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Two Encephalitozoon cuniculi strains of human origin are infectious to rabbits
Abstract:
The microsporidian Encephalitozoon cuniculi can infect a wide variety of mammals including man. In this study, E. cuniculi isolates of animal origin were compared with 6 isolates obtained from HIV-infected patients. Based on results of Western blot analysis, random amplified polymorphic DNA (RAPD) and the sequence of the rDNA internal transcribed spacer (ITS) the isolates were classified into 3 groups with the repeated element 5'GTTT-3' in the ITS being a reliable genetic marker. Five isolates from Swiss patients were found to be homologous to isolates from Swiss rabbits (strain I). The sixth isolate from a patient from Mexico differed by all methods and could be attributed to E. cuniculi strain III that has been described from 2 dogs from the USA. All of these isolates were distinguished from isolates from blue foxes from Norway (strain II). Intraspecific nucleotide divergence of the SSU rRNA gene of E. cuniculi belonging to the 3 strains was in the same low range (0.00-0.15%) as was found for the corresponding sequence of 2 E. hellem isolates. Groups of 2 rabbits were infected by oral inoculation of 10(7) E. cuniculi spores (2 isolates from strain I of human and rabbit origin, 1 from strain III) as shown by antibody responses and the re-isolation of the parasites from brain material. The results provide further evidence that per oral transmission of the parasite between various hosts is feasible.
Insights
Encephalitozoon cuniculi, a microsporidian parasite, infects humans and animals. Genetic analysis revealed three distinct strains, with evidence of oral transmission between hosts, highlighting its zoonotic potential.
Area of Science:
- Parasitology
- Microbiology
- Genetics
Background:
- The microsporidian Encephalitozoon cuniculi is a known pathogen affecting diverse mammalian hosts, including humans.
- Understanding the genetic diversity and transmission routes of E. cuniculi is crucial for public health, especially in immunocompromised individuals.
Purpose of the Study:
- To genetically characterize Encephalitozoon cuniculi isolates from animal and human origins.
- To identify reliable genetic markers for differentiating E. cuniculi strains.
- To investigate the feasibility of oral transmission of E. cuniculi between hosts.
Main Methods:
- Western blot analysis
- Random Amplified Polymorphic DNA (RAPD) analysis
- rDNA internal transcribed spacer (ITS) sequencing
- SSU rRNA gene sequencing
- Oral inoculation of rabbits with E. cuniculi spores
Main Results:
- E. cuniculi isolates were classified into three distinct genetic groups (strains I, II, and III) based on molecular analyses.
- The repeated element 5'GTTT-3' in the ITS was identified as a reliable genetic marker for strain differentiation.
- Isolates from Swiss patients and rabbits belonged to strain I, while an isolate from a Mexican patient matched strain III (previously found in dogs).
- Isolates from Norwegian blue foxes represented strain II.
- Infection was confirmed in rabbits inoculated orally with E. cuniculi spores from strains I and III, demonstrating successful per-oral transmission.
Conclusions:
- Genetic analysis, particularly ITS sequencing, effectively differentiates E. cuniculi strains.
- E. cuniculi exhibits significant genetic diversity, with distinct strains circulating in different host populations.
- Per-oral transmission of E. cuniculi is a viable route for infection and spread between various hosts, underscoring its zoonotic potential.