Browsing by Author "Stevens, Gwynneth"

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    Concordant Proficiency in Measurement of T-Cell Immunity in Human Immunodeficiency Virus Vaccine Clinical Trials by Peripheral Blood Mononuclear Cell and Enzyme-Linked Immunospot Assays in Laboratories from Three Continents
    (Clinical and vaccine immunology, 2009-02) Boaz, Mark J.; Hayes, Peter; Tarragona, Tony; Seamons, Laura; Cooper, Andrew; Birungi, Josephine; Kitandwe, Paul; Semaganda, Aloysius; Kaleebu, Pontiano; Stevens, Gwynneth; Anzala, Omu; Farah, Bashir; Ogola, Simon; Indangasi, Jackton; Mhlanga, Patrick; Eeden, Melanie Van; Thakar, Madhuri; Pujari, Ashwini; Mishra, Shadri; Goonetilleke, Nilu; Moore, Stephen; Mahmoud, Abdul; Sathyamoorthy, Pattabiraman; Mahalingam, Jayashri; Narayanan, Paranji R.; Ramanathan, Vadakkuppattu D.; Cox, Josephine H.; Dally, Len; Gill, Dilbinder K.; Gilmour, Jill
    The gamma interferon (IFN-_) enzyme-linked immunospot (ELISPOT) assay is used routinely to evaluate the potency of human immunodeficiency virus (HIV) vaccine candidates and other vaccine candidates. In order to compare candidates and pool data from multiple trial laboratories, validated standardized methods must be applied across laboratories. Proficiency panels are a key part of a comprehensive quality assurance program to monitor inter- and intralaboratory performance, as well as assay performance, over time. Seven International AIDS Vaccine Initiative-sponsored trial sites participated in the proficiency panels described in this study. At each laboratory, two operators independently processed identical sample sets consisting of frozen peripheral blood mononuclear cell (PBMC) samples from different donors by using four blind stimuli. PBMCM recovery and viability after overnight resting and the IFN-_ ELISPOT assay performance were assessed. All sites demonstrated good performance in PBMC thawing and resting, with a median recovery of 78% and median viability of 95%. The laboratories were able to detect similar antigen-specific T-cell responses, ranging from 50 to >3,000 spot-forming cells per million PBMC. An approximate range of a half log in results from operators within or across sites was seen in comparisons of antigen-specific responses. Consistently low background responses were seen in all laboratories. The results of these proficiency panels demonstrate the ability of seven laboratories, located across three continents, to process PBMC samples and to rank volunteers with differential magnitudes of IFN-_ ELISPOT responses. These findings also illustrate the ability to standardize the IFN-_ ELISPOT assay across multiple laboratories when common training methods, reagents such as fetal calf serum, and standard operating procedures are adopted. These results are encouraging for laboratories that are using cell-based immunology assays to test HIV vaccines and other vaccines.
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    Setting up a Standardized Peripheral Blood Mononuclear Cells Processing Laboratory to Support Multi-center HIV/AIDS Vaccine and Intervention Trials.
    (Labmedicine, 2011) Njai, Harr Freeya; Gombe, Ben; Khamis, Tomusange; Birungi, Josephine; Ruzagira, Eugene; Admassu, Dareskedar; Tarragona-Fiol, Tony; Porter, Kholoud; Stevens, Gwynneth; Mugisha, Joseph; Gilmour, Jill; Kamali, Anatoli; Kaleebu, Pontiano
    Despite infrastructure and capacity challenges in Africa, significant development has been made in the number of laboratories supporting immunological and safety studies required for large-scale HIV/AIDS vaccine or intervention trials. In Uganda, cohorts participating in HIV intervention trials are often recruited from rural areas. To avoid transporting samples from intervention trial areas over long distances (120 km) to central laboratories in Entebbe, we set up a standardized peripheral blood mononuclear cells (PBMCs) processing laboratory at a field station in Masaka, southwest Uganda. The laboratory was well equipped and enrolled into the International AIDS Vaccine Initiative (IAVI) Quality Assurance (QA) program. Staff was trained in laboratory techniques and Good Clinical Laboratory Practice (GCLP). The laboratory received IAVI and GCLP accreditation in 2008. In this paper we describe the process and achievements of measures taken to overcome challenges, to build staff capacity, and to optimize the quality of the cells yielded.