Neospora caninum tachyzoites inoculated by the conjunctival route are not vertically transmitted in pregnant cattle:A descriptive study

MOORE D.P. ; ALVAREZ GARCÍA G.; CHIAPPARRONE M.L.; REGIDOR-CERRILLO J.; LINCHINSKY L.H.; DE YANIZ M.G.; ODEÓN A.C. ; ORTEGA-MORA L.M.; CAMPERO C.M.

VETERINARY PARASITOLOGY

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2014 vol. 199 p. 1 - 7

0304-4017

The aim of this study was to evaluate whether Neospora caninum tachyzoites (Nc-1) inoc-ulated by the conjunctival route in pregnant cows were able to generate infection in theirfetuses. Group 1 contained 2 naturally infected cows; group 2 contained two cows inoc-ulated intravenously with 2.5 × 108tachyzoites, group 3 contained two cows inoculatedwith 2.5 × 108tachyzoites by the conjunctival route, and group 4 contained two uninfectedcontrol cows. The four inoculated cows from groups 2 and 3 were challenged at 23 weeks ofgestation. An indirect fluorescent antibody test (IFAT), recombinant NcGRA7-based ELISA,ELISA for IgG subisotypes and Western blot analysis were assessed to characterize thehumoral immune response in dams. Sera from their fetuses were tested also using West-ern blot analysis. Routine microscopic evaluation of H&E stained fetal tissues was madeand any fetal tissues and placentas with lesions compatible with Neospora-infection wereprocessed by immunohistochemistry (IHC). DNA extraction from fresh and formalin-fixed,paraffin-embedded fetal tissues were tested by nested PCR. All dams from groups 1, 2 and 3were seropositive by IFAT, rNcGRA7-based-ELISA and Western blot. IgG1/IgG2ratios were≤1 at weeks 27 and 29 of gestation. Only fetuses from groups 1 and 2 developed N. can-inum specific antibodies by Western blot. Histopathological lesions compatible with thosecaused by N. caninum were observed in fetuses from groups 1 and 2. N. caninum cysts andtachyzoites were observed by IHC on fetal tissues from groups 1 and 2. Only fetal samplesfrom group 2 were positive by PCR. Further work is needed not only to characterize thecellular immune response but also to clarify the consequences on the dam after conjunc-tival inoculation of N. caninum tachyzoites. This study shows that N. caninum tachyzoitesinoculated by the conjunctival route were not vertically transmitted in pregnant cows.