A molecular epidemiological investigation of Ascaris on Unguja, Zanzibar using isoenyzme analysis, DNA barcoding and microsatellite DNA profiling.

Ascariasis is of public health importance on the islands of Zanzibar (Unguja and Pemba). To shed light on the molecular epidemiology of this parasite, 68 Ascaris worms, obtained from 14 individuals in four Ungujan villages, were examined by isoenzyme analysis (ISA), DNA barcoding and microsatellite DNA profiling. ISA revealed genetic variation, which was confirmed by DNA barcoding. Nineteen worms recovered from individuals in Uganda were included for comparison. Sixteen unique DNA barcodes were identified, 15 on Unguja and three in Uganda with two shared between. These two barcodes were found in all four Ungujan villages. Worms from Tumbatu-Jongowe, an isolated village on an islet off Unguja, seemed particularly diverse. Within our barcodes, three exact matches were found with Chinese Ascaris retrieved from pigs, which is perhaps surprising given the present rarity of these animals on Unguja. Microsatellite profiling and population genetic analysis revealed further genetic diversity within our samples although population sub-structuring within Unguja was minor in comparison to that between Unguja and Uganda. As African Ascaris has not been subjected to detailed molecular scrutiny, this new diversity represents an important piece in its evolutionary jigsaw and such population markers are informative in monitoring worm dynamics during ongoing control

Assessment of immune interference, antagonism, and diversion following human immunization with biallelic blood-stage malaria viral-vectored vaccines and controlled malaria infection.

Overcoming antigenic variation is one of the major challenges in the development of an effective vaccine against Plasmodium falciparum, a causative agent of human malaria. Inclusion of multiple Ag variants in subunit vaccine candidates is one strategy that has aimed to overcome this problem for the leading blood-stage malaria vaccine targets, that is, merozoite surface protein 1 (MSP1) and apical membrane Ag 1 (AMA1). However, previous studies, utilizing malaria Ags, have concluded that inclusion of multiple allelic variants, encoding altered peptide ligands, in such a vaccine may be detrimental to both the priming and in vivo restimulation of Ag-experienced T cells. In this study, we analyze the T cell responses to two alleles of MSP1 and AMA1 induced by vaccination of malaria-naive adult volunteers with bivalent viral-vectored vaccine candidates. We show a significant bias to the 3D7/MAD20 allele compared with the Wellcome allele for the 33 kDa region of MSP1, but not for the 19 kDa fragment or the AMA1 Ag. Although this bias could be caused by "immune interference" at priming, the data do not support a significant role for "immune antagonism" during memory T cell restimulation, despite observation of the latter at a minimal epitope level in vitro. A lack of class I HLA epitopes in the Wellcome allele that are recognized by vaccinated volunteers may in fact contribute to the observed bias. We also show that controlled infection with 3D7 strain P. falciparum parasites neither boosts existing 3D7-specific T cell responses nor appears to "immune divert" cellular responses toward the Wellcome allele

Analysis of human B-cell responses following ChAd63-MVA MSP1 and AMA1 immunization and controlled malaria infection.

Acquisition of non-sterilizing natural immunity to Plasmodium falciparum malaria has been shown in low transmission areas following multiple exposures. However, conflicting data from endemic areas suggest that the parasite may interfere with the induction of effective B-cell responses. To date, the impact of blood-stage parasite exposure on antigen-specific B cells has not been reported following controlled human malaria infection (CHMI). Here we analysed human B-cell responses in a series of Phase I/IIa clinical trials, which include CHMI, using candidate virus-vectored vaccines encoding two blood-stage antigens: merozoite surface protein 1 (MSP1) and apical membrane antigen 1 (AMA1). Previously vaccinated volunteers show boosting of pre-existing antigen-specific memory B-cell (mBC) responses following CHMI. In contrast, unvaccinated malaria-naive control volunteers developed an mBC response against MSP1 but not AMA1. Serum IgG correlated with the mBC response after booster vaccination but this relationship was less well maintained following CHMI. A significant reduction in peripheral MSP1-specific mBC was observed at the point of diagnosis of blood-stage infection. This was coincident with a reduction in peripheral blood B-cell subsets expressing CXCR3 and elevated serum levels of interferon-γ and CXCL9, suggesting migration away from the periphery. These CHMI data confirm that mBC and antibody responses can be induced and boosted by blood-stage parasite exposure, in support of epidemiological studies on low-level parasite exposure

Analysis of human B-cell responses following ChAd63-MVA MSP1 and AMA1 immunization and controlled malaria infection.

Acquisition of non-sterilizing natural immunity to Plasmodium falciparum malaria has been shown in low transmission areas following multiple exposures. However, conflicting data from endemic areas suggest that the parasite may interfere with the induction of effective B-cell responses. To date, the impact of blood-stage parasite exposure on antigen-specific B cells has not been reported following controlled human malaria infection (CHMI). Here we analysed human B-cell responses in a series of Phase I/IIa clinical trials, which include CHMI, using candidate virus-vectored vaccines encoding two blood-stage antigens: merozoite surface protein 1 (MSP1) and apical membrane antigen 1 (AMA1). Previously vaccinated volunteers show boosting of pre-existing antigen-specific memory B-cell (mBC) responses following CHMI. In contrast, unvaccinated malaria-naive control volunteers developed an mBC response against MSP1 but not AMA1. Serum IgG correlated with the mBC response after booster vaccination but this relationship was less well maintained following CHMI. A significant reduction in peripheral MSP1-specific mBC was observed at the point of diagnosis of blood-stage infection. This was coincident with a reduction in peripheral blood B-cell subsets expressing CXCR3 and elevated serum levels of interferon-γ and CXCL9, suggesting migration away from the periphery. These CHMI data confirm that mBC and antibody responses can be induced and boosted by blood-stage parasite exposure, in support of epidemiological studies on low-level parasite exposure

Pseudomonas aeruginosa infection in augmented care: the molecular ecology and transmission dynamics in four large UK hospitals

This is an accepted manuscript of an article published by Elsevier in Journal of Hospital Infection on 31/01/2021, available online: https://doi.org/10.1016/j.jhin.2021.01.020 The accepted version of the publication may differ from the final published version.Background Pseudomonas aeruginosa is a common opportunistic pathogen and molecular typing in outbreaks has linked patient acquisition to contaminated hospital water systems. Aim To elucidate the role of P. aeruginosa transmission rates in non-outbreak augmented care settings in the UK. Methods Over a 16-week period, all water outlets in augmented care units of four hospitals were sampled for P. aeruginosa and clinical isolates were collected. Outlet and clinical P. aeruginosa isolates underwent whole-genome sequencing (WGS), which with epidemiological data identified acquisition from water as definite (level 1), probable (level 2), possible (level 3), and no evidence (level 4). Findings Outlets were positive in each hospital on all three occasions: W (16%), X (2.5%), Y (0.9%) and Z (2%); and there were 51 persistently positive outlets in total. WGS identified likely transmission (at levels 1, 2 and 3) from outlets to patients in three hospitals for P. aeruginosa positive patients: W (63%), X (54.5%) and Z (26%). According to the criteria (intimate epidemiological link and no phylogenetic distance), approximately 5% of patients in the study ‘definitely’ acquired their P. aeruginosa from their water outlets in the intensive care unit. This study found extensive evidence of transmission from the outlet to the patients particularly in the newest hospital (W), which had the highest rate of positive outlets. Conclusions The overall findings suggest that water outlets are the most likely source of P. aeruginosa nosocomial infections in some settings, and that widespread introduction of control measures would have a substantial impact on infections.This study was funded by the Department of Health & Social Care (DHSC) Policy Research Programme (grant number PR-ST_1213-00007), and the NIHR Surgical Reconstruction and Microbiology Research Centre.Published versio

Active Objects for Coordinating BSP Computations (Short Paper)

International audienceAmong the programming models for parallel and distributed computing, one can identify two important families. The programming models adapted to data-parallelism, where a set of coordinated processes perform a computation by splitting the input data; and coordination languages able to express complex coordination patterns and rich interactions between processing entities. This article takes two successful programming models belonging to the two categories and puts them together into an effective programming model. More precisely, we investigate the use of active objects to coordinate BSP processes. We choose two paradigms that both enforce the absence of data-races, one of the major sources of error in parallel programming. This article explains why we believe such a model is interesting and provides a formal semantics integrating the notions of the two programming paradigms in a coherent and effective manner

Species-specific antifungal activity of blue light

Fungal pathogens represent a significant threat to immunocompromised patients or individuals with traumatic injury. Strategies to efficiently remove fungal spores from hospital surfaces and, ideally, patient skin thus offer the prospect of dramatically reducing infections in at-risk patients. Photodynamic inactivation of microbial cells using light holds considerable potential as a non-invasive, minimally destructive disinfection strategy. Recent data indicate that high-intensity blue light effectively removes bacteria from surfaces, but its efficacy against fungi has not been fully tested. Here we test a wide range of fungi that are pathogenic to humans and demonstrate that blue light is effective against some, but not all, fungal species. We additionally note that secondary heating effects are a previously unrecognized confounding factor in establishing the antimicrobial activity of blue light. Thus blue light holds promise for the sterilization of clinical surfaces, but requires further optimization prior to widespread use.</p