Alpha thalassemia among sickle cell anaemia patients in Kampala, Uganda

Background: Sickle cell anaemia is prevalent in sub Saharan Africa. While \u3b1+-thalassaemia is known to modulate sickle cell anaemia, its magnitude and significance in Uganda have hitherto not been described. Objectives: To determine the prevalence of \u3b1+thalassaemia among sickle cell anaemia patients in Mulago Hospital and to describe the clinical and laboratory findings in these patients. Methods: A cross sectional study was carried out on patients with sickle cell anaemia in Kampala. Dried blood spots were used to analyze for the deletional \u3b1+ thalassaemia using multiplex polymerase chain reaction. Results: Of the 142 patients with sickle cell anaemia, 110 (77.5%) had the \u3b1+thalassaemia deletion. The gene frequency of (-\u3b1) was 0.425. Ninety one percent (100/110) of those with \u3b1+thalassaemia were heterozygous (\u3b1/\u3b1-). Amongst the patients older than 60 months, 15 (83.3%) of those without \u3b1+thalassaemia had significant hepatomegaly of greater than 4 cm compared to 36 (45.6%) of those with \u3b1+thalassaemia (p=0.003). Conclusion: The gene frequency of (-\u3b1) of 0.425 noted in this study is higher than that reported from many places in Africa. Concurrent alpha thalassemia might be a protective trait against significant hepatomegaly in sickle cell anaemia patients more than 60 months of age at Mulago hospital. Keywords: Alpha thalassemia; sickle cell anaemia patient; Kampala; Ugand

Genomic and transcriptomic comparisons of closely related malaria parasites differing in virulence and sequestration pattern [version 1; referees: 2 approved]

Background: Malaria parasite species differ greatly in the harm they do to humans. While P. falciparum kills hundreds of thousands per year, P. vivax kills much less often and P. malariae is relatively benign. Strains of the rodent malaria parasite Plasmodium chabaudi show phenotypic variation in virulence during infections of laboratory mice. This make it an excellent species to study genes which may be responsible for this trait. By understanding the mechanisms which underlie differences in virulence we can learn how parasites adapt to their hosts and how we might prevent disease. Methods: Here we present a complete reference genome sequence for a more virulent P. chabaudi strain, PcCB, and perform a detailed comparison with the genome of the less virulent PcAS strain. Results: We found the greatest variation in the subtelomeric regions, in particular amongst the sequences of the pir gene family, which has been associated with virulence and establishment of chronic infection. However, despite substantial variation at the sequence level, the repertoire of these genes has been largely maintained, highlighting the requirement for functional conservation as well as diversification in host-parasite interactions. However, a subset of pir genes, previously associated with increased virulence, were more highly expressed in PcCB, suggesting a role for this gene family in virulence differences between strains. We found that core genes involved in red blood cell invasion have been under positive selection and that the more virulent strain has a greater preference for reticulocytes, which has elsewhere been associated with increased virulence. Conclusions: These results provide the basis for a mechanistic understanding of the phenotypic differences between Plasmodium chabaudi strains, which might ultimately be translated into a better understanding of malaria parasites affecting humans

Identification of gametocyte-associated pir genes in the rodent malaria parasite, Plasmodium chabaudi chabaudi AS

Acknowledgements: We thank the Biological Research Facility and Flow Cytometry Science Technology Platform at the Francis Crick Institute for their support and assistance. We thank Prisca Hill and Sarah Manni for their technical support in in-vivo experiments. We thank Ana Antonello for the gel shown in Additional File 2 Figure 1B.Funder: The Francis Crick InstituteObjective: To analyse the transcriptional profiles of the pir multigene family of Plasmodium chabaudi chabaudi in male and female gametocytes isolated from the blood of infected mice. Results: Infected red blood cells containing female and male P. chabaudi gametocytes transcribe a distinct set of genes encoded by the multigene family pir. The overall patterns are similar to what has been observed in the close relative P. berghei, but here we show that gametocyte-associated pir genes are distinct from those involved in chronic blood-stage infection and highlight a male-associated pir gene which should be the focus of future studies

Identification of gametocyte-associated pir genes in the rodent malaria parasite, Plasmodium chabaudi chabaudi AS

Abstract Objective To analyse the transcriptional profiles of the pir multigene family of Plasmodium chabaudi chabaudi in male and female gametocytes isolated from the blood of infected mice. Results Infected red blood cells containing female and male P. chabaudi gametocytes transcribe a distinct set of genes encoded by the multigene family pir. The overall patterns are similar to what has been observed in the close relative P. berghei, but here we show that gametocyte-associated pir genes are distinct from those involved in chronic blood-stage infection and highlight a male-associated pir gene which should be the focus of future studies

Identification of gametocyte-associated pir genes in the rodent malaria parasite, Plasmodium chabaudi chabaudi AS.

OBJECTIVE: To analyse the transcriptional profiles of the pir multigene family of Plasmodium chabaudi chabaudi in male and female gametocytes isolated from the blood of infected mice. RESULTS: Infected red blood cells containing female and male P. chabaudi gametocytes transcribe a distinct set of genes encoded by the multigene family pir. The overall patterns are similar to what has been observed in the close relative P. berghei, but here we show that gametocyte-associated pir genes are distinct from those involved in chronic blood-stage infection and highlight a male-associated pir gene which should be the focus of future studies

ICAM-1 is a key receptor mediating cytoadherence and pathology in the Plasmodium chabaudi malaria model

Abstract Background Parasite cytoadherence within the microvasculature of tissues and organs of infected individuals is implicated in the pathogenesis of several malaria syndromes. Multiple host receptors may mediate sequestration. The identity of the host receptor(s), or the parasite ligand(s) responsible for sequestration of Plasmodium species other than Plasmodium falciparum is largely unknown. The rodent malaria parasites may be useful to model interactions of parasite species, which lack the var genes with their respective hosts, as other multigene families are shared between the species. The role of the endothelial receptors ICAM-1 and CD36 in cytoadherence and in the development of pathology was investigated in a Plasmodium chabaudi infection in C57BL/6 mice lacking these receptors. The schizont membrane-associated cytoadherence (SMAC) protein of Plasmodium berghei has been shown to exhibit reduced CD36-associated cytoadherence in P. berghei ANKA-infected mice. Methods Parasite tissue sequestration and the development of acute stage pathology in P. chabaudi infections of mice lacking CD36 or ICAM-1, their respective wild type controls, and in infections with mutant P. chabaudi parasites lacking the smac gene were compared. Peripheral blood parasitaemia, red blood cell numbers and weight change were monitored throughout the courses of infection. Imaging of bioluminescent parasites in isolated tissues (spleen, lungs, liver, kidney and gut) was used to measure tissue parasite load. Results This study shows that neither the lack of CD36 nor the deletion of the smac gene from P. chabaudi significantly impacted on acute-stage pathology or parasite sequestration. By contrast, in the absence of ICAM-1, infected animals experience less anaemia and weight loss, reduced parasite accumulation in both spleen and liver and higher peripheral blood parasitaemia during acute stage malaria. The reduction in parasite tissue sequestration in infections of ICAM-1 null mice is maintained after mosquito transmission. Conclusions These results indicate that ICAM-1-mediated cytoadherence is important in the P. chabaudi model of malaria and suggest that for rodent malarias, as for P. falciparum, there may be multiple host and parasite molecules involved in sequestration

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Additional file 4. Similar levels of Δsmac and wild-type parasites accumulated in kidney and gut at days 4, 7 and 9 post-infection (n = 6)

MOESM2 of ICAM-1 is a key receptor mediating cytoadherence and pathology in the Plasmodium chabaudi malaria model

Additional file 2. PCR primers for verification of integration