Bacteria & Complement - Group Rooijakkers
Bacteria & Complement - Group Rooijakkers


We are interested in understanding the molecular interplay between bacteria and the complement system, an important part of the host immune response. Upon contact with bacteria, the plasma proteins of the complement system rapidly organize into a proteolytic cascade that generates chemoattractants to attract immune cells and labels bacteria for phagocytosis. Furthermore, complement directly kills bacteria via a pore-forming complex. We focus on deciphering the mechanistic insights on how bacteria are killed by complement. This will create new avenues for blocking the undesired complement activation during systemic infections and will improve desired complement activation by therapeutic antibodies and vaccination strategies in infectious diseases.

Research program

Infection and Immunity

Research interests

Innate immunity
Bacterial infections
Host-pathogen interaction


Yvonne Hagenaar


Related website

Group members


Priscilla Kerkman
Bart Bardoel
Leire Aguinagalde Salazar
Dani Heesterbeek

Research technician

Maartje Ruyken


PhD students

Dennis Doorduijn
Elena Boero
Eva Struijf
Julia Egido Egido
Lisanne de Vor
Rita Cruz
Sjors van der Lans


Yvonne Hagenaar

Join our group

Check for availability for bachelor and master level research internships with Kok van kesselor Bart Bardoel  

Key publications

  1. Heesterbeek DAC, Martin NI, Velthuizen A, Duijst M, Ruyken M, Wubbolts R, Rooijakkers SHM, Bardoel BW. “Complement-dependent outer membrane perturbation sensitizes Gram-negative bacteria to Gram-positive specific antibiotics.” Scientific Reports. 2019 Feb 28;9(1):3074. doi: 10.1038/s41598-019-38577-9. (Pubmed: 30816122) View
  2. Zwarthoff SA, Berends ETM, Mol S, Ruyken M, Aerts PC, Józsi M, de Haas CJC, Rooijakkers SHM, Gorham RD Jr. “Functional Characterization of Alternative and Classical Pathway C3/C5 Convertase Activity and Inhibition Using Purified Models.” Frontiers in Immunology. 2018 Jul 23;9:1691. doi: 10.3389/fimmu.2018.01691. (Pubmed: 30083158) View
  3. Garcia BL, Zwarthoff SA, Rooijakkers SH, Geisbrecht BV. “Novel Evasion Mechanisms of the Classical Complement Pathway.” Journal of Immunology 2016 Sep 15;197(6):2051-60: doi: 10.4049/jimmunol.1600863 (Pubmed: 27591336) View
  4. Stapels DA, Ramyar KX, Bischoff M, von Köckritz-Blickwede M, Milder FJ, Ruyken M, Eisenbeis J, McWhorter WJ, Herrmann M, van Kessel KP, Geisbrecht BV, Rooijakkers SH. “Staphylococcus aureus secretes a unique class of neutrophil serine protease inhibitors”.Proc Natl Acad Sci USA. 2014 Sep 9;111(36):13187-92. (Pubmed: 25161283) View
  5. Ko YP, Kuipers A, Freitag CM, Jongerius I, Medina E, van Rooijen WJ, Spaan AN, van Kessel KP, Höök M, Rooijakkers SH. Phagocytosis escape by a Staphylococcus aureus protein that connects complement and coagulation proteins at the bacterial surface. PLoS Pathogens. 2013 Dec;9(12):e1003816. (Pubmed: 24348255) View

PhD theses

How antibodies drive complement activation : Paving the road towards effective therapeutics

Seline Zwarthoff

How complement kills bacteria: A pore way to die

Dani Heesterbeek

Funding & Grants







Selected as EMBO Young investigator programme 


Young Investigator Award for Research in Complement