title: A 63 kDa VSP9B10A-like protein expressed in a C-8 Giardia duodenalis Mexican clone.
abstract: BACKGROUND
  It is well documented that Giardia duodenalis undergoes surface antigenic variation both in vivo and in vitro. Proteins involved have been characterized and referred to as VSP (variable surface protein).
  
  
  METHODS
  Two cloned cDNA inserts of 0.45 and 1.95 kb were obtained from G. duodenalis expression library and sequenced. Comparison sequence analyses were made against Genbank. PCR analysis was performed on G. duodenalis isolates to identify isolates bearing genes encoding such a peptide. Specific antiserum was prepared against 450-bp encoded peptide and tested by Western blot, immunofluorescence, and inhibition of adhesion of G. duodenalis to target cells.
  
  
  RESULTS
  We cloned and characterized a G. duodenalis 450-bp DNA fragment; its DNA sequence analysis revealed that this fragment displayed 99% identity with vsp9B10A gene. Predicted amino acid sequence for this fragment also had significant (99%) identity to VSP9B10A. A second 1.95-kb insert, which encompassed the 450-bp cDNA fragment, was also isolated; its DNA and amino acid sequence displayed 99.5% identity with vsp9B10A gene and 99.2% with the corresponding inferred protein, respectively. This inferred protein contained 24 Cys-X-X-Cys motifs and long ORF of 642 aminoacids. PCR analysis showed that DNA sequence encoding a fragment of this gene was present in P1, CIEA:0487:2-C-8 clone and in INP:180800-B2 G. duodenalis human isolates, while it was absent in sheep isolate of G. duodenalis INP:150593-J10.
  
  
  CONCLUSIONS
  Immunofluorescence analysis using antibodies raised against the peptide encoded by 450-bp fragment showed that expression of this epitope varies on trophozoite surface of the C-8 Mexican clone and is involved in parasite adhesion to target epithelial cells.
authors.affiliation: Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico National (Cinvestav del IPN), Mexico City, Mexico.
authors.forename: Rosa María
authors.initials: RM
authors.lastname: Bermúdez-Cruz
authors.forename: Guadalupe
authors.initials: G
authors.lastname: Ortega-Pierres
authors.forename: Víctor
authors.initials: V
authors.lastname: Ceja
authors.forename: Ramón
authors.initials: R
authors.lastname: Coral-Vázquez
authors.forename: Rocío
authors.initials: R
authors.lastname: Fonseca
authors.forename: Lourdes
authors.initials: L
authors.lastname: Cervantes
authors.forename: Alejandra
authors.initials: A
authors.lastname: Sánchez
authors.forename: Francisco
authors.initials: F
authors.lastname: Depardón
authors.forename: George
authors.initials: G
authors.lastname: Newport
authors.forename: Cecilia
authors.initials: C
authors.lastname: Montañéz
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000953:Antigens, Protozoan / Q000737:chemistry; D001483:Base Sequence; D015153:Blotting, Western; D002448:Cell Adhesion; D002460:Cell Line; D002675:Child, Preschool; D003001:Cloning, Molecular; D004247:DNA / Q000737:chemistry; D018076:DNA, Complementary / Q000378:metabolism; D004285:Dogs; D000939:Epitopes / Q000737:chemistry; D015723:Gene Library; D014644:Genetic Variation; D005872:Giardia / Q000378:metabolism*; D005873:Giardiasis / Q000276:immunology; D006801:Humans; D007700:Kinetics; D008800:Mexico; D051379:Mice; D008807:Mice, Inbred BALB C; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D016133:Polymerase Chain Reaction; D017434:Protein Structure, Tertiary; D015800:Protozoan Proteins / Q000737:chemistry; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D012756:Sheep; D013997:Time Factors
chemical_list: D000953:Antigens, Protozoan; D018076:DNA, Complementary; D000939:Epitopes; D010455:Peptides; D015800:Protozoan Proteins; D011993:Recombinant Fusion Proteins; D004247:DNA