Limited polymorphism in Plasmodium falciparum ookinete surface antigen, von Willebrand factor A domain-related protein from clinical isolates

BACKGROUND: As malaria becomes increasingly drug resistant and more costly to treat, there is increasing urgency to develop effective vaccines. In comparison to other stages of the malaria lifecycle, sexual stage antigens are under less immune selection pressure and hence are likely to have limited antigenic diversity. METHODS: Clinical isolates from a wide range of geographical regions were collected. Direct sequencing of PCR products was then used to determine the extent of polymorphisms for the novel Plasmodium falciparum sexual stage antigen von Willebrand Factor A domain-related Protein (PfWARP). These isolates were also used to confirm the extent of diversity of sexual stage antigen Pfs28. RESULTS: PfWARP was shown to have non-synonymous substitutions at 3 positions and Pfs28 was confirmed to have a single non-synonymous substitution as previously described. CONCLUSION: This study demonstrates the limited antigenic diversity of two prospective P. falciparum sexual stage antigens, PfWARP and Pfs28. This provides further encouragement for the proceeding with vaccine trials based on these antigens

Mannose-binding lectin genotypes: lack of association with susceptibility to thoracic empyema

<p>Abstract</p> <p>Background</p> <p>The role of the innate immune protein mannose-binding lectin (MBL) in host defence against severe respiratory infection remains controversial. Thoracic empyema is a suppurative lung infection that arises as a major complication of pneumonia and is associated with a significant mortality. Although the pathogenesis of thoracic empyema is poorly understood, genetic susceptibility loci for this condition have recently been identified. The possible role of MBL genotypic deficiency in susceptibility to thoracic empyema has not previously been reported.</p> <p>Methods</p> <p>To investigate this further we compared the frequencies of the six functional <it>MBL </it>polymorphisms in 170 European individuals with thoracic empyema and 225 healthy control individuals.</p> <p>Results</p> <p>No overall association was observed between MBL genotypic deficiency and susceptibility to thoracic empyema (2 × 2 Chi square = 0.02, <it>P </it>= 0.87). Furthermore, no association was seen between MBL deficiency and susceptibility to the Gram-positive or pneumococcal empyema subgroups. MBL genotypic deficiency did not associate with progression to death or requirement for surgery.</p> <p>Conclusions</p> <p>Our results suggest that MBL genotypic deficiency does not associate with susceptibility to thoracic empyema in humans.</p

Antibodies elicited in adults by a primary Plasmodium falciparum blood-stage infection recognize different epitopes compared with immune individuals

<p>Abstract</p> <p>Background</p> <p>Asexual stage antibody responses following initial <it>Plasmodium falciparum </it>infections in previously healthy adults may inform vaccine development, yet these have not been as intensively studied as they have in populations from malaria-endemic areas.</p> <p>Methods</p> <p>Serum samples were collected over a six-month period from twenty travellers having returned with falciparum malaria. Fourteen of these were malaria-naïve and six had a past history of one to two episodes of malaria. Antibodies to seven asexual stage <it>P. falciparum </it>antigens were measured by ELISA. Invasion inhibitory antibody responses to the 19kDa fragment of merozoite surface protein 1 (MSP1₁₉) were determined.</p> <p>Results</p> <p>Short-lived antibody responses were found in the majority of the subjects. While MSP1₁₉antibodies were most common, MSP1 block 2 antibodies were significantly less frequent and recognized conserved domains. Antibodies to MSP2 cross-reacted to the dimorphic allelic families and anti-MSP2 isotypes were not IgG3 skewed as shown previously. MSP1₁₉invasion inhibiting antibodies were present in 9/20 patients. A past history of malaria did not influence the frequency of these short-lived, functional antibodies (p = 0.2, 2-tailed Fisher's exact test).</p> <p>Conclusion</p> <p>Adults infected with <it>P. falciparum </it>for the first time, develop relatively short-lived immune responses that, in the case of MSP1₁₉, are functional. Antibodies to the polymorphic antigens studied were particularly directed to allelic family specific, non-repetitive and conserved determinants and were not IgG subclass skewed. These responses are substantially different to those found in malaria immune individuals.</p

Low pre-transplant levels of mannosebinding lectin are associated with viral infections and mortality after haematopoietic allogeneic stem cell transplantation

Background: Mannose-binding lectin (MBL) is a key component of innate immunity. Low serum MBL levels, related to promoter polymorphism and structural variants, have been associated with an increased risk of infection. The aim of this work was to analyse the incidence and severity of infections and mortality in relation to the MBL2 genotype and MBL levels in patients underwent allogeneic haematopoietic stem cell transplantation (Allo-HSCT). Results: This was a prospective cohort study of 72 consecutive patients underwent Allo-HSCT between January 2007 and June 2009 in a tertiary referral centre. Three periods were considered in the patients? follow-up: the early period (0?30 days after Allo-HSCT), the intermediate period (30?100 days after Allo-HSCT) and the late period (> 100 days after Allo-HSCT). A commercial line probe assay for MBL2 genotyping and an ELISA Kit were used to measure MBL levels. A total of 220 episodes of infection were collected in the 72 patients. No association between donor or recipient MBL2 genotype and infection was found. The first episode of infection presented earlier in patients with pre-transplant MBL levels of < 1000 ng/ml (median 6d vs 8d, p = 0.036). MBL levels < 1000 ng/ml in the pre-transplant period (risk ratio (RR) 2.48, 95% CI 1.00?6.13), neutropenic period (0?30 days, RR 3.28, 95% CI 1.53?7.06) and intermediate period (30?100 days, RR 2.37, 95% CI 1.15?4.90) were associated with increased risk of virus infection. No association with bacterial or fungal disease was found. Mortality was associated with pre-transplant MBL levels < 1000 ng/ml (hazard ratio 5.55, 95% CI 1.17?26.30, p = 0.03) but not with MBL2 genotype. Conclusions: Patients who underwent Allo-HSCT with low pre-transplant MBL levels presented the first episode of infection earlier and had an increased risk of viral infections and mortality in the first 6 months post-transplant. Thus, pre-transplant MBL levels would be important in predicting susceptibility to viral infections and mortality and might be considered a biomarker to be included in the pre-transplantation risk assessment.This work was supported by grants from the Fondo de Investigaciones Sanitarias (Ministry of Health of Spain) PI04/0492 to MC Fariñas and Instituto de Investigación Sanitaria Valdecilla (IDIVAL) API 06/01. The content of the paper is solely the responsibility of the authors and does not necessarily represent the official views. The funding body was not involved in the design of the study, collection or analysis of the data, interpretation of the data, or in the writing of the manuscript

A novel malaria vaccine candidate antigen expressed in Tetrahymena thermophila

Development of effective malaria vaccines is hampered by the problem of producing correctly folded Plasmodium proteins for use as vaccine components. We have investigated the use of a novel ciliate expression system, Tetrahymena thermophila, as a P. falciparum vaccine antigen platform. A synthetic vaccine antigen composed of N-terminal and C-terminal regions of merozoite surface protein-1 (MSP-1) was expressed in Tetrahymena thermophila. The recombinant antigen was secreted into the culture medium and purified by monoclonal antibody (mAb) affinity chromatography. The vaccine was immunogenic in MF1 mice, eliciting high antibody titers against both N- and C-terminal components. Sera from immunized animals reacted strongly with P. falciparum parasites from three antigenically different strains by immunofluorescence assays, confirming that the antibodies produced are able to recognize parasite antigens in their native form. Epitope mapping of serum reactivity with a peptide library derived from all three MSP-1 Block 2 serotypes confirmed that the MSP-1 Block 2 hybrid component of the vaccine had effectively targeted all three serotypes of this polymorphic region of MSP-1. This study has successfully demonstrated the use of Tetrahymena thermophila as a recombinant protein expression platform for the production of malaria vaccine antigens

Genomic analysis of the function of the transcription factor gata3 during development of the Mammalian inner ear

We have studied the function of the zinc finger transcription factor gata3 in auditory system development by analysing temporal profiles of gene expression during differentiation of conditionally immortal cell lines derived to model specific auditory cell types and developmental stages. We tested and applied a novel probabilistic method called the gamma Model for Oligonucleotide Signals to analyse hybridization signals from Affymetrix oligonucleotide arrays. Expression levels estimated by this method correlated closely (p<0.0001) across a 10-fold range with those measured by quantitative RT-PCR for a sample of 61 different genes. In an unbiased list of 26 genes whose temporal profiles clustered most closely with that of gata3 in all cell lines, 10 were linked to Insulin-like Growth Factor signalling, including the serine/threonine kinase Akt/PKB. Knock-down of gata3 in vitro was associated with a decrease in expression of genes linked to IGF-signalling, including IGF1, IGF2 and several IGF-binding proteins. It also led to a small decrease in protein levels of the serine-threonine kinase Akt2/PKB beta, a dramatic increase in Akt1/PKB alpha protein and relocation of Akt1/PKB alpha from the nucleus to the cytoplasm. The cyclin-dependent kinase inhibitor p27(kip1), a known target of PKB/Akt, simultaneously decreased. In heterozygous gata3 null mice the expression of gata3 correlated with high levels of activated Akt/PKB. This functional relationship could explain the diverse function of gata3 during development, the hearing loss associated with gata3 heterozygous null mice and the broader symptoms of human patients with Hearing-Deafness-Renal anomaly syndrome

A Complex Cell Division Machinery Was Present in the Last Common Ancestor of Eukaryotes

Background: The midbody is a transient complex structure containing proteins involved in cytokinesis. Up to now, it has been described only in Metazoa. Other eukaryotes present a variety of structures implied in the last steps of cell division, such as the septum in fungi or the phragmoplast in plants. However, it is unclear whether these structures are homologous (derive from a common ancestral structure) or analogous (have distinct evolutionary origins). Recently, the proteome of the hamster midbody has been characterized and 160 proteins identified. Methodology/Principal Findings: Using phylogenomic approaches, we show here that nearly all of these 160 proteins (95%) are conserved across metazoan lineages. More surprisingly, we show that a large part of the mammalian midbody components (91 proteins) were already present in the last common ancestor of all eukaryotes (LECA) and were most likely involved in the construction of a complex multi-protein assemblage acting in cell division. Conclusions/Significance: Our results indicate that the midbodies of non-mammalian metazoa are likely very similar to the mammalian one and that the ancestor of Metazoa possessed a nearly modern midbody. Moreover, our analyses support the hypothesis that the midbody and the structures involved in cytokinesis in other eukaryotes derive from a large and complex structure present in LECA, likely involved in cytokinesis. This is an additional argument in favour of the idea of a comple