Sequence comparison of Sarcocystis neurona surface antigen from multiple isolates

Sarcocystis neurona major surface antigen gene 1 (SAG1) shows evidence of having evolved under positive selection pressure

“…In this context, investigation of the extent of the genetic polymorphism in SAG1 of the protozoan S. neurona, and the processes that maintain the observed diversity, is a matter of epidemiological and evolutionary significance. Previous study has addressed the diversity of SAG1 and reported 73-100% sequence homology among S. neurona isolates (Hyun et al 2003). In the present study, similar nucleotide diversity was identified in SAG1 and nucleotide sequence variation was observed in almost all of the gene, particularly in the intron region.…”

“…Each vertical line marks the location of a nucleotide or amino acid difference between the two alleles sequence. (C) Nucleotide alignment of two SAG1 sequences representing the two alleles of S. neurona SAG1 that shows the predicted cleavage site for a signal peptide (underlined) as identified by Hyun et al (2003). Dots indicate sequence identity and dashes alignment gaps b 1.…”

“…neurona has an immunodominant surface antigen gene 1 (SAG1), which appears to occur as a single copy and encodes a major antigenic surface protein of about 29 kDa (Ellison et al 2002). SAG1 has been suggested as a diagnostic marker for phylogenetically related Sarcocystis species from different geographical areas (Hyun et al 2003). The genetically closely related organism Toxoplasma gondii has an immunodominant major surface antigen P30, which has been extensively studied with a view to the development of a vaccine (Bonenfant et al 2001;Letscher-Bru et al 2003).…”

Equine Protozoal Myeloencephalitis

“…91 This is consistent with previous work, which has demonstrated that the 30-kD antigen (i.e., snSAG-1) was inconsistently reported. 5,8 A stall-side S. neurona screening test is currently available for the confirmation of antibodies to S. neurona (S. neurona, Endocrine Technologies) in serum. This test uses the ELISA platform and snSag-1 as the antigen, as well as a second testing "spot" for mixed surface proteins.…”

“…3,4 Since that time, the organism has been cultured from several other ataxic horses, and a variety of strains of the parasite have been described. [5][6][7][8][9] In addition, S. neurona or an S. neurona-like organism has been cultured from the CNS of a number of other species including the zebra, 10 domestic cat, 11 Canadian lynx, 12 sea otter, 13,14 straw-necked ibis, 15 mink, raccoon, and skunk. [16][17][18] Experimental inoculation of horses with S. neurona has been shown to induce a syndrome of neurologic disease consistent with field cases, and it is clear that S. neurona is the major cause of the disease referred to as EPM.…”