Inter- and intra-species karyotype variations among microsporidia of the genus Encephalitozoon as determined by pulsed-field gel electrophoresis

Disseminated infections due to microsporidia of the genus Encephalitozoon a re detected increasingly, especially in patients with AIDS. Identification of microsporidia can be achieved by a variety of immunological and molecula r methods. This study evaluates the feasibility of pulsed-field gel electro phoresis (PFGE) for the analysis of karyotypes of the 3 known species of th is genus (Encephalitozoon cuniculi, Encephalitozoon hellem and Encephalitoz oon intestinalis) and of 2 of the 3 known E. cuniculi strains (strains I an d III). Eleven chromosomal DNA bands were resolved for E, cuniculi and 10 c hromosomal DNA bands for E. hellem and E, intestinalis, with molecular size s ranging from 231 to 320 kb, from 197 to 288 kb and from 195 to 285 kb, re spectively, resulting in estimated genome sizes of about 3.0 Mb, 2.5 Mb and 2.4 Mb. Different PFGE chromosomal banding patterns indicate that not only E, cuniculi, as previously described, but also E. hellem, represent a hete rogeneous entity. PFGE is a valuable method of evaluating inter- and intra- species variations among Encephalitozoon species that may enable the identi fication of environmental sources of infection and modes of transmission.