Cellular responses to <Emphasis Type="Italic">Plasmodium falciparum</Emphasis> erythrocyte membrane protein-1: use of relatively conserved synthetic peptide pools to determine CD4 T cell responses in malaria-exposed individuals in Benin,West Africa

Background

Plasmodium falciparum erythrocyte membrane protein-1, a variant antigen of the malaria parasite, is potentially a target for the immune response. It would be important to determine whether there are CD4 T cells that recognise conserved regions. However, within the relatively conserved region, there is variation. It is not possible to test T cell responses from small field samples with all possible peptides.

Methods

We have aligned sequences that are relatively conserved between several PfEMP1 molecules, and chosen a representative sequence similar to most of the PfEMP1 variants. Using these peptides as pools representing CIDRα, CIDRβ and DBLβ-δ domains, DBLα domain, and EXON 2 domain of PfEMP1, we measured the CD4 T cell responses of malaria-exposed donors from Benin, West Africa by a FACS based assay.

Results

All the three peptide pools elicited a CD4 T cell response in a proportion of malaria-exposed and non-exposed donors. CD4 T cell proliferation occurs at a relatively higher magnitude to peptide pools from the DBLα and EXON 2 in the malaria-exposed donors living in Benin than in the UK malaria-unexposed donors.

Conclusions

These findings suggest that an immunological recall response to conserved peptides of a variant antigen can be measured. Further testing of individual peptides in a positive pool will allow us to determine those conserved sequences recognised by many individuals. These types of assays may provide information on conserved peptides of PfEMP1 which could be useful for stimulating T cells to provide help to P. falciparum specific B cells.

     

Seasonal occurrence and ecological aspects of Afrodiplozoon polycotyleus (Monogenea: Diplozoidae) from the gills of three cyprinids from the Nwanedi-Luphephe dams,South Africa

The effect of seasonal changes and ecological aspects of Afrodiplozoon polycotyleus (Paperna, 1973) collected on Labeobarbus marequensis (Smith, 1841), Enteromius trimaculatus (Peters, 1852) and Enteromius radiatus (Peters, 1853) was investigated from January to October 2008. Fish were collected at the Nwanedi-Luphephe dams, Limpopo River System, South Africa using gill, cast and seine nets and electrofishing gear. Enteromius radiatus and E. trimaculatus were the most infested compared with L. marequensis. Seasonal changes had an influence on the intensity of A. polycotyleus, with infestation rates higher in spring, summer and autumn. The adults predominantly infected the medial region of the second gill arch, whereas diporpae were mainly found on the first gill. Neither sex nor water quality changes had an influence on the intensity of the parasite. The health condition of the hosts was not affected by the parasite. The different infestation rates of the parasite between the species could be attributed to host characteristics, behaviour and habitat preferences. The selection of a particular gill/region could be attributed to space for attachment organs and food supply, as well as flow and velocity of the water over the gills. The occurrence of A. polycotyleus on E. radiatus constitutes a new host record.     

Genetic characterization of Hawaiian isolates of <Emphasis Type="Italic">Plasmodium relictum</Emphasis>reveals mixed-genotype infections

Background

The relatively recent introduction of a highly efficient mosquito vector and an avian pathogen (Plasmodium relictum) to an isolated island ecosystem with naïve, highly susceptible avian hosts provides a unique opportunity to investigate evolution of virulence in a natural system. Mixed infections can significantly contribute to the uncertainty in host-pathogen dynamics with direct impacts on virulence. Toward further understanding of how host-parasite and parasite-parasite relationships may impact virulence, this study characterizes within-host diversity of malaria parasite populations based on genetic analysis of the trap (thrombospondin-related anonymous protein) gene in isolates originating from Hawaii, Maui and Kauai Islands.

Methods

A total of 397 clones were produced by nested PCR amplification and cloning of a 1664 bp fragment of the trap gene from two malarial isolates, K1 (Kauai) and KV115 (Hawaii) that have been used for experimental studies, and from additional isolates from wild birds on Kauai, Maui and Hawaii Islands. Diversity of clones was evaluated initially by RFLP-based screening, followed by complete sequencing of 33 selected clones.

Results

RFLP analysis of trap revealed a minimum of 28 distinct RFLP haplotypes among the 397 clones from 18 birds. Multiple trap haplotypes were detected in every bird evaluated, with an average of 5.9 haplotypes per bird. Overall diversity did not differ between the experimental isolates, however, a greater number of unique haplotypes were detected in K1 than in KV115. We detected high levels of clonal diversity with clear delineation between isolates K1 and KV115 in a haplotype network. The patterns of within-host haplotype clustering are consistent with the possibility of a clonal genetic structure and rapid within-host mutation after infection.

Conclusion

Avian malaria (P. relictum) and Avipoxvirus are the significant infectious diseases currently affecting the native Hawaiian avifauna. This study shows that clonal diversity of Hawaiian isolates of P. relictum is much higher than previously recognized. Mixed infections can significantly contribute to the uncertainty in host-pathogen dynamics with direct implications for host demographics, disease management strategies, and evolution of virulence. The results of this study indicate a widespread presence of multiple-genotype malaria infections with high clonal diversity in native birds of Hawaii, which when coupled with concurrent infection with Avipoxvirus, may significantly influence evolution of virulence.

Reviewers

This article was reviewed by Joseph Schall (nominated by Laura Landweber), Daniel Jeffares (nominated by Anthony Poole) and Susan Perkins (nominated by Eugene Koonin).

     

Anti-carbamylated protein antibodies in the pre-symptomatic phase of rheumatoid arthritis,their relationship with multiple anti-citrulline peptide antibodies and association with radiological damage

IntroductionThe presence of a new autoantibody system, anti-carbamylated protein (anti-CarP) antibodies, has been identified in rheumatoid arthritis (RA). The presence of anti-CarP antibodies was evaluated in samples taken from individuals who subsequently developed RA before and after onset of symptoms and related to previously analysed antibodies against citrullinated peptides (ACPA specificities) and anti-CCP2.MethodsA total of 252 individuals, with 423 samples from before onset of symptoms of RA, and 197 population controls were identified as donors to the Medical Biobank of Northern Sweden; 192 of them were also sampled at the time of diagnosis. All samples were analysed for anti-CarP IgG and anti-CCP2 antibodies using ELISAs. Ten different antibody reactivities against citrullinated antigens (ACPA specificities) were analysed using a custom-made microarray based on the ImmunoCAP ISAC system (Phadia).ResultsThe concentration of anti-CarP antibodies was significantly increased in the pre-symptomatic individuals compared with controls (P <0.001) and also increased significantly after disease onset (P <0.001). The sensitivity for anti-CarP antibodies in the pre-symptomatic individuals was 13.9% (95% CI: 11 to 17.6) and 42.2% (95% CI: 35.4 to 49.3) following development of RA. Anti-CarP antibody positivity was found in 5.1% to 13.3% of individuals negative for anti-CCP2 or ACPA specificities. Presence of anti-CarP antibodies was significantly related to radiological destruction at baseline, at 24 months and also to radiological change (P <0.05, all).ConclusionsThe results indicate that anti-CarP antibodies are associated with disease development, even after adjusting for the presence of different ACPA fine specificities, and in anti-CCP2 negative individuals and contribute to the identification of a subset of patients with worse radiological progression of the disease independent of ACPA.

Electronic supplementary material

The online version of this article (doi:10.1186/s13075-015-0536-2) contains supplementary material, which is available to authorized users.     

Evaluation of miglustat as maintenance therapy after enzyme therapy in adults with stable type 1 Gaucher disease: a prospective,open-label non-inferiority study

Background

Previous studies have provided equivocal data on the use of miglustat as maintenance therapy in Gaucher disease type 1. We report findings from a clinical trial evaluating the effects of miglustat treatment in patients with stable type 1 Gaucher disease after enzyme therapy.

Methods

Adult type 1 Gaucher disease patients stabilized during at least 3 years of previous enzyme therapy were included in this 2-year, prospective, open-label non-inferiority study. The primary endpoint was percent change from baseline in liver volume. Secondary endpoints included changes in spleen volume, hemoglobin concentration and platelet count.

Results

Forty-two patients were enrolled (mean±SD age, 45.1±12.7 years; previous enzyme therapy duration 9.5±4.0 years). Median (range) exposure to miglustat 100 mg t.i.d. was 658 (3–765) days. Twenty-one patients discontinued treatment prematurely; 13 due to adverse events, principally gastrointestinal. The upper 95% confidence limit of mean percent change in liver volume from baseline to end of treatment was below the non-inferiority margin of 10% (–1.1%; 95%CI ?6.0, 3.9%). Mean (95%CI) changes in spleen volume, hemoglobin concentration and platelet count were 102 (24,180) mL, –0.95 (?1.38, –0.53) g/dL and ?44.1 (–57.6, –30.7) ×10⁹/L, respectively.

Conclusions

The primary efficacy endpoint was met; overall there was no change in liver volume during 24 months of miglustat therapy. Several patients showed a gradual deterioration in some disease manifestations, suggesting that miglustat could maintain clinical stability, but not in all patients. Miglustat demonstrated a predictable profile of safety and tolerability that was consistent with that reported in previous clinical trials and experience in clinical practice.

Trial registration

Clinicaltrials.gov identifier NCT00319046

     

EFFECTS OF MORINGA OLEIFERA SEED EXTRACT ON RUMEN FERMENTATION IN VITRO

Moringa oleifera is a pantropical tree of the family Moringaceae. A previously undescribed property of an aqueous extract from the seeds of this plant is the modulation of ruminal fermentation patterns, especially protein degradation, as demonstrated in a short-term batch incubation system. Gas, short chain fatty acids (SCFA) and cellulolytic enzyme activities were determined as general fermentation parameters. A dot blot assay able to directly detect true protein in rumen fluid samples was used to quantify protein degradation. For complex substrates the interpretation of protein degradation profiles was amended by polyacrylamide gel electrophoresis (PAGE) of the samples. When incubated with pure carbohydrates at a concentration of 1 mg ml^–1, the extract reduced microbial degradation of the model protein, bovine serum albumin (BSA), such that its concentration was at least 40% above the control after 12 h of incubation. Total protein degradation was thus delayed by approximately 9 h. When fermented along with wheat straw, leaf protein (Rubisco) was almost entirely protected during 12 h of fermentation. The degradation of soy proteins was retarded by at least 4- 6 h, depending on the protein band. There were strong side effects on the fermentation of pure cellulose (SCFA yield -60% after 12 h), whereas cellobiose and starch fermentation were less affected (-18 and -8%, respectively). When the complex substrates were fermented, SCFA yield was reduced by approximately 30% after 12 h. In our work we clearly demonstrate the efficacy of the new substance, which is neither a tannin nor a saponin, in an in vitro system, using pure as well as complex substrates. The properties shown in vitro for the crude extract suggest that it could have a positive effect on the protein metabolism of ruminants under intensive management and that negative side effects can be overcome by an optimized dosage. If the chemical nature of the active substance and its mechanism of action can be clarified, it may provide an alternative to replace critical synthetic feed additives (such as antibiotics) for high yielding dairy cows.