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Keywords:

  • Cryptosporidium ;
  • assay development;
  • microneme;
  • MIC1;
  • ML-2;
  • on-chip capillary electrophoresis

Summary

Cryptosporidium are ubiquitous and significant enteropathogens of all classes of vertebrates and a major cause of human morbidity and mortality worldwide. Of the 24 recognized species, the zoonotic Cryptosporidium parvum and the host-specific Cryptosporidium hominis cause the majority of cases of human cryptosporidiosis. Here, we report on structural and transcriptional variability between Cparvum and Chominis at the MIC1 locus, which encodes a microneme localized thrombospondin-like domain containing protein previously demonstrated to be critical for host cell infection by Cparvum. We demonstrate, using reverse transcription quantitative PCR with the aid of genomic data from the EuPathDB site, that the transcribed product in Chominis is both truncated and significantly down-regulated in the sporozoite. We hypothesize that CpMIC1 may be a genetic factor involved in facilitating the wider host range of C. parvum in comparison with the specific host range of C. hominis. Furthermore, we show that the presence of a microsatellite (ML-2) within the Cparvum MIC-1 locus enables the development of a PCR marker that can rapidly distinguish the zoonotic C. parvum from Chominis and other significant human infectious Cryptosporidium species due to reproducible PCR slippage across the ML-2 microsatellite. Additionally, we demonstrate that this locus is tightly linked to the GP60 locus, a locus commonly used in the genetic characterization of C. parvum and Chominis isolates. This marker should provide a robust and additional tool to aid in the rapid identification of C. parvum from other Cryptosporidium species.