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Kenneth Whitaker Witwer, Ph.D.

Photo of Dr. Kenneth Whitaker Witwer, Ph.D.

Assistant Professor of Molecular and Comparative Pathobiology

Research Interests: microRNA; RNA interference; extracellular vesicles; exosomes; retrovirology; genome editing; HIV/AIDS; immunology; parasitology

Contact for Research Inquiries

Edward D. Miller Research Building
733 N. Broadway
Room 829
Baltimore, MD 21205 map
Phone: 410-955-9770
Fax: 410-955-9823

Email me


Dr. Kenneth W. Witwer is an assistant professor of molecular and comparative pathobiology at the Johns Hopkins University School of Medicine. His research focuses on extracellular RNA, biomarker discovery, and therapeutic modulation of innate and intrinsic defenses.

He received his undergraduate degree from Penn State University, where he studied biochemistry and molecular biology, German, and international politics. He earned a doctorate from the Biochemistry, Cellular and Molecular Biology Program at Johns Hopkins and received a National Science Foundation Graduate Research Fellowship. Dr. Witwer remained at Johns Hopkins to complete a postdoctoral fellowship in microRNA biomarker research, and he joined the faculty in 2011. more


  • Assistant Professor of Molecular and Comparative Pathobiology
  • Assistant Professor of Neurology



  • B.A., Pennsylvania State University (Pennsylvania) (1999)
  • Ph.D., Johns Hopkins University School of Medicine (Maryland) (2010)

Additional Training

Johns Hopkins University School of Medicine, Baltimore, MD, 2011, Molecular and Comparative Pathobiology

Research & Publications

Research Summary

Dr. Witwer investigates extracellular vesicles and RNA in human disease, including HIV infection and inflammatory disease. Ribonucleic acid (RNA) molecules are found not only inside, but also outside of human cells in biological fluids such as blood plasma, urine, and cerebrospinal fluid. Although normally very labile, these molecules are protected from degradation by molecular shuttles including extracellular vesicles (EV). Rapidly expanding research programs over the last several years indicate that EV and their nucleic acid cargo may provide early warning of disease, contribute to the defense against disease, and serve as models for effective therapies. Dr. Witwer is also actively assessing the effects of diet on extracellular RNA as a potential therapeutic approach.


NIH-funded projects

  • "Extracellular Vesicle-Mediated Immunomodulation in HIV Infection and Nicotine Abuse"
  • "Development of miRNA-based therapies to silence or purge the latent macrophage reservoir in HAND"
  • "Biomarkers of the HIV-associated neurocognitive disorders: plasma and CSF miRNAs in prediction, diagnosis and pathogenesis of HAND" (in collaboration with Dr. Janice Clements)
  • "Circulating cellular and extracellular noncoding RNAs in HIV-1 Elite Suppression" (in collaboration with Dr. Joel Blankson).

Research Opportunities

Rotation projects are available to Cellular and Molecular Medicine students. Local undergraduates with laboratory experience and a strong interest in HIV, RNA, or extracellular vesicle research are encouraged to inquire about available projects. Undergraduates in the Witwer lab have co-authored numerous publications and have earned:

  • Four young investigator awards from professional meetings;
  • One Dean's Undergraduate Research Award (DURA);
  • Three Provost's Undergraduate Research Awards (PURA);
  • Three Center for AIDS Research Baltimore HIV Scholars; and
  • A Second Decade Society scholarship.

Lab Website: Ken Witwer Laboratory

Technology Expertise Keywords

miRNA, genome editing, ultracentrifugation, microarray, RNA-seq, in situ hybridization, molecular biology, immunofluorescence, immunohistochemistry

Selected Publications

View all on Pubmed

Lotvall J, Hill AF, Hochberg F, Buzás EI, Di Vizio D, Gardiner C, et al. Minimal experimental requirements for definition of extracellular vesicles and their functions. Journal of Extracellular Vesicles 2014.

Witwer KW. Circulating MicroRNA Biomarker Studies: Pitfalls and Potential Solutions. Clinical Chemistry 2014.

Kim DK, Lee J, Kim SR, Choi DS, Yoon YJ, Kim JH, et al. EVpedia: a community web portal for extracellular vesicles research. Bioinformatics 2014.

Buchanan EL, McAlexander MA, Witwer KW. SAMHD1 expression in blood cells of HIV-1 elite suppressors and viraemic progressors. Journal of Antimicrobial Chemotherapy 2014.

Meulendyke KA, Ubaida-Mohien C, Drewes JL, Liao Z, Gama L, Witwer KW, et al. Elevated Brain Monoamine Oxidase Activity in SIV- and HIV-associated Neurological Disease. Journal of Infectious Diseases 2014.

Yu IW, Espinoza DA, McAlexander MA, Witwer KW. OpenArray profiling reveals no differential modulation of miRNA by positive and negative CD4+ T-cell immunoselection. Experimental Hematology 2013.

Witwer KW, McAlexander MA, Queen SE, Adams RJ. Real-time quantitative PCR and droplet digital PCR for plant miRNAs in mammalian blood provide little evidence for general uptake of dietary miRNAs: Limited evidence for general uptake of dietary plant xenomiRs. RNA Biology 2013.

Witwer KW, Buzas EI, Bemis LT, Bora A, Lasser C, Lotvall J, et al. Standardization of sample collection, isolation and analysis methods in extracellular vesicle research. Journal of Extracellular Vesicles 2013.

McAlexander MA, Phillips MJ, Witwer KW. Comparison of Methods for miRNA Extraction from Plasma and Quantitative Recovery of RNA from Cerebrospinal Fluid. Frontiers in Genetics 2013.

Academic Affiliations & Courses

Graduate Program Affiliation

Dr. Witwer is a faculty member of the Cellular and Molecular Medicine graduate program ( 

Activities & Honors


  • Young Investigator Award, 18th Conference on Retroviruses and Opportunistic Infections, 2011
  • Richard T. Johnson Young Investigator Award, International Society for NeuroVirology, 2009
  • Travel Grant, International Society for NeuroVirology, 2009
  • Keystone Symposia Scholarship, Keystone Symposia, 2011
  • Scholl Scholarship, Penn State University, 2001 - 2002
  • Turock Young Scientist Award, Turock Family Foundation, 2002
  • Center for AIDS Research Scholar Award, Johns Hopkins University , 2014
  • Graduate Research Fellowship, National Science Foundation , 2003 - 2006


  • International Society for Extracellular Vesicles, 2012
  • International Society for NeuroVirology, 2009
  • American Association for the Advancement of Science, 2002
  • American Society for Exosomes and Microvesicles, 2012
  • New York Academy of Sciences, 2009
  • Society for Laboratory Automation and Screening, 2012

Professional Activities

  • Associate Editor, Journal of Extracellular Vesicles
  • Editorial Board Member, Clinical Chemistry (American Association for Clinical Chemistry)
  • Panelist, Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) Scientific Advisory Panel (SAP) on RNAi technology as a pesticide, US Environmental Protection Agency
    Minutes of this 2014 Scientific Advisory Panel meeting can be found at .
  • Chair, Local Organizing Committee, ISEV2015, International Society for Extracellular Vesicles
    Coordinated the organization of an international meeting with >800 attendees in Bethesda, Maryland in April, 2015.
  • Executive Committee Member-at-Large, International Society for Extracellular Vesicles
  • Ad-hoc reviewer, More than 50 scientific journals

Videos & Media

Recent News Articles and Media Coverage

MicroRNA and Cancer Therapy. Science Friday, May, 2015. 

The Retraction War. Jill Neimark, Aeon. December, 2014.

Fact or Artifact? Jef Akst, The Scientist. October, 2014.

HIV Denial: Alive and Well in 2014. Tara Smith, Aetiology. September, 2014.

A Lethal Dose of RNA. Kai Kupferschmidt, Science, August, 2013.

So Science...May have Gotten it Wrong. Now What? Virginia Hughes, National Geographic Phenomena. July, 2013.

U.S. Government Accuses Open Access Publisher of Trademark Infringement. Jocelyn Kaiser, ScienceInsider. May, 2013.

Kenneth Witwer on microRNA and cellular BubblesFundamentals


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