Contingent, non-neutral evolution in a multicellular parasite: natural selection and gene conversion in the Echinococcus granulosus antigen B gene family

Haag, Karen Luisa; Alves-Junior, Leonardo; Zaha, Arnaldo; Ayala, Francisco J.

doi:10.1016/j.gene.2004.02.027

Cited by 58 publications

(68 citation statements)

References 26 publications

(24 reference statements)

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“…We would speculate that these contradictions arise, mainly, because of use of a different serum collection. Regarding that, we still do not know the level of variation in the subunit composition of AgB at different stages of the metacestode development (12), or how the integrity of the cyst will determine the host exposure to EgMDH (a cytosolic component of E. granulosus), which certainly depends on the extent of parasite cell damage. In the case of the peptide, an intriguing fact was its differential behavior in the different centers.…”

Section: Discussionmentioning

confidence: 99%

Comparative Analysis of the Diagnostic Performance of Six Major Echinococcus granulosus Antigens Assessed in a Double-Blind, Randomized Multicenter Study

Lorenzo¹,

Ferreira

Monteiro

et al. 2005

J Clin Microbiol

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The serodiagnosis of hydatid disease is a valuable instrument for clinical diagnosis and epidemiological surveillance of high-risk populations. In the past decade a wealth of reports on the diagnostic performance of numerous antigens have been produced. However, their diagnostic value has been estimated under different conditions, using different serum collection, therefore precluding their direct comparison. Here we report an unbiased comparison of the same batch of six major E. granulosus antigens, namely, hydatid cyst fluid (HCF), native antigen B (AgB), two recombinant AgB subunits, an AgB-derived synthetic peptide, and recombinant cytosolic malate dehydrogenase from E. granulosus (EgMDH), against the same serum collection. The doubleblind analysis was performed using a standardized protocol and receiver operating characteristic (ROC) data analysis by a network of six South American laboratories. High intercenter reproducibility was attained, and the intralaboratory analysis allowed the comparative ranking of the antigen panel. HCF, AgB, and its AgB8/1 subunit exhibited equivalent diagnostic efficiencies, 81.4% ؎ 0.5%, 81.3% ؎ 0.6%, and 81.9% ؎ 2.0%, respectively; with a more favorable balance toward specificity in the case of the last antigen. The diagnostic efficiencies for the other three antigens were 76.8% ؎ 6.8%, 69.1% ؎ 2.7%, and 66.8% ؎ 2.1%, for the peptide, the AgB8/2 subunit, and the EgMDH, respectively. The study also included an analysis of batch-to-batch variation in the diagnostic performance of different HCF regional preparations. Based on these results, a suggested recommendation on the use of these antigens was drawn.

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Section: Discussionmentioning

confidence: 99%

Comparative Analysis of the Diagnostic Performance of Six Major Echinococcus granulosus Antigens Assessed in a Double-Blind, Randomized Multicenter Study

Lorenzo¹,

Ferreira

Monteiro

et al. 2005

J Clin Microbiol

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“…A total of 24 different AgB-related genomic variants was isolated (Table 1). Since these sequences cluster either with AgB2 or AgB4, we named them EgB2 or EgB4 to adopt consistent nomenclature with Haag et al (2004), followed by the strain (G1-7) and a number representing the variant after a ' v '. Hence, all variants with the same number after the ' v ' have identical nucleotide sequence.…”

Section: Isolation Of Genomic Agb Variantsmentioning

confidence: 99%

“…It has been shown that AgB is encoded by a gene family consisting of AgB1 (Shepherd et al 1991), AgB2 (Fernández et al 1996) and AgB3 (Chemale et al 2001). Recently, 2 additional gene loci related to AgB2 and AgB3 genes named respectively AgB4 and AgB5 have been reported (Haag et al 2004). The comparative analysis of the diagnostic potential of antigens encoded by some of these genes showed that the recombinant antigen AgB2 had the best diagnostic performance (Rott et al 2000 ;Virginio et al 2003).…”

mentioning

confidence: 99%

“…Also, Haag et al (1998 b) found genetic variability in a partial sequence of AgB1 gene among 4 E. granulosus strains. In addition, a high degree of polymorphism of AgB genes was shown in the protoscoleces of a single hydatid cyst (Haag et al 2004). However, the genetic variation and transcription profile of antigen B coding genes in E. granulosus strains has not been systematically analysed so far.…”

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confidence: 99%

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High polymorphism in genes encoding antigen B from human infecting strains of Echinococcus granulosus

et al. 2005

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S U M M A R YEchinococcus granulosus antigen B (AgB) is encoded by a gene family and is involved in the evasion of the host immune response. E. granulosus exists as a number of strains (G1-G10) that differ in biological characteristics. We used PCR-SSCP followed by DNA sequencing to evaluate sequence variation and transcription profile of AgB in 5 E. granulosus strains#. Twenty-four genomic sequences were isolated and clustered in 3 groups related to 2 of the 5 reported AgB genes. AgB4 genes were present in almost all strains, whereas AgB2 were present as functional genes exclusively in G1/G2 cluster, and as non-functional genes in G5 and the G6/G7 cluster, suggesting inter-strain variation. The AgB transcription patterns, analysed by RT-PCR, showed that AgB2 and AgB4 genes were transcribed in G1, while only the AgB4 gene was transcribed in G7 strain. Cysts from the same strain or cluster shared more genomic and cDNA variants than cysts from different strain or cluster. The level of nucleotide and deduced amino acid sequence variation observed is higher than that reported so far for coding genes of other helminths. Neutrality was rejected for AgB2 genes. These data show the genetic polymorphism of antigen-coding genes among genetically characterized strains of E. granulosus.

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“…E. granulosus larvae synthesize a lipoprotein known as antigen B (AgB) in the tegumental cells of the protoscolices and, to a lesser extent, in the laminated and germinal layer of the brood capsules before being secreted in the HCF [3]. AgB is a thermostable lipoprotein that dissociates in SDS-PAGE into 3 bands of [8][9][10][11][12]16, and 24 kDa [4]. It is one of the most abundant parasite antigens in HCF and commonly used in immunodiagnosis of CE [5].…”

Section: Introductionmentioning

confidence: 99%

Genetic Variability of Antigen B among Echinococcus granulosus Egyptian Isolates

et al. 2009

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Genetic polymorphisms of encoding antigen B2 gene (AgB2) in Echinococcus granulosus were studied using PCR-RFLP and DNA sequencing among 20 Egyptian isolates. Five isolates from different host origins (humans, camels, pigs, and sheep) were collected and used. All examined isolates of each host group gave very similar patterns of PCR-RFLP after restriction enzyme digestion with AluI, with the gene size of approximately 140 bp and 240 bp for sheep and human isolates, and approximately 150 bp and 250 bp for pig and camel isolates. No digestion pattern was obtained after incubation of all studied isolates with EcoRI. These results reveal high intra-group homogeneity. DNA sequence analysis highlighted that human infecting strain showed 100% identity with respect to sheep infecting isolate, 96% and 99% with pig and camel infecting isolates, respectively.

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Contingent, non-neutral evolution in a multicellular parasite: natural selection and gene conversion in the Echinococcus granulosus antigen B gene family

Cited by 58 publications

References 26 publications

Comparative Analysis of the Diagnostic Performance of Six Major Echinococcus granulosus Antigens Assessed in a Double-Blind, Randomized Multicenter Study

Comparative Analysis of the Diagnostic Performance of Six Major Echinococcus granulosus Antigens Assessed in a Double-Blind, Randomized Multicenter Study

High polymorphism in genes encoding antigen B from human infecting strains of Echinococcus granulosus

Genetic Variability of Antigen B among Echinococcus granulosus Egyptian Isolates

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