AIMS OF THE PROJECT
The Wellcome Trust has funded The Pathogen Genomics group in collaboration with Dr. Paul Bates, Dr. Rod Dillon and Professor Mike Lehane of the Liverpool School of Tropical Medicine to undertake a gene discovery project on Lutzomyia longipalpis. The data obtained from these studies will direct the construction and use of microarrays for this organism.This project has two main aims. The first is to generate cDNA microarrays from Lutzomyia longipalpis that can be used to investigate the transcriptomics of phlebotomine sandflies. The second aim is to use these microarrays to test the hypothesis that sand flies respond to Leishmania infection by upregulating/downregulating expression of specific genes. Analysis of such responses is an essential component of understanding the interaction between the Leishmania parasite and its sand fly vector.
Background
The leishmaniases are vector-borne diseases exclusively transmitted by phlebotomine sand flies of the genera Phlebotomus and Lutzomyia. In South America Lu. longipalpis is the main vector of visceral leishmaniasis (the most serious form of the disease), in both sylvatic and peridomestic environments. Colonisation of urban areas by Lu. longipalpis is believed to be an important factor in the recent increase of visceral leishmaniasis in South America. Even in sub-tropical regions where these diseases have not traditionally been as important, their sub-clinical status has been elevated to clinical disease by association with HIV infection. Many species of phlebotomine sand fly are inherently refractory to the full development of Leishmania. Thus of the 700 or so species described to date, only 10% have been incriminated as vectors. Further, most vector competent species are natural hosts to only one Leishmania species. This specificity is due to a number of factors including the ability of the parasite to develop within the particular vector. Certain vectors will only support those parasites that they naturally transmit, for example P. papatasi/L. major and P.sergenti/L. tropica. Other vectors are more permissive, for example Lu. longipalpis, that can be experimentally infected with a variety of Leishmania species such as L. mexicana and L. major, in addition to the only parasite that it transmits under natural conditions L. infantum syn. chagasi.The PSU has already generated annotated genome sequence data for:
Library construction
Messenger RNA was isolated from female sandflies with a range of physiological and infection histories to generate as diverse a collection of cDNA clones as possible. The colony of Lutzomyia longipalpis (Jacobina strain, Bahia, Brazil) kept at the Liverpool School of Tropical Medicine was used. mRNA was prepared from a total of 1,950 sandflies.- Uninfected control flies fed on blood or sugar meals (900 flies)
- Infected flies (125) fed with a rabbit blood meal containing Leishmania infantum (chagasi) amastigotes (2x106 ml-1)
- Infected flies (375) fed with a rabbit blood meal containing L. mexicana amastigotes (2x106 ml-1).
Insects in each of the above groups were harvested daily from day 1-7 after the meal. - Sandflies (450) fed with the bacterium Pantoea agglomerans isolated from an insect and an insect pathogen Serratia marcescens
- Sandflies (100) injected with S. marcescens.
A normalised cDNA library has been made by the Soares lab in Iowa.
Sequences have been obtained from both ends of 15,000 clones.Accessing the L. longipalpis sequence data
Individual sequence reads, as well as phrap assembled contigs, can be downloaded from the FTP site.
Searching the Lutzomyia EST sequence data online
You can also search against Lutzomyia cDNAs using our online BLAST server.
Enquiries
