Isolation of Sarcocystis neurona from an opossum (Didelphis albiventris) in Argentina

MORÉ, G.; RAMBEAUD, M.; BRAUN, F.; CAMPERO, L.M.; WALKOSKY, A.; VENTURINI, M.C.

Buenos Aires

Conferencia; 10th International Equine Infectious Diseases Conference (IEIDC X); 2016

Sarcocystis neurona is an Apicomplexan parasite which affects a wide range of animal hosts. This protozoan is the main cause of equine protozoal myeloecephalitis (EPM) inWestern Hemisphere horses. The parasite reproduces sexually in the intestine of definitive hosts (DH) and asexually in tissues of intermediate and aberrant hosts. The geographical distribution of S. neurona isrelated with the distribution its definitive hosts, the opossums Didelphis virginiana and D. albiventris. A recent serological study conducted in Argentinean horses using S. neurona antigen revealed an overall seroprevalence of 26.1%. However, the parasite has not been isolated in Argentina. Tissues from an opossum (D.albiventris) hunted by dogs in a farm from the central region ofBuenos Aires province were collected. Horses raised in the farm showed a 50% (10/20) S. neurona seroprevalence. One seropositive horse developed neurological signs and evidenced clinical improvement after a 2 month treatment with Ponazuril. A complete necropsy of the opossum was conducted and the intestinalmucosal scraping was subjected to a parasitological study with sucrose solution. A high amount of Sarcocystis spp. oocysts/sporocysts were observed (Fig. 1). DNA was extracted from concentrated oocysts with a commercial kit (ZR Fecal DNA, Zymo Research). The sample was identified as S. neurona by specific PCR-restriction fragment length polymorphism (RFLP) and by sequencing of a fragment of the 18S rRNA gene. Approximately 5x105 oocysts were subjected to a pepsin-HCl digestion followed by a physical disruption. Released sporozoites were used to infect fresh BM cell cultures, maintained by 3 passages during 2 months and further preserved in liquid nitrogen. This study represents the first isolation of S. neurona in Argentina. Further studies will be conducted in order to identify antigen expression as well as to compare genetic characteristics between the isolated strain and reference strains.