Fluorescence analysis detects gp60 subtype diversity in Cryptosporidium infections
1Department of Biological Sciences, Macquarie University, Sydney, NSW 2109, Australia. liette.waldron@mq.edu.au
Abstract:
Ninety percent of human cryptosporidiosis infections are attributed to two species; the anthroponotic Cryptosporidium hominis and the zoonotic Cryptosporidium parvum. Sequence analysis of the hypervariable gp60 gene, which is used to classify Cryptosporidium to the subtype level, has highlighted extensive intra-species diversity within both C. hominis and C. parvum. The gp60 has also facilitated contamination source tracking and increased understanding of the epidemiology of cryptosporidiosis. Two surface glycoproteins, the gp40 and gp15 are encoded in the gp60 gene; both are exposed to the hosts' immune system and play a pivotal role in the disease initiation process. The extent of genetic diversity observed within the gp60 would support the hypotheses of significant selection pressure placed on the gp40 and gp15. This study used a dual fluorescent terminal-restriction fragment length polymorphism (T-RFLP) analysis to investigate the genetic diversity of Cryptosporidium subtype populations in a single host infection. Terminal-RFLP showed subtype variation within one human Cryptosporidium sample and mouse samples from seven consecutive passages with C. parvum. Furthermore, this was the first study to show that differences in the ratio of subtype populations occur between infections. T-RFLP has provided a novel platform to study infection populations and to begin to investigate the impact of the hosts' immune system on the gp60 gene.
Insights
This study reveals genetic diversity within Cryptosporidium subtypes, particularly in the gp60 gene, impacting cryptosporidiosis epidemiology. Terminal-restriction fragment length polymorphism (T-RFLP) analysis demonstrated subtype variation and differences in population ratios between infections.
Area of Science:
- * Molecular Parasitology
- * Infectious Disease Epidemiology
- * Genomic Diversity Analysis
Background:
- * Cryptosporidiosis is a significant human enteric disease caused by Cryptosporidium parasites.
- * The gp60 gene is crucial for Cryptosporidium subtyping and epidemiological tracking.
- * Intra-species diversity in the gp60 gene suggests immune selection pressure on surface glycoproteins.
Purpose of the Study:
- * To investigate the genetic diversity of Cryptosporidium subtype populations within single host infections.
- * To explore the utility of terminal-restriction fragment length polymorphism (T-RFLP) for analyzing Cryptosporidium population dynamics.
- * To understand the impact of host immune systems on the gp60 gene diversity.
Main Methods:
- * Dual fluorescent terminal-restriction fragment length polymorphism (T-RFLP) analysis was employed.
- * Genetic diversity was assessed in human and mouse Cryptosporidium samples.
- * Analysis included samples from seven consecutive passages of Cryptosporidium parvum in mice.
Main Results:
- * T-RFLP analysis revealed significant subtype variation within a single human Cryptosporidium infection.
- * Subtype variation and changes in population ratios were observed across serial passages in mouse models.
- * This study provides the first evidence of differing subtype population ratios between distinct infections.
Conclusions:
- * The gp60 gene exhibits substantial intra-species diversity, reflecting host-pathogen interactions.
- * T-RFLP is a valuable tool for studying the genetic diversity and population structure of Cryptosporidium infections.
- * Further research using T-RFLP can elucidate the influence of host immunity on gp60 gene evolution.
