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Niel T. Constantine

Niel T. Constantine Ph.D.

Academic Title: Professor
Primary Appointment: Pathology
Additional Title(s): Director, Clinical Immunology
Location: IHV, S215
Phone: (410) 706-2788
Fax: (410) 706-2789
Lab: (410) 706-2214

Personal History:

Dr. Niel T. Constantine, a professor in the Department of Pathology, possesses 30 years of experience in the medical diagnostic arena, acts frequently as an international consultant for laboratory strengthening activities in many countries, and has a productive track record with extramural funding and publications. After obtaining a degree in Medical Technology, he completed his Ph.D. in Pathology at the University of Maryland where he has remained. During this time, he spent 3 years at the U.S. Naval Medical Research Unit #3 in Cairo Egypt where he established and headed a laboratory for HIV surveillance that became a WHO Collaborating Centre for HIV in the Eastern Mediterranean Region. When returning to the University in 1990, he was appointed Director of the Clinical Immunology Laboratory at the UM Medical Systems Hospital where a variety of testing is performed, including all HIV serologic testing and CD4 levels for HIV patient care. During 1993, Dr. Constantine was recruited to Geneva to work with the Global AIDS Programme in the Diagnostics Unit for establishing research protocols in a number of countries, and addressing issues in global diagnostics for HIV. Since that time, Dr. Constantine established the Laboratory of Viral Diagnostics, a strong research unit at the Institute of Human Virology that provides support for several divisions and conducts developmental test research. He and his staff are currently active in providing laboratory capability building and quality assurance for the PEPFAR program in Nigeria.


  • Ph.D. – Pathology, University of Maryland School of Medicine, Baltimore, 1981
  • B.S. – Medical Technology, University of Maryland, Baltimore, 1974
  • B.A. – Psychology, University of Maryland Baltimore County, 1973

Honors and Awards

In 2005, Dr. Constantine received the Innovatorf the Year Award from The Daily Record for his work in the development of a test for detection of prions in blood.

Research Interests:

The Laboratory of Viral Diagnostics at the Institute of Human Virology provides serologic and molecular testing capabilities, performs research activities for the development of test technology, provides training for international students, and supports a variety of ancillary activities including sample archiving, quality assurance support, and clinical trials. The staff include persons with Masters degrees in Molecular Biology, a Ph.D., and two laboratory assistants. Efforts are directed toward the development of a variety of novel technologies aimed at increasing sensitivity, simplifying procedures, and developing test technologies for resource-limited facilities in developing countries. Currently, Dr. Constantine is principal investigator for activities supported through grants from the US government, a commercial company for a FDA clinical trial for a rapid HIV test, and a grant from the Centers for Disease Control for the assessment of HIV testing algorithms. Recent grants included two from NIH for the ultra-sensitive detection of biothreat agents and development of a test to determine recent HIV infection, one from the Department of Defense for development of a blood test to detect prion protein, and industrial support for several FDA clinical trials involving HIV tests. The laboratory has been a clinical site for all 6 FDA-licensed rapid HIV tests. A major emphasis in the Laboratory of Viral Diagnostics includes new test development for the ultrasensitive detection of HIV proteins. Methods are being developed that incorporate signal amplification strategies for routine protein and antigen detection, both in high throughput and rapid/simple test configurations. Immuno-PCR that couples molecular and serologic capture methods is being explored with unique modifications of basic concepts to offer reduced background with more simplified real-time detection methods. Theoretical potentials allow for the detection of HIV p24 antigen earlier than that offered at the current level of 50 copies of HIV RNA by PCR, and the detection of prion protein at pre-symptomatic levels. Other signal amplification strategies, appropriate for resource-limited countries, include those for increasing colorimetric endpoints for both membrane-based assay configurations as well as on microsphere-coated particles that utilize battery-operated platforms. Other activities include development and assessment of sensitive/less sensitive assays to offer more efficient ways to enroll recently-infected persons into intervention programs.

Consulting Activities:

Major consultant activities include those from the World Bank, USAID, and the WHO for laboratory strengthening in the countries of Egypt, Thailand, Uganda, India, the Ukraine, Indonesia, and the Philippines, all of which resulted in a number of demonstrable improvements in laboratory expertise and capabilities. Dr. Constantine has also been recruited by the WHO to assist with the Global Alliance for Vaccine Initiative (GAVI), and has worked closely with the CDC for HIV testing activities in Nigeria.

Other Activities:

Dr. Constantine has served on many University committees, has provided editorial assistance for over 10 journals, has recently mentored two Ph.D. students and two Masters students, and performs laboratory inspections for the College of American Pathologists.


Dr. Constantine’s efforts have resulted in the publication of over 130 articles, including two books, 10 book chapters and nearly 200 abstracts, most of which describe new technologies and their applications. Of particular note is his book on Retroviral Testing and Quality Assurance (2005) that is used in laboratories throughout the world. The non-profit, 700 page book, is targeted to laboratory personnel, program managers, and international agencies.

Selected Publications

Highsmith, W.E., Constantine, N.T., and Friedman, K. F.: Molecular diagnostics, (Chapter 48). In: Kaplan, L., Pesche, A., and Kazmierszak (Eds.). Clinical Chemistry, 4th Ed. NY: Mosby, 2003

Constantine, N.T. and Lana, L.: Immunoassays for the diagnosis of infectious diseases. In: Murray et al. (Eds.), Manual of Clinical Microbiology, 8th Ed., ASM Press, p. 218-233, 2003

Constantine, N.T., Sill, A.M., Jack, N., Kreisel, K., Edwards, J., Cafarella, T., Smith, H., Bartholomew, C., Cleghorn, F., and Blattner, W.A.: Improved classification of recent HIV-1 infection by employing a two-stage sensitive/less sensitive test strategy. JAIDS, 32: 94-103, 2003

Barletta, J.M., Edelman, D.C., and Constantine, N.T. : Lowering the detection limits of HIV-1 viral load using real-time immuno-PCR for HIV-1 p24 antigen. American Journal of Clinical Pathology, 122:20-27, 2004

Constantine, N.T. and Zink, H.: HIV testing technologies after 2 decades of evolution. Indian Journal of Medical Research, 121:1-12, 2005

Ketema, F., Zink, H., Croxton, T., Kreisel, K., and Constantine, N.T. : A 10-minute USFDA approved HIV test. Expert Review of Molecular Diagnostics, 5:135-143, 2005

Barletta, J.M., Edelman, D.C., Highsmith, W.E., and Constantine, N.T.: Detection of 10 infectious units of pathologic prion protein (PRPSc) from scrapie infected hamster brain homogenates using real-time immuno-PCR. Journal of Virological Methods, 127:154-164, 2005

Constantine, N.T., Kabat, W., and Zhao, R.Y.: Update on the laboratory diagnosis and monitoring of HIV infection. Cell Research, 15(11-12):870-6, 2005

Constantine, N.T., Saville, R., and Dax, E.: Retroviral Testing and Quality Assurance: Essentials for Laboratory Diagnosis. Malloy Printers, 2005

Constantine, N.T. and Zhao, R.Y.: Molecular-based laboratory testing and monitoring for human immunodeficiency virus infections. Clinical Laboratory Science, 18(4):263-70, 2005

Sill, A.M., Kreisel, K., Deeds, B.G., Wilson, C.M., Constantine, N.T., Peralta, L., & the Adolescent Trials Network (ATN) for HIV/AIDS Intervention. Calibration and validation of an oral fluid-based S/LS assay to distinguish recent from established HIV-1 infection. Journal of Clinical Laboratory Analysis, 21:40-45, 2007

Sajadi, M., Heredia, A., Le, N., Chan-Tack, K., Constantine, N., DeVico, A., & Redfield, R. HIV-1 natural viral suppressors: Control of viral replication in the absence of therapy. AIDS, 21:517-528, 2007

Hong, L., Ketema, F., Sill, A., Kreisel, K., Cleghorn, F.R., & Constantine, N.T. A simple and inexpensive particle agglutination test to distinguish recent and established HIV-1 infection. International Journal of Infectious Disease, 11: 459-465, 2007

Nadai, Y., Eyzaguirre, L.M., Constantine, N.T., Sill, A.M., cleghorn, F., Blattner, W.A., Carr, J.K. Protocol for nearly full-length sequencing of HIV-1 RNA from plasma. Plos One: 1: 1-6, 2008

Barletta, J., Bartolome, A., Constantine, N.T. Immunomagnetic quantitative immuno-PCR for detection of less than one HIV-1 virion. J. Virol. Meth., 157: 122-132, 2009.

Sill, A.M., Constantine, N.T., Wilson, C.M., Peralta, L., et al.: Demographic profiles of newly acquired HIV infections among adolescents and young adults in the U.S. J. Adol. Health, In press, 2009.

Sajadi, M.M., Constantine, N.T., Mann, D.L., Charurat, M., Dadzan, E., Kadlecik, P., Redfield, R.R. Epidemiologic characteristics and natural history of HIV-1 natural viral suppressors. JAIDS, 50: 403-408, 2009.

Wesolowski, L., Sanchez, T.H., Duncan, M., Ethridge, S., Constantine, N.T., Ketema, F., Sullivan, P. Evaluation of oral fluid enzyme immunoassay for confirmation of a positive rapid HIV test result. Clin. Vac. Immuno. In press, 2009.

Sajadi, MM, Kuruppu, J, Constantine, NT, Redfield, R. High rate of HIV misdiagnosis among persons with undetectable HIV viral loads. AIDS, in press, 2009.

Charurat, M, Delaney, K, Ahmed, S, Villalba-Diebold, P, Aliyu, G, Constantine, NT, Onoja, A, Vertefeuille, J, Blattner, W, Nasidi, A. HIV testing and access to care needs of most at risk populations in Nigeria. AIDS, in press, 2009.