Learn More
The hemoglobinopathies, disorders of hemoglobin structure and production, protect against death from malaria. In sub-Saharan Africa, two such conditions occur at particularly high frequencies: presence of the structural variant hemoglobin S and alpha(+)-thalassemia, a condition characterized by reduced production of the normal alpha-globin component of(More)
We have recently proposed a new model for antigenic variation in Plasmodium falciparum that relies on a network of partially cross-protective immune responses to orchestrate this complex immune evasion process. In addition to exhibiting prolonged oscillations of single variants that resemble the sequential dominance of immunologically distinct antigenic(More)
The malaria parasite Plasmodium falciparum has evolved to prolong its duration of infection by antigenic variation of a major immune target on the surface of the infected red blood cell. This immune evasion strategy depends on the sequential, rather than simultaneous, appearance of immunologically distinct variants. Although the molecular mechanisms by(More)
Many pathogenic bacteria, fungi, and protozoa achieve chronic infection through an immune evasion strategy known as antigenic variation. In the human malaria parasite Plasmodium falciparum, this involves transcriptional switching among members of the var gene family, causing parasites with different antigenic and phenotypic characteristics to appear at(More)
Long-term epidemiological data reveal multi-annual fluctuations in the incidence of dengue fever and dengue haemorrhagic fever, as well as complex cyclical behaviour in the dynamics of the four serotypes of the dengue virus. It has previously been proposed that these patterns are due to the phenomenon of the so-called antibody-dependent enhancement (ADE)(More)
Neisseria meningitis is a human commensal bacterium that occasionally causes life-threatening disease. As with a number of other bacterial pathogens, meningococcal populations comprise distinct lineages, which persist over many decades and during global spread in the face of high rates of recombination. In addition, the propensity to cause invasive disease(More)
The prevalence of diverse MRSA (methicillin-resistant Staphylococcus aureus) types in both hospital and community settings is a major health problem worldwide. Here we compare hospital-acquired MRSAs with large type II SCCmec elements with those prevalent in both hospital and community settings with smaller type IV SCCmec elements. We find that the type II(More)
For many diseases (e.g., sexually transmitted infections, STIs), most individuals are aware of the potential risks of becoming infected, but choose not to take action ('respond') despite the information that aims to raise awareness and to increases the responsiveness or alertness of the population. We propose a simple mathematical model that accounts for(More)
In regions of high rates of malaria transmission, mosquitoes repeatedly transmit liver-tropic Plasmodium sporozoites to individuals who already have blood-stage parasitemia. This manifests itself in semi-immune children (who have been exposed since birth to Plasmodium infection and as such show low levels of peripheral parasitemia but can still be infected)(More)
Cathepsin D was purified by two-step affinity chromatography on concanavalin A-- and pepstatin--Sepharose. The main purification was achieved by washing the enzyme bound to the pepstatin--Sepharose column with buffered 6 M-urea. This step separated cathepsin D from all low- and high-molecular-weight impurities. Although the 1700-fold purified acid(More)