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DNA barcoding for disease vectors

DNA barcoding for disease vectors . Daniel Adjei Boakye Parasitology Department Noguchi Memorial Institute for Medical Research. elephantiasis. Lymphatic filariasis. Onchocerciasis. Health and Socio-economic impact. Leishmaniasis. Impact of parasitic diseases. Cause immense suffering

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DNA barcoding for disease vectors

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  1. DNA barcoding for disease vectors Daniel Adjei Boakye Parasitology Department Noguchi Memorial Institute for Medical Research Western and Central Africa DNA Barcoding meeting: Abuja, Nigeria

  2. elephantiasis Lymphatic filariasis Western and Central Africa DNA Barcoding meeting: Abuja, Nigeria

  3. Onchocerciasis • Health and Socio-economic impact Western and Central Africa DNA Barcoding meeting: Abuja, Nigeria

  4. Leishmaniasis Western and Central Africa DNA Barcoding meeting: Abuja, Nigeria

  5. Impact of parasitic diseases • Cause immense suffering • Life-long disabilities • Impair childhood growth and development • Promote poverty, impair education and • Economic development • Arable land deserted • Population affected • Mortality Western and Central Africa DNA Barcoding meeting: Abuja, Nigeria

  6. Neglected Tropical Diseases and Malaria Western and Central Africa DNA Barcoding meeting: Abuja, Nigeria

  7. Vectors of Neglected Tropical Diseases Western and Central Africa DNA Barcoding meeting: Abuja, Nigeria

  8. Importance of correct identification • Understanding the diversity of vector species and their respective vectorial importance is necessary for any targeted control effort • Studies on Vector species • Identification and clarification of species status • Biology and ecology of vectors • Vectorial importance of different species Western and Central Africa DNA Barcoding meeting: Abuja, Nigeria

  9. Members of the S. damnosum complex in West Africa • Determination of important vector species • Basis for mapping limits of control programme • Only larvae can be identified with precision Western and Central Africa DNA Barcoding meeting: Abuja, Nigeria

  10. Anopheles gambiae species complex Anopheles gambiae sensu lato An. gambaie s.s An. quadrannulatus An. arabiensis An. bwambae An. melas An. merus Western and Central Africa DNA Barcoding meeting: Abuja, Nigeria

  11. Taxonomic challenges within An. gambiae s.s • Genetic discontinuities • from chromosomal analysis (Coluzzi et al 1985) • Five chromosomal forms in West Africa: Mopti; Bamako; Bissau; Forest; Savanna • in the ribosomal DNA region (rDNA) (Favia et al 1997) • Two molecular forms described (della Torre et al 2001; 2005) Western and Central Africa DNA Barcoding meeting: Abuja, Nigeria

  12. Problems associated with current identification • In Mali and Burkina Faso, the M and S forms correspond to the Mopti and Savanna chromosomal forms • Molecular forms do not always correspond to the chromosomal forms in other countries • The two molecular forms may be a reflection of the presence of two different species in what is considered as one species – An. gambiae s.s. Western and Central Africa DNA Barcoding meeting: Abuja, Nigeria

  13. Practical consequences for disease control • Susceptibility to insecticides • Differences in disease transmission capabilities • Adaptation to different breeding sites • There is therefore the need to understand whether there are 2 or only 1 species Western and Central Africa DNA Barcoding meeting: Abuja, Nigeria

  14. Methodology Intergenic spacer of the rDNA region of the X-chromosome Scott et al. (1993), Favia et al. (1997) and Fanello et al (2002) Morphological identification - Gillies and Coetzee (1987) Multiplex PCR for species identification PCR – RFLP for molecular form identification Western and Central Africa DNA Barcoding meeting: Abuja, Nigeria

  15. Methodology Sequence alignment & comparisons: The sequences obtained were aligned using BioEdit (Hall, 1999) BLAST database search for closely related sequences in the Genebank database . Analysis for species relationships (Kimura 2-parameter (K2P) model; Kimura, 1980: Neighbour-Joining (NJ) tree; Saitou & Nei, 1987) were conducted in Mega 4 (Tamura et al., 2007). PCR of CO1 fragment & Sequencing: (Applied Biosystems 377 automated DNA sequencer) Western and Central Africa DNA Barcoding meeting: Abuja, Nigeria

  16. Preliminary results Western and Central Africa DNA Barcoding meeting: Abuja, Nigeria

  17. Preliminary results • Molecular forms of An. gambiae s.s. Western and Central Africa DNA Barcoding meeting: Abuja, Nigeria

  18. Example of phylogenetic tree Western and Central Africa DNA Barcoding meeting: Abuja, Nigeria

  19. Ghana Mosquitoes’ file in the Completed Project section of the Barcode of Life website (http://www.barcodinglife.org). Western and Central Africa DNA Barcoding meeting: Abuja, Nigeria

  20. Conclusion • DNA barcode can be used to • Separate out closely related members of sibling species in vectors of diseases • Draw relationships between species collected from wider geographical areas • Determine the presence of individuals currently unidentified using the available techniques Western and Central Africa DNA Barcoding meeting: Abuja, Nigeria

  21. Acknowledgements • Funding: • JRS Biodiversity Foundation • World Health Organization • Gate’s Foundation • Collaborators at the NMIMR • Prof. Michael Wilson • Dr Maxwell Appawu • Dziedzom de Souza • Hilaria Amuzu • Ignatius Ndong Western and Central Africa DNA Barcoding meeting: Abuja, Nigeria

  22. Thank you Western and Central Africa DNA Barcoding meeting: Abuja, Nigeria

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