Unraveling the Impact of Malaria Exposure Before Birth

Lars Hviid discusses a research article in PLoS Medicine that explores whether prenatal exposure to malaria is associated with increased susceptibility to malarial infection and anemia in infancy

Vaccine safety issues at the turn of the 21st century

Global gains in vaccination coverage during the early 21st century have been threatened by the emergence of antivaccination groups that have questioned the effectiveness of vaccines to generate public distrust of vaccines and immunisation programmes. This manuscript summarises six key topics that have been at the centre of global discussions on vaccine safety during the early 21st century: thiomersal in multi-dose non-live vaccines, aluminium adjuvants used with several non-live vaccines, autism and auto-immune conditions as possible consequences of vaccination, a risk of immune overload with increasing numbers of vaccinations, and detrimental non-specific effects (NSEs) of vaccination. For each topic, we describe the hypothesis behind the public concern, the evidence reviewed by the WHO's Global Advisory Committee for Vaccine Safety (GACVS) during 1999-2019, and any significant new data that has emerged since GACVS conclusions were made. Although the scientific evidence on these issues overwhelmingly supports the safety of vaccines, communication messages to caregivers and providers need to condense and convey scientific information in an appropriate way to address concerns contributing to vaccine distrust. In addition, there is need for further studies specifically designed to address both positive and negative NSE of vaccination. The role of GACVS will be increasingly important in evaluating the evidence and engaging the global community in promoting and assuring the safety of vaccines in the decades to come as we move into an era in which we use new vaccination platforms, antigens and formulations

Selective activation of TCR-γδ+ cells in endemic Burkitt's lymphoma

<p>Abstract</p> <p>Background</p> <p>The overlap in geographical distribution of <it>Plasmodium falciparum </it>malaria and endemic Burkitt's lymphoma (eBL) – an aggressive Epstein-Barr virus (EBV)-associated B-cell tumour occurring almost exclusively in the tropics – strongly suggests a link between the two diseases. It is suspected that the polyclonal B-cell activation in <it>P. falciparum </it>malaria may precipitate a breakdown in homeostatic T-cell control of EBV-immortalized B-cell proliferation. Previous studies have suggested that a particular T-cell subset, characterized by expression of V<it>δ</it>1⁺<it>γδ </it>T-cell receptors, is important for maintaining B-cell homeostasis, both in <it>P. falciparum</it>- exposed populations and in individuals subject to polyclonal B-cell activation of other aetiology. The objective of the present study was, therefore, to characterize lymphocyte phenotypes and to investigate possible differences in T-cell subset composition and activation status in <it>P. falciparum</it>-exposed Ghanaian children with and without eBL.</p> <p>Methods</p> <p>Venous blood samples in heparin from 21 eBL patients (mean age: 7.0 years; range: 3–11 years), referred to the Burkitt's Tumour Centre at Korle-Bu Teaching Hospital, Accra and 15 healthy, age and sex matched children, were stained with fluorescein isothiocyanate (FITC)-, phycoerythrin (PE)-, R-phycoerythrin (RPE)- and RPE-Cy5-conjugated antibodies (CD3, CD4, CD8, CD25, CD69, CD95, HLA-DR, TCR-<it>γδ</it>, V<it>δ</it>1, V<it>δ</it>3, V<it>γ</it>9 and B-cells) and acquired on a flow cytometer.</p> <p>Results</p> <p>A reduction in the proportion of CD3⁺cells in eBL patients, due mainly to perturbations among TCR-<it>γδ</it>⁺cells was observed. In contrast, the proportions of CD4⁺or CD8⁺cells were relatively unaffected, as were the mean numbers of peripheral blood mononuclear cells.</p> <p>Conclusion</p> <p>Selective changes in numbers and activation status of TCR-<it>γδ</it>⁺cells occurs in Ghanaian children with eBL, a pattern which is similar to <it>P. falciparum</it>-induced changes. The data supports the hypothesis of a regulatory role for V<it>δ</it>1⁺TcR-<it>γδ </it>T-cells in maintaining B-cell homeostasis and provides insights into the pathogenesis of eBL.</p

Overcoming data scarcity of Twitter: using tweets as bootstrap with application to autism-related topic content analysis

Notwithstanding recent work which has demonstrated the potential of using Twitter messages for content-specific data mining and analysis, the depth of such analysis is inherently limited by the scarcity of data imposed by the 140 character tweet limit. In this paper we describe a novel approach for targeted knowledge exploration which uses tweet content analysis as a preliminary step. This step is used to bootstrap more sophisticated data collection from directly related but much richer content sources. In particular we demonstrate that valuable information can be collected by following URLs included in tweets. We automatically extract content from the corresponding web pages and treating each web page as a document linked to the original tweet show how a temporal topic model based on a hierarchical Dirichlet process can be used to track the evolution of a complex topic structure of a Twitter community. Using autism-related tweets we demonstrate that our method is capable of capturing a much more meaningful picture of information exchange than user-chosen hashtags.Comment: IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining, 201

Modeling malaria infection and immunity against variant surface antigens in Príncipe Island, West Africa

After remarkable success of vector control campaigns worldwide, concerns about loss of immunity against Plasmodium falciparum due to lack of exposure to the parasite are relevant since an increase of severe cases in less immune individuals is expected. We present a mathematical model to investigate the impact of reducing exposure to the parasite on the immune repertoire against P. falciparum erythrocyte membrane protein 1 (PfEMP1) variants. The model was parameterized with data from Príncipe Island, West Africa, and applied to simulate two alternative transmission scenarios: one where control measures are continued to eventually drive the system to elimination; and another where the effort is interrupted after 6 years of its initiation and the system returns to the initial transmission potential. Population dynamics of parasite prevalence predict that in a few years infection levels return to the pre-control values, while the re-acquisition of the immune repertoire against PfEMP1 is slower, creating a window for increased severity. The model illustrates the consequences of loss of immune repertoire against PfEMP1 in a given setting and can be applied to other regions where similar data may be available