Nc-Argentina LP1: First Neospora caninum bovine isolate in Argentina

CAMPERO L.M.; VENTURINI M.C.; MOORE D.P.; MASSOLA L.; LAGOMARSINO H.; GARCÍA B.; BACIGALUPE D.; RAMBEAUD M.; PARDINI L.; SCHARES G.; CAMPERO C.M.

Gramado

Congreso; XVIII CONGRESSO BRASILEIRO DE PARASITOLOGIA VETERINÁRIA; 2014

Neospora caninum is a protozoan parasite considered a major cause of abortion in cattle. The aims of the work were to obtain and characterize by multilocus-microsatellite analysis new isolates of N. caninum from congenitally infected asymptomatic newborn calves from a large-scale dairy farm in Argentina. Congenital infection was determined by the presence of specific antibodies to N. caninum in sera from dams-calves before colostrum intake using indirect fluorescent antibody test (IFAT). Five clinically normal born calves were euthanized for isolation purposes. Central nervous system (CNS) from calves was processed for histopathological, immunohistochemical (IHC), polymerase chain reaction (PCR) analysis and for in vivo and in vitro isolation assays. In vivo assays used γ-interferon knockout mice, subcutaneously inoculated with CNS from calves. Histopathological findings revealed mixed multifocal meningoencephalitis and epicarditis in all calves. N. caninum DNA was detected from CNS in all the calves by PCR. One mouse (M1) had an IFAT titer of 1:400, presented clinical signs and died 27 days post-inoculation. This mouse was inoculated with CNS from a calf with an IFAT titer of 1:5120. Further passages of CNS from infected mice were performed to keep the isolation in vivo. All mice were analyzed by IFAT and necropsied. Histopathological findings on mice revealed systemic neosporosis showing multiple inflammatory reactions in several tissues associated with parasite detection by IHC in brain, heart, lungs and liver. PCR results were positive for all specimens analyzed from infected mice. In vitro isolation was achieved by infection into a fresh monolayer cell culture with peritoneal liquid containing tachyzoites obtained from infected mice. Multilocus-microsatellite typing was performed confirming the new isolate with a specific genotype (GenBank accession numbers KJ700414 and KJ700413) and was named Nc-Argentina LP1. This is the first bovine isolate of N. caninum in Argentina obtained from a congenitally infected calf from a dairy herd.