Ex vivo functional immunoassays such as ELISpot and intracellular cytokine staining (ICS) by flow cytometry are crucial tools in vaccine development both in the identification of novel immunogenic targets and in the immunological assessment of samples from clinical trials. Cryopreservation and subsequent thawing of PBMCs via validated processes has become a mainstay of clinical trials due to processing restrictions inherent in the disparate location and capacity of trial centres, and also in the need to standardize biological assays at central testing facilities. Logistical and financial requirement to batch process samples from multiple study timepoints are also key. We used ELISpot and ICS assays to assess antigen-specific immunogenicity in blood samples taken from subjects enrolled in a phase II malaria heterologous prime-boost vaccine trial and showed that the freeze thaw process can result in a 3–5-fold reduction of malaria antigen-specific IFNγ-producing CD3+CD4+ effector populations from PBMC samples taken post vaccination. We have also demonstrated that peptide responsive CD8+ T cells are relatively unaffected, as well as CD4+ T cell populations that do not produce IFNγ. These findings contribute to a growing body of data that could be consolidated and synthesised as guidelines for clinical trials with the aim of increasing the efficiency of vaccine development pipelines.
Background PrEP literacy is influenced by many factors including the types of information available and how it is interpreted. The level of PrEP literacy may influence acceptability and uptake. Methods We conducted 25 in-depth interviews in a HIV vaccine trial preparedness cohort study. We explored what participants knew about PrEP, sources of PrEP knowledge and how much they know about PrEP. We used the framework approach to generate themes for analysis guided by the Social Ecological Model and examined levels of PrEP literacy using the individual and interpersonal constructs of the SEM. Results We found that PrEP awareness is strongly influenced by external factors such as social media and how much participants know about HIV treatment and prevention in the local community. However, while participants highlighted the importance of the internet/social media as a source of information about PrEP they talked of low PrEP literacy in their communities. Participants indicated that their own knowledge came as a result of joining the HIV vaccine trial preparedness study. However, some expressed doubts about the effectiveness of the drug and worried about side effects. Participants commented that at the community level PrEP was associated with being sexually active, because it was used to prevent the sexual transmission of HIV. As a result, some participants commented that one could feel judged by the health workers for asking for PrEP at health facilities in the community. Conclusion The information collected in this study provided an understanding of the different layers of influence around individuals that are important to address to improve PrEP acceptability and uptake. Our findings can inform strategies to address the barriers to PrEP uptake, particularly at structural and community levels. Trial registration https://clinicaltrials.gov/ct2/show/NCT04066881
Introduction Current interferon-gamma (IFN-γ) release assays (IGRAs) are not sufficiently sensitive to be used as a "rule-out" test for tuberculosis (TB). Antigen-specific gene expression of chemokines downstream of, and amplified by, IFN-γ might demonstrate such sensitivity, and can be performed with very small volumes of blood. 1 Here we assess the performance and sensitivity of two IFN-γdependent gene expression platforms in the peripheral blood mononuclear cells of individuals with and without TB. Methods 23 individuals with active TB, 12 individuals with latent TB infection (LTBI), and 18 controls had simultaneous IFN-γ ELISpot assays and qRTPCR of CXCL-9 and CXCL-10, following stimulation with the immunodominant antigens ESAT-6, CFP-10 and EspC (6 gene expression assays in total). Test performances of the 6 gene expression assays were compared to the ELISpot. Results Gene expression of CXCL-9 and CXCL-10 was antigen specific, correlating well with each other and with the IFN-γ ELISpot (Spearman Rank Correlations ranging from r=0.648 to 0.74). Gene expression of either was not significantly different between those with active TB and LTBI. Receiver-operating characteristic curves indicated good test performances for all the gene expression assays (AUC ranging from 0.918 to 0.959) and agreements between the ELISpot and gene expression platforms was good (κ statistic ranging from 0.403-0.496). After constructing cutoffs for sensitivity for individual antigens, with cutoffs for specificity matching or exceeding that of the IFN-γ ELISpot, the sensitivity of TB diagnosis with gene expression was superior to ELISpot in 5 out of the 6 assays, although these differences were not statistically significant. Sensitivity was equivalent when antigens were combined, as in the commercially available T-Spot ® .TB. Conclusions These pilot data indicate that gene expression of IFN-γ-dependent cytokines is a robust, sensitive and specific method of TB diagnosis, and carries potential to be a more sensitive platform that the current gold standard-IFN-γ ELISpot. Larger studies with appropriate power are now required in similar populations to investigate this approach definitively. References
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.