in parasite growth dynamics in vivo following repeat CHMI that were either modest or short-lived. We also observed no major differences in clinical symptoms or laboratory markers of infection across the primary, secondary and tertiary challenges. However, there was a trend to more severe pyrexia after primary CHMI and the absence of a detectable transaminitis post-treatment following secondary and tertiary infection. We hypothesize that this could represent the initial induction of clinical immunity. Repeat homologous blood-stage CHMI is thus safe and provides a model with the potential to further the understanding of naturally acquired immunity to blood-stage infection in a highly controlled, identifier NCT03906474, NCT02927145.

    View details for DOI 10.3389/fimmu.2022.984323

    View details for PubMedID 36072606

    View details for PubMedCentralID PMC9444061

  • Controlled human malaria infection with a clone of Plasmodium vivax with high-quality genome assembly. JCI insight Minassian, A. M., Themistocleous, Y., Silk, S. E., Barrett, J. R., Kemp, A., Quinkert, D., Nielsen, C. M., Edwards, N. J., Rawlinson, T. A., Ramos Lopez, F., Roobsoong, W., Ellis, K. J., Cho, J. S., Aunin, E., Otto, T. D., Reid, A. J., Bach, F. A., Labbé, G. M., Poulton, I. D., Marini, A., Zaric, M., Mulatier, M., Lopez Ramon, R., Baker, M., Mitton, C. H., Sousa, J. C., Rachaphaew, N., Kumpitak, C., Maneechai, N., Suansomjit, C., Piteekan, T., Hou, M. M., Khozoee, B., McHugh, K., Roberts, D. J., Lawrie, A. M., Blagborough, A. M., Nugent, F. L., Taylor, I. J., Johnson, K. J., Spence, P. J., Sattabongkot, J., Biswas, S., Rayner, J. C., Draper, S. J. 2021; 6 (23)


    Controlled human malaria infection (CHMI) provides a highly informative means to investigate host-pathogen interactions and enable in vivo proof-of-concept efficacy testing of new drugs and vaccines. However, unlike Plasmodium falciparum, well-characterized P. vivax parasites that are safe and suitable for use in modern CHMI models are limited. Here, 2 healthy malaria-naive United Kingdom adults with universal donor blood group were safely infected with a clone of P. vivax from Thailand by mosquito-bite CHMI. Parasitemia developed in both volunteers, and prior to treatment, each volunteer donated blood to produce a cryopreserved stabilate of infected RBCs. Following stringent safety screening, the parasite stabilate from one of these donors (PvW1) was thawed and used to inoculate 6 healthy malaria-naive United Kingdom adults by blood-stage CHMI, at 3 different dilutions. Parasitemia developed in all volunteers, who were then successfully drug treated. PvW1 parasite DNA was isolated and sequenced to produce a high-quality genome assembly by using a hybrid assembly method. We analyzed leading vaccine candidate antigens and multigene families, including the vivax interspersed repeat (VIR) genes, of which we identified 1145 in the PvW1 genome. Our genomic analysis will guide future assessment of candidate vaccines and drugs, as well as experimental medicine studies.

    View details for DOI 10.1172/jci.insight.152465

    View details for PubMedID 34609964

    View details for PubMedCentralID PMC8675201

  • Senescence in immunity against helminth parasites predicts adult mortality in a wild mammal. Science (New York, N.Y.) Froy, H., Sparks, A. M., Watt, K., Sinclair, R., Bach, F., Pilkington, J. G., Pemberton, J. M., McNeilly, T. N., Nussey, D. H. 2019; 365 (6459): 1296-1298


    Our understanding of the deterioration in immune function in old age-immunosenescence-derives principally from studies of modern human populations and laboratory animals. The generality and significance of this process for systems experiencing complex, natural infections and environmental challenges are unknown. Here, we show that late-life declines in an important immune marker of resistance to helminth parasites in wild Soay sheep predict overwinter mortality. We found senescence in circulating antibody levels against a highly prevalent nematode worm, which was associated with reduced adult survival probability, independent of changes in body weight. These findings establish a role for immunosenescence in the ecology and evolution of natural populations.

    View details for DOI 10.1126/science.aaw5822

    View details for PubMedID 31604239