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Anopheles gambiae genome
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News & Comment
Anopheles gambiae genome A project to sequence the 260 million base pairs of Anopheles gambiae, the most important insect vector of the malaria parasite in sub-Saharan Africa, was recently agreed by an international network of researchers at a meeting at the Institut Pasteur, France. The first version of the genome, which will be freely available on public databases, should be ready by the end of 2001 and should cost less than US$10 million. The initial work, to be carried out by Celera Genomics and Genoscope (the French National Sequencing Centre), will use the ‘Whole Genome Shotgun’ technique. Sequence closure and finishing will be performed by Genoscope, the Institute for Genomic Research, the European Bioinformatics Institute and other groups from France, Greece, Germany, UK and the USA. The French Government will provide funds for part of the project, and other sources of finance, including the European Union and USA agencies, are being approached. It is hoped that this collaboration will eventually cover other Anopheles spp. JT
Making a difference Evidence from molecular studies is causing scientists to rethink the taxonomy of the piroplasm Babesia. Classically, biologists have relied on the morphology of the trophozoite inside erythrocytes to distinguish between small and large Babesia; in addition, the absence of a lymphocytic stage in the life cycle of the parasite has been used to
TRENDS in Parasitology Vol.17 No.6 June 2001
distinguish Babesia spp. from the related piroplasm Theileria, which exhibits this stage. It was recently shown that the size of B. gibsoni (a parasite that infects dogs and is prevalent in Asia) depends upon the host species [Fukumoto, S. et al. (2000) J. Parasitol. 86, 956–959]. Babesia gibsoni infection was induced in immunodeficient SCID-mice that had received canine erythrocytes. The parasite was significantly larger in the mouse host (3.5 µm average diameter) than that in the natural canine host (1.7 µm average diameter). Using molecular techniques, based on small-subunit rDNA analysis, researchers showed that the large Babesia did not separate from the small Babesia, suggesting that they are not distinct taxonomic groups [Homer, M.J. et al. (2000) Clin. Microbiol. Rev. 13, 451–469]. In addition, it was found that some Babesia spp. grouped with Theileria spp. (e.g. Babesia equi, which was subsequently renamed Theileria equi). TS
Paying the toll to Metchnikoff The founder of modern immunology, the embryologist Elie Metchnikoff, an enthusiastic supporter of Darwinism, proposed that evolutionary pressure imposed by microbiological challenge can cause genetic selection. A recent review on the recognition of pathogens supports this view [Fallon, P.G. et al. (2000) Trends Immunol. 22, 63–66]. Early invertebrates sense pathogens through pathogen-associated molecular patterns (PAMPs). The invertebrate PAMP receptor belongs to the Toll-receptor family. A sub-class
of Toll receptors, which has been extensively studied in Drosophila, has an intracellular cassette with similarity to the interleukin-1 (IL-1) receptor [Toll–IL-1 receptor homologous region (TIR)]. Searching parasite sequence databases revealed a putative TIR domain in the parasitic nematode Strongyloides stercoralis. The authors suggest that this receptor might play a crucial role in the control of Wolbachia infections of the nematode. Furthermore, TIR cassettes are present in several plant genes, suggesting that the TIR module first arose before the animal–plant divide. TS
Protection induced by MSP-1 vaccines High antibody titres against merozoite surface protein (MSP)-1 can protect against Plasmodium falciparum infection. A recent vaccine trial tested two vaccines on Aotus monkeys [Stowers, S.W. et al. (2001) Infect. Immun. 69, 1536–1546]. The first vaccine, which protected 86% of monkeys from uncontrolled parasitaemia, was based on the 42-kDa C-terminal portion of MSP-1 and was expressed as a secreted protein in baculovirus-infected insect cells. The second vaccine, based on the smaller, 19-kDa C-terminal portion of MSP-1, was expressed by the yeast Saccharomyces cerevisiae and protected only 43% of monkeys from uncontrolled parasitaemia. In each case, protection was only seen when high antibody levels were obtained by formulation of the vaccine in Freund’s adjuvant, and not with an alternative adjuvant (MF59). SHK
Preliminary release of genetically modified moths Cotton growers in Arizona have given a US$1 million grant to the US Department of Agriculture and the University of California at Riverside to fund research into the control of the cotton pest, the pink bollworm larva of the moth Pectinophora gossypiella. The larvae are estimated to cost the US cotton industry US$200 million annually through crop damage and control costs. To track any cross-species genetic transfer, adult males carrying a marker gene for a green fluorescent protein from a jellyfish will be released. Ultimately, it is expected that moths carrying a dominant, repressible, lethal gene will be released. The effects of such genes are suppressed in the insects as they develop in the laboratory, but will kill the offspring of
those they mate with in the field. In contrast to the use of insecticides, this method of control should not have any serious effects
on local ecology because the destruction of the moths, which are not native to the USA, will be highly specific. JT
http://parasites.trends.com 1471-4922/01/$ – see front matter © 2001 Elsevier Science Ltd. All rights reserved.
News & Comment
Anopheles gambiae genome A project to sequence the 260 million base pairs of Anopheles gambiae, the most important insect vector of the malaria parasite in sub-Saharan Africa, was recently agreed by an international network of researchers at a meeting at the Institut Pasteur, France. The first version of the genome, which will be freely available on public databases, should be ready by the end of 2001 and should cost less than US$10 million. The initial work, to be carried out by Celera Genomics and Genoscope (the French National Sequencing Centre), will use the ‘Whole Genome Shotgun’ technique. Sequence closure and finishing will be performed by Genoscope, the Institute for Genomic Research, the European Bioinformatics Institute and other groups from France, Greece, Germany, UK and the USA. The French Government will provide funds for part of the project, and other sources of finance, including the European Union and USA agencies, are being approached. It is hoped that this collaboration will eventually cover other Anopheles spp. JT
Making a difference Evidence from molecular studies is causing scientists to rethink the taxonomy of the piroplasm Babesia. Classically, biologists have relied on the morphology of the trophozoite inside erythrocytes to distinguish between small and large Babesia; in addition, the absence of a lymphocytic stage in the life cycle of the parasite has been used to
TRENDS in Parasitology Vol.17 No.6 June 2001
distinguish Babesia spp. from the related piroplasm Theileria, which exhibits this stage. It was recently shown that the size of B. gibsoni (a parasite that infects dogs and is prevalent in Asia) depends upon the host species [Fukumoto, S. et al. (2000) J. Parasitol. 86, 956–959]. Babesia gibsoni infection was induced in immunodeficient SCID-mice that had received canine erythrocytes. The parasite was significantly larger in the mouse host (3.5 µm average diameter) than that in the natural canine host (1.7 µm average diameter). Using molecular techniques, based on small-subunit rDNA analysis, researchers showed that the large Babesia did not separate from the small Babesia, suggesting that they are not distinct taxonomic groups [Homer, M.J. et al. (2000) Clin. Microbiol. Rev. 13, 451–469]. In addition, it was found that some Babesia spp. grouped with Theileria spp. (e.g. Babesia equi, which was subsequently renamed Theileria equi). TS
Paying the toll to Metchnikoff The founder of modern immunology, the embryologist Elie Metchnikoff, an enthusiastic supporter of Darwinism, proposed that evolutionary pressure imposed by microbiological challenge can cause genetic selection. A recent review on the recognition of pathogens supports this view [Fallon, P.G. et al. (2000) Trends Immunol. 22, 63–66]. Early invertebrates sense pathogens through pathogen-associated molecular patterns (PAMPs). The invertebrate PAMP receptor belongs to the Toll-receptor family. A sub-class
of Toll receptors, which has been extensively studied in Drosophila, has an intracellular cassette with similarity to the interleukin-1 (IL-1) receptor [Toll–IL-1 receptor homologous region (TIR)]. Searching parasite sequence databases revealed a putative TIR domain in the parasitic nematode Strongyloides stercoralis. The authors suggest that this receptor might play a crucial role in the control of Wolbachia infections of the nematode. Furthermore, TIR cassettes are present in several plant genes, suggesting that the TIR module first arose before the animal–plant divide. TS
Protection induced by MSP-1 vaccines High antibody titres against merozoite surface protein (MSP)-1 can protect against Plasmodium falciparum infection. A recent vaccine trial tested two vaccines on Aotus monkeys [Stowers, S.W. et al. (2001) Infect. Immun. 69, 1536–1546]. The first vaccine, which protected 86% of monkeys from uncontrolled parasitaemia, was based on the 42-kDa C-terminal portion of MSP-1 and was expressed as a secreted protein in baculovirus-infected insect cells. The second vaccine, based on the smaller, 19-kDa C-terminal portion of MSP-1, was expressed by the yeast Saccharomyces cerevisiae and protected only 43% of monkeys from uncontrolled parasitaemia. In each case, protection was only seen when high antibody levels were obtained by formulation of the vaccine in Freund’s adjuvant, and not with an alternative adjuvant (MF59). SHK
Preliminary release of genetically modified moths Cotton growers in Arizona have given a US$1 million grant to the US Department of Agriculture and the University of California at Riverside to fund research into the control of the cotton pest, the pink bollworm larva of the moth Pectinophora gossypiella. The larvae are estimated to cost the US cotton industry US$200 million annually through crop damage and control costs. To track any cross-species genetic transfer, adult males carrying a marker gene for a green fluorescent protein from a jellyfish will be released. Ultimately, it is expected that moths carrying a dominant, repressible, lethal gene will be released. The effects of such genes are suppressed in the insects as they develop in the laboratory, but will kill the offspring of
those they mate with in the field. In contrast to the use of insecticides, this method of control should not have any serious effects
on local ecology because the destruction of the moths, which are not native to the USA, will be highly specific. JT
http://parasites.trends.com 1471-4922/01/$ – see front matter © 2001 Elsevier Science Ltd. All rights reserved.