2 ENCEPHALITOZOON-CUNICULI STRAINS OF HUMAN-ORIGIN ARE INFECTIOUS TO RABBITS

The microsporidian Encephalitozoon cuniculi can infect a wide variety of mammals including man. In this study, E. cuniculi isolates of anima l origin were compared with 6 isolates obtained from HIV-infected pati ents. Based on results of Western blot analysis, random amplified poly morphic DNA (RAPD) and the sequence of the rDNA internal transcribed s pacer (ITS) the isolates were classified into 3 groups with the repeat ed element 5'GTTT-3' in the ITS being a reliable genetic marker. Five isolates from Swiss patients were found to be homologous to isolates f rom Swiss rabbits (strain I). The sixth isolate from a patient from Me xico differed by all methods and could be attributed to E. cuniculi st rain III that has been described from 2 dogs from the USA. All of thes e isolates were distinguished from isolates from blue foxes from Norwa y (strain II). Intraspecific nucleotide divergence of the SSU rRNA gen e 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. h ellem isolates. Groups of 2 rabbits were infected by oral inoculation of 10(7) E. cuniculi spores (2 isolates from strain I of human and rab bit 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 v arious hosts is feasible.