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Vaccine Research Center (VRC)

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Julie E. Ledgerwood, D.O.

Julie E. Ledgerwood, D.O. 

Chief, Clinical Trials Program

Major Areas of Research

  • Clinical evaluation of candidate vaccines and monoclonal antibodies targeting HIV, influenza, malaria, filoviruses, alphaviruses, and other emerging infectious diseases
  • Translational immunology and vaccine research
  • Advanced clinical development including strategic planning, facilitation, support, and oversight of external clinical trials

Program Description

The VRC conducts basic, translational, and clinical research. The primary mission of the VRC Clinical Trials Program (CTP) is to carry out the clinical research component of this triad both through intramural conduct of clinical trials at the NIH Clinical Center and through a broad range of support for external trials conducted by VRC collaborators and partners. These trials include evaluation of candidate vaccines and monoclonal antibodies targeting HIV, influenza, and other emerging infections. A secondary mission of the CTP is to conduct translational immunology research.

Since 2001, the CTP has launched 42 research protocols involving candidate vaccines and monoclonal antibodies targeting HIV, smallpox, influenza, West Nile virus, Ebola, Marburg, severe acute respiratory syndrome (SARS), malaria, and chikungunya, enrolling over 6,000 volunteers. The CTP engages in efforts aimed at efficient vaccine clinical research practice (PDF).

The CTP has also advanced vaccine candidates into both domestic and international Phase Ib, II, and IIb trials. Advanced product development and larger clinical trials require partnership with external clinical trial networks operated or supported by other federal agencies, academia, non-profit organizations, or the private sector. The CTP plays an important role in the planning, conduct, oversight, and interpretation of external network clinical trials.

For updates on VRC scientific progress, visit


Julie E. Ledgerwood, D.O., is a vaccine clinical researcher and serves as chief of the Clinical Trials Program. She is also a principal investigator for Phase I and II vaccine clinical trials at the VRC, studying the safety and immunogenicity of vaccines and monoclonal antibodies targeting HIV, influenza, Ebola, malaria, and other emerging infectious diseases. After completing a residency in internal medicine at Johns Hopkins Bayview Medical Center in Baltimore in 2002, Dr. Ledgerwood joined NIAID as a clinical fellow in allergy and immunology. In 2003, she joined the VRC as a clinical investigator. Dr. Ledgerwood is board-certified in allergy and immunology by the American Board of Allergy and Immunology and board- certified in internal medicine by the American Board of Internal Medicine. She is a graduate of Phillips University and the Oklahoma State University Center for Health Sciences, College of Osteopathic Medicine.

Research Group

Nina Berkowitz, M.P.H.

Senior Program Manager, Clinical Trial Recruitment and Community Outreach

Nina Berkowitz joined the VRC Clinical Trials Core in 2008 as a community outreach and recruitment specialist. In this role, she served as a primary point-of-contact for potential volunteers. Ms. Berkowitz designs, implements, monitors, and evaluates volunteer recruitment strategies and outreach efforts that increase awareness of the VRC clinical research program. Ms. Berkowitz’s prior experience involves community health education, in-clinic support group management, and research concerning global healthcare infrastructure and health disparities. Ms. Berkowitz completed her M.P.H. in epidemiology at George Washington University in 2013 and her B.S. in biology at Virginia Tech in 2007, with minors in both Spanish and medicine and society.

Pamela Costner, R.N., B.S.N., C.D.E.

Research Nurse/Study Coordinator

Pam Costner joined the VRC Clinical Trials Core team as a research nurse/study coordinator in 2006. She had served as a nurse in various capacities since 1987. Ms. Costner was an HIV counselor/educator in the late 1980s in Florida and for most of her career has operated in the public health system. She served the HIV-positive population in a large public hospital in Seattle. Ms. Costner joined NIH in 2001 with the kidney transplant nursing unit. Ms. Costner earned her certification in diabetes education and served as a protocol coordinator for two years with the National Institute of Diabetes and Digestive and Kidney Disease.

Mary E. Enama, M.A., P.A.-C.

Protocol Operations Manager

Mary E. Enama is the protocol operations manager for the VRC. She joined the VRC Clinical Trials Core in January 2002. Her responsibilities include protocol development and related project management to ensure the scientific quality, regulatory compliance, and timely implementation of clinical trials; protocol-specific data collection plans; and reporting clinical trials outcomes. Ms. Enama was educated first as a field biologist/laboratory scientist at Franklin and Marshall College (B.A.) and Washington University in St. Louis (M.A.) and later as a physician assistant at Medical College of Georgia (B.S).

Ingelise Gordon, R.N.

Clinical Operations Manager

Ingelise Gordon has been at NIH since 1991. She joined the VRC in July 2002 as a research nurse/study coordinator and now manages the clinical team of research nurses and administrative staff for VRC clinical trials targeting HIV and other emerging infectious diseases. Ms. Gordon has served throughout NIAID in the inpatient, outpatient, and day hospital nursing units. She has also worked as a case manager for HIV protocols in two different NIAID HIV clinics. Ms. Gordon worked in a dual role as both the clinic coordinator for NIAID's outpatient 11 clinic while also serving as a case manager for NIAID's HIV primary care clinic.

Cynthia Starr Hendel, C.R.N.P., CCRC

Nurse Practitioner

Cynthia Starr Hendel serves as a nurse practitioner and an associate investigator for the VRC Clinical Trials Core. Ms. Hendel joined the VRC after working in Phase I/II clinical trials with HIV preventive vaccines for more than five years at the Institute of Human Virology, University of Maryland, Baltimore, where she served as nurse practitioner and clinic coordinator for the onsite HIV Vaccine Trials Network unit. Her career in nursing has always emphasized health promotion and disease prevention.

LaSonji Holman, R.N., M.S.N., F.N.P.

Nurse Practitioner

LaSonji Holman is a nurse practitioner with the VRC Clinical Trials Core. Ms. Holman developed a passion for preventive medicine early in her career. Most recently, she worked as the senior nurse practitioner for Children's Hospital's Employee Health Clinic in Washington, DC, where she diligently provided health education, risk reduction, and primary health screening for the hospital's employees and volunteers. Formerly, Ms. Holman worked for Johns Hopkins University Center for Immunization Research as a practitioner for Phase I, II, and III HIV vaccine clinical trials.

Brenda D. Larkin, R.N., B.S.N., CCRC

Strategic Advisor for Special Projects

Ms. Larkin joined the VRC in 2002 as a senior clinical research associate. In 2005, she became clinical operations manager, leading staff and activities related to vaccine clinical trials, including guiding local and national outreach to ensure adequate and proper volunteer enrollment. Currently, Ms. Larkin serves as strategic advisor for special projects, managing external contracts related to key VRC research, and serves as a liaison to other government organizations and the community. Ms. Larkin previously served as research nurse coordinator with the Johns Hopkins University, Center for Immunization Research (CIR), where she conducted Phase I, II, and III preventive HIV vaccine trials. Ms. Larkin also served as both medical coordinator and nurse coordinator at the Greater Lawrence Health Center in Massachusetts and was responsible for the medical care of HIV-positive patients and HIV training and education of medical providers through the Massachusetts Care and Advocacy Program (MassCap). Ms. Larkin is a certified clinical research coordinator through the Association of Clinical Research Professionals.

Floreliz Mendoza, R.N.

Research Nurse/Study Coordinator

Floreliz Mendoza, R.N., joined the VRC in May 2009 as a research nurse. She began working at NIH as a clinical research nurse in 2001 in the Solid Organ/Tissue Transplant Unit until 2004. She then served as a float pool nurse at NIH where she managed patients with diverse illnesses. Ms. Mendoza coordinates various VRC clinical trials.

Laura Novik, R.N., B.S.N., M.A.

HIV Vaccine Studies Coordinator

Laura Novik joined the VRC as a research nurse/study coordinator in 2003. Ms. Novik began working as a research nurse at NIH in 2000 at the National Cancer Institute/National Naval Medical Center, where she coordinated Phase II prostate cancer vaccine trials. Prior to that, she spent 18 years in nephrology nursing working in varying roles as a primary care nurse, quality management coordinator, and administrator. Beginning in the early 1980's, Ms. Novik was also involved with HIV and AIDS in the clinical setting.

Sarah H. Plummer, R.N., M.S.N., N.P.

Senior Nurse Practitioner

Sarah H. Plummer serves as a senior nurse practitioner with the Clinical Trials Core. Ms. Plummer previously managed Phase II, III, and IV HIV clinical research trials for the Community Research Initiative of New England, a small, non-profit research organization. While there, she successfully facilitated the testing a new class of investigational, injectable HIV medications known as fusion inhibitors. Ms. Plummer has worked extensively in nursing research, having been responsible for all levels of conducting complex HIV clinical trials.

Jamie Saunders, R.N., B.S.N.

Research Nurse/Study Coordinator

Jamie Saunders joined the VRC in 2009 as a research nurse. She started working with HIV/AIDS patients as a nursing student at Louisiana State University Health Sciences Center in New Orleans. Before joining the VRC, Ms. Saunders worked at a clinic providing women's health services, which included counseling and education about HIV.

Sandra Sitar, M.S.

Director of Communications and Public Affairs

Sandra Sitar, M.S., serves as the director of communications and public affairs for the VRC Clinical Trials Core. In this role, Ms. Sitar serves as the primary liaison with external constituencies to represent and communicate the mission of the Clinical Trials Core. Ms. Sitar develops content for external and internal communications including online and print materials, as well as public education and promotional materials. She joined the VRC as a community outreach and recruitment specialist in 2005. Ms. Sitar's prior experience involves developing marketing strategies, producing public health education campaigns, grant and proposal writing, and course development on both high school and university levels. Ms. Sitar holds an M.S. from the London School of Economics and a B.A. from the University of California, Berkeley.

Brandon G. Wilson, M.H.S.M., B.S.W.

Senior Program Manager

Brandon G. Wilson joined the Clinical Trials Core in 2009 as a community outreach and recruitment specialist. In this role, he served as a primary point-of-contact for potential volunteers. Mr. Wilson plans and manages recruitment and community outreach initiatives. He has previously served in various management and leadership positions for community-based organizations, national organizations, and bio-pharmaceutical marketing firms leading projects in blockbuster therapies for hepatitis C virus, fetal cell research, and cervical cancer. He has also served on various non-profit boards, Ryan White HIV/AIDS Planning Councils, and HIV/AIDS Community Planning Groups. Mr. Wilson received his B.A. in social work from Oral Roberts University in 2002 and his masters of health systems management, concentrating in patient safety and risk management from George Mason University in 2013. Mr. Wilson is a member of Upsilon Phi Delta, a national healthcare administration honor society.

Galina Yamshchikov, M.S.

Protocol Specialist

Galina Yamshchikov, M.S., joined the VRC as a protocol specialist in 2009. Ms. Yamshchikov earned two master of science degrees: one in biochemistry from the Moscow State University in Russia and one in clinical investigation from the University of Virginia in Charlottesville. She gained valuable regulatory experience during her research fellowship at the FDA. Ms. Yamshchikov has significant scientific expertise in clinical research, immunology, and immune monitoring for clinical studies in the therapeutic areas of infectious diseases, allergy, and oncology. During her time at Emory University and at the University of Virginia, she was involved in scientific projects that included assay development and validation for clinical studies. As a clinical trials manager with Organization United Biosource Corporation, she managed clinical trials for the pharmaceutical industry, with projects ranging from the early development Phase I studies to post-marketing Phase IV studies.

Kathryn Zephir, R.N., B.S.N., B.A., M.S.

Research Nurse/Study Coordinator

Kathryn Zephir joined the VRC in 2008 as a research nurse. Prior to nursing, Ms. Zephir worked in the accounting/finance industry. Being a CFO for a non-profit hospice led to a career change to nursing. Ms. Zephir became interested in clinical research during her education at the Johns Hopkins School of Nursing.

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Selected Publications

Ledgerwood JE, DeZure AD, Stanley DA, Novik L, Enama ME, Berkowitz NM, Hu Z, Joshi G, Ploquin A, Sitar S, Gordon IJ, Plummer SA, Holman LA, Hendel CS, Yamshchikov G, Roman F, Nicosia A, Colloca S, Cortese R, Bailer RT, Schwartz RM, Roederer M, Mascola JR, Koup RA, Sullivan NJ, Graham BS; the VRC 207 Study Team. Chimpanzee Adenovirus Vector Ebola Vaccine - Preliminary Report. N Engl J Med. 2014 Nov 26.

Kibuuka H, Berkowitz NM, Millard M, Enama ME, Tindikahwa A, Sekiziyivu AB, Costner P, Sitar S, Glover D, Hu Z, Joshi G, Stanley D, Kunchai M, Eller LA, Bailer RT, Koup RA, Nabel GJ, Mascola JR, Sullivan NJ, Graham BS, Roederer M, Michael NL, Robb ML, Ledgerwood JE; the RV 247 Study Team. Safety and immunogenicity of Ebola virus and Marburg virus glycoprotein DNA vaccines assessed separately and concomitantly in healthy Ugandan adults: a phase 1b, randomised, double-blind, placebo-controlled clinical trial. Lancet. 2014 Dec 22.

Sarwar UN, Costner P, Enama ME, Berkowitz N, Hu Z, Hendel CS, Sitar S, Plummer S, Mulangu S, Bailer RT, Koup RA, Mascola JR, Nabel GJ, Sullivan NJ, Graham BS, Ledgerwood JE; VRC 206 Study Team. Safety and immunogenicity of DNA vaccines encoding ebolavirus and marburgvirus wild-type glycoproteins in a phase I clinical trial. J Infect Dis. 2015 Feb 15;211(4):549-57.

Chang LJ, Dowd KA, Mendoza FH, Saunders JG, Sitar S, Plummer SH, Yamshchikov G, Sarwar UN, Hu Z, Enama ME, Bailer RT, Koup RA, Schwartz RM, Akahata W, Nabel GJ, Mascola JR, Pierson TC, Graham BS, Ledgerwood JE; VRC 311 Study Team. Safety and tolerability of chikungunya virus-like particle vaccine in healthy adults: a phase 1 dose-escalation trial.  Lancet. 2014 Dec 6;384(9959):2046-52.

Seder RA, Chang LJ, Enama ME, Zephir KL, Sarwar UN, Gordon IJ, Holman LA, James ER, Billingsley PF, Gunasekera A, Richman A, Chakravarty S, Manoj A, Velmurugan S, Li M, Ruben AJ, Li T, Eappen AG, Stafford RE, Plummer SH, Hendel CS, Novik L, Costner PJ, Mendoza FH, Saunders JG, Nason MC, Richardson JH, Murphy J, Davidson SA, Richie TL, Sedegah M, Sutamihardja A, Fahle GA, Lyke KE, Laurens MB, Roederer M, Tewari K, Epstein JE, Sim BK, Ledgerwood JE, Graham BS, Hoffman SL; VRC 312 Study Team. Protection against malaria by intravenous immunization with a nonreplicating sporozoite vaccine. Science. 2013 Sep 20;341(6152):1359-65.

Ledgerwood JE, Zephir K, Hu Z, Wei CJ, Chang L, Enama ME, Hendel CS, Sitar S, Bailer RT, Koup RA, Mascola JR, Nabel GJ, Graham BS; VRC 310 Study Team. Prime-boost interval matters: a randomized phase 1 study to identify the minimum interval necessary to observe the H5 DNA influenza vaccine priming effect. J Infect Dis. 2013 Aug 1;208(3):418-22.

Last Updated March 30, 2015