Fluorescence analysis detects gp60 subtype diversity in Cryptosporidium infections

• Published in: Infection, genetics and evolution genetics and evolution, 2011-08, Vol.11 (6), p.1388-1395
• Main Authors: Waldron, L.S., Power, M.L.
• Format: Article
• Language: English
• Subjects: Animals; Antigens, Protozoan - genetics; Antigens, Protozoan - immunology; Biological and medical sciences; Cattle; Cattle Diseases - parasitology; Cryptosporidiosis; Cryptosporidiosis - parasitology; Cryptosporidiosis - veterinary; Cryptosporidium; Cryptosporidium - classification; Cryptosporidium - genetics; Cryptosporidium - immunology; Cryptosporidium hominis; Cryptosporidium parvum; DNA Probes; epidemiology; Epidemiology. Vaccinations; Fluorescence; Fluorescent Dyes; General aspects; genes; Genetic Variation; glycoproteins; Gp60; hosts; Human protozoal diseases; Humans; immune system; Infection; Infectious diseases; Medical sciences; Mice; Molecular Sequence Data; Molecular Typing - methods; Parasitic diseases; Polymerase Chain Reaction - methods; Polymorphism, Restriction Fragment Length; Protozoal diseases; Reproducibility of Results; sequence analysis; Spectrometry, Fluorescence - methods; T-RFLP
• ISSN: 1567-1348; 1567-7257
• DOI: 10.1016/j.meegid.2011.05.008

► The hypervariable gp60 gene is used to identify Cryptosporidium subtypes. ► Exposure to the hosts’ immune system supports the hypothesis of selection pressure on this gene. ► T-RFLP detected subtype variability within a human infection and mouse passages. ► This study showed that the ratio of subtype populations differs between infections. 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.