Dr. Velarde’s research focuses on the pathogenesis of the Group A Streptococcus (GAS).  This pathogen most commonly causes non-invasive infections such as pharyngitis or skin infections.  However, it is also capable of causing aggressive invasive infections.  Dr. Velarde’s research focuses on the mechanisms by which GAS causes invasive disease.

GAS has been demonstrated to respond to LL-37, a human antimicrobial peptide, by up-regulating multiple virulence factors through a two-component system called the CsrRS (or CovRS) system.  Dr. Velarde’s work focuses on the mechanism by which LL-37 exerts this effect through the CsrS receptor, with the goal of understanding what role this interaction plays in the virulence of this pathogen.


Dr. Velarde received a BS in biology and BA in Spanish from the University of Maryland, College Park, in 1997.  He then joined the MD/PhD program at the University of Maryland, Baltimore and completed his graduate work in the laboratory of Dr. James Nataro, where he studied the pathogenesis of enteroaggregative Escherichia coli.  In 2006, he joined the pediatric residency program at the Cincinnati Children’s Hospital Medical Center (CCHMC).  Upon completion of his residency he spent a year working in the CCHMC emergency department and then transitioned, in 2010, to a fellowship in pediatric infectious diseases at the Boston Children’s Hospital.  His fellowship research was conducted in the laboratory of Dr. Michael Wessels.  In January of 2014 he joined the faculty in the division of infectious diseases at Boston Children’s Hospital.

Researcher Services

Researcher Areas

  • Group A Streptococcus Pathogenesis

Research Departments

Research Divisions


Publications powered by Harvard Catalyst Profiles

  1. Lynskey NN, Velarde JJ, Finn MB, Dove SL, Wessels MR. RocA Binds CsrS To Modulate CsrRS-Mediated Gene Regulation in Group A Streptococcus. MBio. 2019 Jul 16; 10(4). View abstract
  2. Carette X, Platig J, Young DC, Helmel M, Young AT, Wang Z, Potluri LP, Moody CS, Zeng J, Prisic S, Paulson JN, Muntel J, Madduri AVR, Velarde J, Mayfield JA, Locher C, Wang T, Quackenbush J, Rhee KY, Moody DB, Steen H, Husson RN. Multisystem Analysis of Mycobacterium tuberculosis Reveals Kinase-Dependent Remodeling of the Pathogen-Environment Interface. MBio. 2018 03 06; 9(2). View abstract
  3. Velarde JJ, O'Seaghdha M, Baddal B, Bastiat-Sempe B, Wessels MR. Binding of NAD+-Glycohydrolase to Streptolysin O Stabilizes Both Toxins and Promotes Virulence of Group A Streptococcus. MBio. 2017 09 12; 8(5). View abstract
  4. Sharma O, O'Seaghdha M, Velarde JJ, Wessels MR. NAD+-Glycohydrolase Promotes Intracellular Survival of Group A Streptococcus. PLoS Pathog. 2016 Mar; 12(3):e1005468. View abstract
  5. Velarde JJ, Ashbaugh M, Wessels MR. The human antimicrobial peptide LL-37 binds directly to CsrS, a sensor histidine kinase of group A Streptococcus, to activate expression of virulence factors. J Biol Chem. 2014 Dec 26; 289(52):36315-24. View abstract