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In a vaccine trial, assays for vaccine immunogenicity if performed locally will strengthen local site, can save costs and avoid hurdles associated with specimen transport. Here we report the optimization and validation of an Intracellular Cytokine Staining (ICS) assay which was undertaken in preparation for a phase I HIV vaccine trial conducted in Thailand. Intra-, and inter-operator variability were easily established. However, while attempting to set population cut offs for a positive response we found 4/36 (11%) high background responses of IFNγ(+) and/or IL-2(+) CD8(+) T cells (>1%) in normal healthy volunteers. The determinates of these unexpected responses were explored and minimized., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Counseling for participants in preventive HIV vaccine trials has been an area of continuing concern because of the need to address possible behavioral side effects (e.g., increased risk behavior because trial participants believe they may have received an active, effective vaccine) and social harms (e.g., discrimination in health care or employment because of vaccine-induced seropositivity on commercial HIV tests). Yet, the data on behavioral effects and social harms are limited and rather little detail has been provided regarding the counseling provided in current or past trials. This paper summarizes conceptual, cultural, and practical considerations in the development of a counseling program for HIV vaccine trials and provides examples from work done in the context of Phase I/II vaccine trials in Thailand.

An effective therapeutic HIV vaccine will not only benefit the HIV-infected person but will also provide invaluable information on effective immune response in designing or selecting a preventive vaccine. A phase II double-blind controlled clinical trial using HIV-1 immunogen (Remune) was undertaken in Thailand in 1995 in conjunction with phase III approval in the USA. In most instances, immune response to the virus was induced. The results from this study led to the extension of further trials over the following 4 years. At present, the Thai Food and Drug Administration (FDA) is in the process of reviewing the files on all information to assess the effectiveness of this therapeutic vaccine as well as reviewing the proposal to conduct a phase III trial to further confirm previous efficacy results from the phase II trials.

Factors believed to be predictive of retention through the recruitment and screening processes for preventive HIV trials were investigated in a large multisite phase I/II HIV vaccine trial in Thailand. Retention through recruitment was equal to or greater than in previous smaller trials with similar populations. The data suggested that recruitment proceeded in a stepwise manner with different influences at each step. Demographic and motivational variables were most important in predicting retention in making and keeping screening appointments. Altruistic or mixed altruistic and nonaltruistic motives were associated with greater retention. Laboratory/medical variables appeared to be the main influence on retention during screening, although some volunteers withdrew for different reasons. The frequent presence of mixed (altruistic and nonaltruistic) motives at initial contact suggests that motivation for trials is more complex than has been previously acknowledged.