Conference Agenda

The alkyne modified thymidine analogue 5-ethynyl-2′-deoxyuridine (EdU) is a gold standard chemical probe for DNA synthesis and proliferation detection in mammalian cells. EdU is incorporated into nuclear DNA via the thymidine salvage pathway and can be detected using copper catalysed azide-alkyne cycloaddition (CuAAC) with a fluorescent azide. However, as Plasmodium malaria parasites lack the thymidine kinase enzyme that is essential for metabolism, EdU and similar probes (e.g., BrdU) cannot be utilised. While P. falciparum engineered to express thymidine kinase from Herpes simplex virus can overcome this limitation and enable DNA labelling studies using BrdU and EdU, this approach may not be feasible for analysis different Plasmodium species, multiple laboratory lines and field isolates. We have designed and synthesised new thymidine-based probes that overcome the need for an endogenous thymidine kinase enzyme. We have shown that these DNADetect™ probes robustly label replicating asexual intraerythrocytic P. falciparum parasites using CuAAC with a fluorescent azide and flow cytometry. The DNADetect™ chemical probes are synthetically accessible and thus have broad applicability as tools to further understand the biology of different Plasmodium species, including laboratory lines and clinical isolates.

Simulium blackflies of the damnosum species complex, known vectors of the parasitic nematode causing human onchocerciasis (river blindness), can travel long distances of 20 to 600 km with wind assistance. Onchocerciasis is marked by severe skin lesions, blindness, and epilepsy, mainly affects remote rural areas in sub-Saharan Africa, Yemen, Brazil, and Venezuela. In Ghana, extensive small-scale mining has polluted fast-flowing rivers, the natural breeding habitats for these blackflies, prompting their migrate in search of suitable environments and raising concerns about the spread of onchocerciasis to previously unaffected areas. In June 2023, blackflies were reported in Accra, a city previously free of onchocerciasis. This prompted an investigation, where 270 female blackflies were collected from 14 communities in Ghana using human landing catches. Whole genome sequencing and principal components analysis of 138,128 SNPs, along with k-means clustering, indicated that blackflies in Accra were genetically closer to those in the Eastern region of Ghana than to those from other parts of the country. This suggests a southeastern origin. These findings highlight the need for further research into the migration pathways of these blackflies and the implications of their urban presence for the spread of onchocerciasis.

The major intermediate host for the medically significant blood fluke Schistosoma haematobium, which is endemic primarily in African, is the freshwater snail Bulinus globosus. The taxonomic status of the species that comprise the B. globosus group is still remains controversial. We examined genetic variation of B. globosus using analyses of the intron 3 region of the arginine kinase gene (AkInt3). A total 81 B. globosus snails were collected from three different localities in Kenya. The 81 B. globosus snails were classified into 44 haplotypes (H1 – H44). These haplotypes were separated into three haplogroups (I – III). In addition, heterozygosity in the AkInt3 sequence was also detected. DNA recombination haplotypes between different haplogroups were commonly found in the heterozygous samples. High levels of genetic variability and heterozygosity were shown by AkInt3 sequence analysis, supporting the potential as a genetic marker to shed light on B. globosus population genetics. Additionally, our research shows that the B. globosus populations in Kenya formed a “species complex”.