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Updated: Nov 25, 2025
Studying Cryptosporidium Infection in 3D Tissue-derived Human Organoid Culture Systems by Microinjection
Published on: September 14, 2019
Comparative genomic analysis of the principal Cryptosporidium species that infect humans
Laura M Arias-Agudelo1, Gisela Garcia-Montoya1, Felipe Cabarcas1,2
1Centro Nacional de Secuenciación Genómica - CNSG, Sede de Investigación Universitaria - SIU, Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad de Antioquia, Medellin, Antioquia, Colombia.
Abstract:
Cryptosporidium parasites are ubiquitous and can infect a broad range of vertebrates and are considered the most frequent protozoa associated with waterborne parasitic outbreaks. The intestine is the target of three of the species most frequently found in humans: C. hominis, C. parvum, and. C. meleagridis. Despite the recent advance in genome sequencing projects for this apicomplexan, a broad genomic comparison including the three species most prevalent in humans have not been published so far. In this work, we downloaded raw NGS data, assembled it under normalized conditions, and compared 23 publicly available genomes of C. hominis, C. parvum, and C. meleagridis. Although few genomes showed highly fragmented assemblies, most of them had less than 500 scaffolds and mean coverage that ranged between 35X and 511X. Synonymous single nucleotide variants were the most common in C. hominis and C. meleagridis, while in C. parvum, they accounted for around 50% of the SNV observed. Furthermore, deleterious nucleotide substitutions common to all three species were more common in genes associated with DNA repair, recombination, and chromosome-associated proteins. Indel events were observed in the 23 studied isolates that spanned up to 500 bases. The highest number of deletions was observed in C. meleagridis, followed by C. hominis, with more than 60 species-specific deletions found in some isolates of these two species. Although several genes with indel events have been partially annotated, most of them remain to encode uncharacterized proteins.
Insights
Cryptosporidium parasites cause frequent waterborne outbreaks. This study compared 23 genomes of Cryptosporidium hominis, Cryptosporidium parvum, and Cryptosporidium meleagridis, revealing key genetic variations and deletions.
Area of Science:
- Genomics
- Parasitology
- Molecular Biology
Background:
- Cryptosporidium is a ubiquitous protozoan parasite responsible for frequent waterborne outbreaks.
- Three species, C. hominis, C. parvum, and C. meleagridis, are most prevalent in human infections.
- A comprehensive genomic comparison of these three key species has been lacking.
Purpose of the Study:
- To perform a broad genomic comparison of 23 publicly available genomes of C. hominis, C. parvum, and C. meleagridis.
- To identify and analyze genetic variations, including single nucleotide variants (SNVs) and indel events.
- To investigate genes affected by these variations, particularly those related to DNA repair and uncharacterized proteins.
Main Methods:
- Downloaded and assembled raw next-generation sequencing (NGS) data for 23 Cryptosporidium genomes.
- Normalized assembly conditions and analyzed genome quality metrics (scaffold number, mean coverage).
- Compared synonymous and deleterious single nucleotide variants (SNVs) and insertion-deletion (indel) events across species.
Main Results:
- Most assemblies had <500 scaffolds and mean coverage between 35X-511X.
- Synonymous SNVs were most common in C. hominis and C. meleagridis; they comprised ~50% of SNVs in C. parvum.
- Deleterious substitutions in all three species were enriched in DNA repair and chromosome-associated genes. Deletions up to 500 bases were observed, with C. meleagridis and C. hominis showing >60 species-specific deletions.
Conclusions:
- This comparative genomic analysis provides insights into the genetic diversity of prevalent human Cryptosporidium species.
- Identified genetic variations, particularly deletions in C. hominis and C. meleagridis, may contribute to species-specific adaptations or virulence.
- Further characterization of genes affected by indels is needed to understand their functional roles.
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