ANALYSIS OF INFRASPECIFIC VARIATION AMONG 5 STRAINS OF EIMERIA-MAXIMAFROM NORTH-AMERICA

Two laboratory strains from the eastern shore of Maryland 15 years ago and from an Ontario broiler house 23 years ago and three recent field strains of Eimeria maxima (isolated in Maryland, North Carolina and F lorida) were examined for phenotypic and genotypic variation using pro tein profiles, random amplified polymorphic DNA-PCR analysis and DNA s equences obtained from the internal transcribed spacer regions of the rRNA genes. Staining profiles obtained by one-dimensional SDS-PAGE of sporozoite proteins were identical in all five strains. Using random a mplified polymorphic DNA-PCR analysis with high %G-C content decamers as primers, we were able to confirm that the five strains are all E. m axima, but were unable to discern any relationships among them because of the limited number of shared polymorphisms identified. In contrast , cloning and sequencing of the internal transcribed spacer-1, 5.8S rD NA and internal transcribed spacer-2 regions of the rRNA genes provide d sufficient sequence information to infer phylogenetic relationships among the strains. Almost all of the infraspecific variation was locat ed in the internal transcribed spacer regions. Only two base changes w ere identified within the 5.8S rRNA gene. Evolutionary relationships a mong the strains inferred using parsimony analysis of the aligned inte rnal transcribed spacer sequences were well supported, but the hypothe sised relationships did not correlate well with the demonstrated immun ological cross-reactivities of these strains. (C) 1998 Australian Soci ety for Parasitology. Published by Elsevier Science Ltd.