Category: Genomics of Apicomplexa

Genetic diversity of Cryptosporidium isolates from patients in North India.

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Genetic diversity of Cryptosporidium isolates from patients in North India.
Int J Infect Dis. 2013 Aug;17(8):e601-5
Authors: Sharma P, Sharma A, Sehgal R, Malla N, Khurana S
Abstract
BACKGROU…

Low level of sequence diversity at merozoite surface protein-1 locus of Plasmodium ovale curtisi and P. ovale wallikeri from Thai isolates.

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Low level of sequence diversity at merozoite surface protein-1 locus of Plasmodium ovale curtisi and P. ovale wallikeri from Thai isolates.

PLoS One. 2013;8(3):e58962

Authors: Putaporntip C, Hughes AL, Jongwutiwes S

Abstract
BACKGROUND: The merozoite surface protein-1 (MSP-1) is a candidate target for the development of blood stage vaccines against malaria. Polymorphism in MSP-1 can be useful as a genetic marker for strain differentiation in malarial parasites. Although sequence diversity in the MSP-1 locus has been extensively analyzed in field isolates of Plasmodium falciparum and P. vivax, the extent of variation in its homologues in P. ovale curtisi and P. ovale wallikeri, remains unknown.
METHODOLOGY/PRINCIPAL FINDINGS: Analysis of the mitochondrial cytochrome b sequences of 10 P. ovale isolates from symptomatic malaria patients from diverse endemic areas of Thailand revealed co-existence of P. ovale curtisi (n = 5) and P. ovale wallikeri (n = 5). Direct sequencing of the PCR-amplified products encompassing the entire coding region of MSP-1 of P. ovale curtisi (PocMSP-1) and P. ovale wallikeri (PowMSP-1) has identified 3 imperfect repeated segments in the former and one in the latter. Most amino acid differences between these proteins were located in the interspecies variable domains of malarial MSP-1. Synonymous nucleotide diversity (πS) exceeded nonsynonymous nucleotide diversity (πN) for both PocMSP-1 and PowMSP-1, albeit at a non-significant level. However, when MSP-1 of both these species was considered together, πS was significantly greater than πN (p<0.0001), suggesting that purifying selection has shaped diversity at this locus prior to speciation. Phylogenetic analysis based on conserved domains has placed PocMSP-1 and PowMSP-1 in a distinct bifurcating branch that probably diverged from each other around 4.5 million years ago.
CONCLUSION/SIGNIFICANCE: The MSP-1 sequences support that P. ovale curtisi and P. ovale wallikeri are distinct species. Both species are sympatric in Thailand. The low level of sequence diversity in PocMSP-1 and PowMSP-1 among Thai isolates could stem from persistent low prevalence of these species, limiting the chance of outcrossing at this locus.

PMID: 23536840 [PubMed – indexed for MEDLINE]

Whole-genome sequencing of Theileria parva strains provides insight into parasite migration and diversification in the African continent.

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Whole-genome sequencing of Theileria parva strains provides insight into parasite migration and diversification in the African continent.
DNA Res. 2013 Jun;20(3):209-20
Authors: Hayashida K, Abe T, Weir W, N…

Diversity of Babesia in Ixodes ricinus ticks in Poland.

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Diversity of Babesia in Ixodes ricinus ticks in Poland.

Adv Med Sci. 2012;57(2):364-9

Authors: Welc-Falęciak R, Bajer A, Paziewska-Harris A, Baumann-Popczyk A, Siński E

Abstract
PURPOSE: The aims of this study were: (1) to estimate Babesia prevalence in the most common species of tick in Poland, Ixodes ricinus, in two recreational areas (Urwitałt in the Mazury Lake District and Bielański Forest in Warsaw), and (2) to evaluate the molecular diversity of Babesia isolates in questing I. ricinus in Poland.
MATERIAL AND METHODS: Questing ticks were collected from vegetation in forest areas in Urwitałt near Mikołajki and in Bielański Forest (Warsaw). Purified genomic DNA was used with specific primers to amplify a fragment of the Babesia spp. 18S rRNA gene.
RESULTS: Tick-drag indices for I. ricinus were high in both study areas, reaching somewhat higher values in Urwitałt than in Bielański Forest. The overall prevalence of Babesia spp. in examined ticks was 1.6%. In Urwitałt, two strains of B. microti were identified using rRNA sequences: the enzootic Munich strain and an isolate close to the zoonotic Jena strain. The proportion of infections due to these two strains in questing ticks reversed over a six-year period. During 3 years of study in Bielański Forest, all Babesia isolates obtained from I. ricinus were identical to Babesia sp. EU1 (B. venatorum), previously recognized as an agent of human babesiosis.
CONCLUSIONS: This study has confirmed the presence of enzoonotic and zoonotic Babesia species/strains in the abundant human-biting tick I. ricinus in recreational areas in Poland. It has also shown that the distribution of different genotypes has changed over time, however the reasons for these fluctuations still remain to be investigated.

PMID: 22968337 [PubMed – indexed for MEDLINE]

Cryptosporidium scrofarum n. sp. (Apicomplexa: Cryptosporidiidae) in domestic pigs (Sus scrofa).

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Cryptosporidium scrofarum n. sp. (Apicomplexa: Cryptosporidiidae) in domestic pigs (Sus scrofa).

Vet Parasitol. 2013 Jan 31;191(3-4):218-27

Authors: Kváč M, Kestřánová M, Pinková M, Květoňová D, Kalinová J, Wagnerová P, Kotková M, Vítovec J, Ditrich O, McEvoy J, Stenger B, Sak B

Abstract
We describe the morphological, biological, and molecular characteristics of Cryptosporidium pig genotype II and propose the species name Cryptosporidium scrofarum n. sp. to reflect its prevalence in adult pigs worldwide. Oocysts of C. scrofarum are morphologically indistinguishable from C. parvum, measuring 4.81-5.96 μm (mean=5.16)×4.23-5.29 μm (mean=4.83) with a length to width ratio of 1.07±0.06 (n=400). Oocysts of C. scrofarum obtained from a naturally infected pig were infectious for 8-week-old pigs but not 4-week-old pigs. The prepatent period in 8-week-old Cryptosporidium-naive pigs was 4-6 days and the patent period was longer than 30 days. The infection intensity of C. scrofarum in pigs was generally low, in the range 250-4000 oocysts per gram of feces. Infected pigs showed no clinical signs of cryptosporidiosis and no pathology was detected. Cryptosporidium scrofarum was not infectious for adult SCID mice, adult BALB/c mice, Mongolian gerbils (Meriones unguiculatus), southern multimammate mice (Mastomys coucha), yellow-necked mice (Apodemus flavicollis), or guinea pigs (Cavia porcellus). Phylogenetic analyses based on small subunit rRNA, actin, and heat shock protein 70 gene sequences revealed that C. scrofarum is genetically distinct from all known Cryptosporidium species.

PMID: 23021264 [PubMed – indexed for MEDLINE]

Eimeria that infect fish are diverse and are related to, but distinct from, those that infect terrestrial vertebrates.

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Eimeria that infect fish are diverse and are related to, but distinct from, those that infect terrestrial vertebrates.

Infect Genet Evol. 2012 Dec;12(8):1810-5

Authors: Molnár K, Ostoros G, Dunams-Morel D, Rosenthal BM

Abstract
The Eimeria are ubiquitous parasites (Phylum: Apicomplexa; family: Coccidia) of the gut epithelium of vertebrates which complete their development in a single host species and whose sporocysts may be recognized by the presence of a Stieda body through which their sporozoites excyst. Their diversity and relationship to other kinds of coccidia have been successfully explored by molecular systematic studies based on the sequencing the 18S ribosomal DNA. To date, most attention has been paid to the diversity and evolutionary relationships of Eimeria spp. parasitizing terrestrial vertebrates, most especially those species infecting domesticated birds and mammals. Regrettably, no Eimeria have yet been considered from the Earth’s first vertebrates: the fish. If Eimeria first evolved in fish, then extant piscine parasites should comprise a deeply branching assemblage at the base of well-constructed phylogenetic trees. Here, we sequenced portions of ribosomal DNA from several such isolates (from Eimeria anguillae, Eimeria daviesae, Eimeria percae, Eimeria variabilis, Eimeria rutili and Eimeria nemethi) and compared them to one another as well as to other available sequences from the parasites of fish and terrestrial vertebrates, in order to better understand their diversity and origins. By establishing that such piscine parasites comprise a deeply branching clade at the base of the Eimeriidae, these data substantiate the hypothesis that Eimeria may have originated in fish. Plainly, a great deal of coccidian diversity awaits future discovery and description.

PMID: 22824419 [PubMed – in process]

Genetic characterisation of Cryptosporidium and Giardia from dairy calves: discovery of species/genotypes consistent with those found in humans.

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Genetic characterisation of Cryptosporidium and Giardia from dairy calves: discovery of species/genotypes consistent with those found in humans.
Infect Genet Evol. 2012 Dec;12(8):1984-93
Authors: Abeywardena…

The Plasmodium apicoplast genome: conserved structure and close relationship of P. ovale to rodent malaria parasites.

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The Plasmodium apicoplast genome: conserved structure and close relationship of P. ovale to rodent malaria parasites.
Mol Biol Evol. 2012 Sep;29(9):2095-9
Authors: Arisue N, Hashimoto T, Mitsui H, Palacpac N…

A review of the infection, genetics, and evolution of Neospora caninum: from the past to the present.

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A review of the infection, genetics, and evolution of Neospora caninum: from the past to the present.
Infect Genet Evol. 2013 Jan;13:133-50
Authors: Goodswen SJ, Kennedy PJ, Ellis JT
Abstract

Sulfadoxine-pyrimethamine resistance in Plasmodium falciparum: a zoomed image at the molecular level within a geographic context.

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Sulfadoxine-pyrimethamine resistance in Plasmodium falciparum: a zoomed image at the molecular level within a geographic context.
Acta Trop. 2013 Feb;125(2):163-90
Authors: Abdul-Ghani R, Farag HF, Allam AF