Location: Animal Parasitic Diseases
Title: Is sporozoite refractile body protein expression different in Eimeria acervulina sporozoites isolated from non-immune versus immune chickens? Authors
Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: June 9, 2013
Publication Date: N/A
Technical Abstract: A hallmark of Eimeria infection in avians is the establishment of immunity against clinical signs of coccidiosis. Resistant birds experience improved weight gain and feed conversion efficiency and lack intestinal lesions. Oocysts excretion is reduced, but not eliminated, in such immune chickens. The purpose of this study was to determine whether the immune status of chickens influenced the expression of an immunodominant refractile body antigen in sporozoites of Eimeria acervulina. To do so, sporozoite DNA and RNA was isolated after primary and 3 secondary challenges and subjected to PCR and RT-PCR amplification of a sequence coding for an immunodominant refractile body (RB) protein. DNA sequencing of clones from these amplifications revealed polymorphism (3 isoforms) in the repeat region of the RB protein, such that a stop codon was introduced into the sequence causing a premature termination of RNA transcription (100 bp upstream). All 3 isoforms were expressed in Escherichia coli, and antisera were prepared against full-length and truncated proteins. Immunofluorescence staining of E. acervulina sporozoites with these sera revealed strong recognition of the mature, full length RB isoform, but no staining of the truncated isoforms. While preliminary data suggest differential expression of these isoforms in immune vs. naïve chickens, more research is necessary to confirm this finding, and to determine if, within populations of E. acervulina sporozoites, different isoforms generally coexist. It also remains to be determined whether immune pressure is necessary and sufficient to engender differential expression of these isoforms.