A group of Giardia lamblia variant-specific surface protein (VSP) genes with nearly identical 5′ regions

Yang, Yong-Min; Adam, Rodney D.

doi:10.1016/0166-6851(95)02514-6

Cited by 18 publications

(12 citation statements)

References 13 publications

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“…This close relationship of most GS/M-83-H7-derived VSP sequences further supported a previous hypothesis suggesting that the formation of the different Giardia vsp gene repertoires is the consequence of ancestral combinatorial processes that included serial gene duplication, mutation and/or recombination events within the individual isolates (4,35,36). However, since four vsp cDNA clones identified turned out to be rather distinct from the assemblage B-type vsp gene sequences, this ancestral gene duplication model may be insufficient to explain FIG.…”

Section: Discussionsupporting

confidence: 67%

vspGene Expression byGiardia lambliaClone GS/M-83-H7 during Antigenic Variation In Vivo and In Vitro

et al. 2001

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Giardia lamblia infections are associated with antigenic variation of the parasite, which is generated by a continuous change of the variant-specific surface proteins (VSPs). Many investigations on the process of antigenic variation were based on the use of G. lamblia clone GS/M-83-H7, which expresses VSP H7 as its major surface antigen. In the present study, mice were infected with the aforementioned clonal line to investigate vsp gene expression during the complex process of antigenic variation of the parasite.

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Section: Discussionsupporting

confidence: 67%

vspGene Expression byGiardia lambliaClone GS/M-83-H7 during Antigenic Variation In Vivo and In Vitro

et al. 2001

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“…However, subsequent data have shown that these recombination events can be explained by changes in repeat copy number for the repeat-containing vsp genes (355)(356)(357)(358) Other than changes in repeat copy number, chromosome-mapping studies of the vspA6 and vspC5 genes have revealed no changes in genomic location and organization in isolates where a particular vsp gene is expressed or not expressed (356,358). This indicates that antigenic variation does not occur by moving the vsp genes into expression sites.…”

Section: Genomic Organization Of the Vsp Genes And Potential Mechanismentioning

confidence: 96%

“…Therefore, it is of interest to know whether the vsp genes are telomeric and whether there are genomic rearrangements associated with antigenic variation. Current data indicate that most of the vsp genes are not telomere associated (355)(356)(357). The vspA6 gene is not found in the 150-and 240-kb NotI telomeric fragments of chromosome 4 (356), and the vsp conserved region does not hybridize to these regions (Adam, unpublished).…”

Section: Genomic Organization Of the Vsp Genes And Potential Mechanismentioning

confidence: 99%

“…For example, vspC5 demonstrates near identity to vspC5-S2 from approximately Ϫ150 to ϩ94 and to vspC5-S1 from Ϫ150 to ϩ130 (355). A more complete understanding of the vsp repertoire and gene organization will be available when the sequences obtained as part of the Giardia genome project have been assembled.…”

Section: Genomic Organization Of the Vsp Genes And Potential Mechanismentioning

confidence: 99%

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Biology ofGiardia lamblia

2001

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Giardia lamblia is a common cause of diarrhea in humans and other mammals throughout the world. It can be distinguished from other Giardia species by light or electron microscopy. The two major genotypes of G. lamblia that infect humans are so different genetically and biologically that they may warrant separate species or subspecies designations. Trophozoites have nuclei and a well-developed cytoskeleton but lack mitochondria, peroxisomes, and the components of oxidative phosphorylation. They have an endomembrane system with at least some characteristics of the Golgi complex and encoplasmic reticulum, which becomes more extensive in encysting organisms. The primitive nature of the organelles and metabolism, as well as small-subunit rRNA phylogeny, has led to the proposal that Giardia spp. are among the most primitive eukaryotes. G. lamblia probably has a ploidy of 4 and a genome size of approximately 10 to 12 Mb divided among five chromosomes. Most genes have short 5′ and 3′ untranslated regions and promoter regions that are near the initiation codon. Trophozoites exhibit antigenic variation of an extensive repertoire of cysteine-rich variant-specific surface proteins. Expression is allele specific, and changes in expression from one vsp gene to another have not been associated with sequence alterations or gene rearrangements. The Giardia genome project promises to greatly increase our understanding of this interesting and enigmatic organism

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“…This intestine resident parasite species contains approximately 190 homologous, variant-specific surface protein ( vsp ) genes dispersed throughout the genome. Furthermore, multiple copies of a particular vsp gene might be tandemly arranged on a chromosome region [167], as well as duplication of upstream and downstream regions from one vsp to another [168]. Importantly and in contrast to the general trend in protozoa described above, the vsp genes are predominantly non-subtelomeric [169].…”

Section: Roles Of Sir2 Proteins In Protozoamentioning

confidence: 96%