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DNA sequence similarity between California isolates of Cryptosporidium parvum
G Pereira M das1, E R Atwill, M R Crawford
1Veterinary Medicine Teaching and Research Center, School of Veterinary Medicine, University of California, Davis, Tulare 93274, USA.
Abstract:
We evaluated whether nucleic acid amplification with primers specific for Cryptosporidium parvum followed by automated DNA sequence analysis of the PCR amplicons could differentiate between California isolates of C. parvum obtained from livestock, humans, and feral pigs. Almost complete sequence identity existed among the livestock isolates and between the livestock and human isolates. DNA sequences from feral pig isolates differed from those from livestock and humans by 1.0 to 1.2%. The reference sequence obtained by Laxer et al. (M. A. Laxer, B. K. Timblin, and R. J. Patel, Am. J. Trop. Med. Hyg. 45:688-694, 1991.) differed from California isolates of C. parvum by 1.8 to 3.2%. These data suggest that DNA sequence analysis of the amplicon of Laxer et al. does not allow for differentiation between various strains of C. parvum or that our collection of isolates obtained from various hosts from across California was limited to one strain of C. parvum.
Insights
DNA sequencing of Cryptosporidium parvum (C. parvum) isolates from California showed minimal genetic variation. This suggests current methods may not distinguish between C. parvum strains from different hosts.
Area of Science:
- Veterinary Parasitology
- Molecular Biology
- Genetics
Background:
- Cryptosporidium parvum is a significant protozoan parasite affecting livestock and humans.
- Understanding genetic diversity within C. parvum is crucial for epidemiological studies and control strategies.
- Previous studies have explored molecular methods for C. parvum typing.
Purpose of the Study:
- To assess the utility of DNA sequencing for differentiating C. parvum isolates from various California hosts.
- To investigate the genetic relatedness of C. parvum from livestock, humans, and feral pigs.
Main Methods:
- Nucleic acid amplification using primers specific for C. parvum.
- Automated DNA sequence analysis of Polymerase Chain Reaction (PCR) amplicons.
- Comparison of sequences from isolates obtained from livestock, humans, and feral pigs.
Main Results:
- Near-complete sequence identity was observed among livestock isolates and between livestock and human isolates.
- Feral pig C. parvum isolates showed minor sequence differences (1.0-1.2%) compared to livestock and human isolates.
- The reference sequence differed from California isolates by 1.8-3.2%.
Conclusions:
- DNA sequence analysis, as applied in this study, may not be sufficient to differentiate C. parvum strains.
- The limited genetic variation observed could indicate a single C. parvum strain prevalence in the studied California population or limitations in the analytical method.