Detection and genotyping of oocysts of Cryptosporidium parvum by real-time PCR and melting curve analysis

J Clin Microbiol. 2002 Sep;40(9):3237-44. doi: 10.1128/JCM.40.9.3237-3244.2002.

Abstract

Several real-time PCR procedures for the detection and genotyping of oocysts of Cryptosporidium parvum were evaluated. A 40-cycle amplification of a 157-bp fragment from the C. parvum beta-tubulin gene detected individual oocysts which were introduced into the reaction mixture by micromanipulation. SYBR Green I melting curve analysis was used to confirm the specificity of the method when DNA extracted from fecal samples spiked with oocysts was analyzed. Because C. parvum isolates infecting humans comprise two distinct genotypes, designated type 1 and type 2, real-time PCR methods for discriminating C. parvum genotypes were developed. The first method used the same beta-tubulin amplification primers and two fluorescently labeled antisense oligonucleotide probes spanning a 49-bp polymorphic sequence diagnostic for C. parvum type 1 and type 2. The second genotyping method used SYBR Green I fluorescence and targeted a polymorphic coding region within the GP900/poly(T) gene. Both methods discriminated between type 1 and type 2 C. parvum on the basis of melting curve analysis. To our knowledge, this is the first report describing the application of melting curve analysis for genotyping of C. parvum oocysts.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Benzothiazoles
  • Cattle
  • Cryptosporidiosis / parasitology*
  • Cryptosporidium parvum / classification*
  • Cryptosporidium parvum / genetics
  • Cryptosporidium parvum / growth & development
  • Cryptosporidium parvum / isolation & purification*
  • Diamines
  • Fluorescent Dyes
  • Genotype
  • Humans
  • Organic Chemicals*
  • Polymerase Chain Reaction / methods*
  • Quinolines
  • Sensitivity and Specificity
  • Temperature*
  • Tubulin / genetics

Substances

  • Benzothiazoles
  • Diamines
  • Fluorescent Dyes
  • Organic Chemicals
  • Quinolines
  • Tubulin
  • SYBR Green I