Immunization with Neospora caninum live tachyzoites in prepubertal female calves as a novel vaccination strategy

HECKER, YANINA PAOLA; FIORANI F.; MALDONADO J.; DORSCH M.; CIRONE K.; CHEUQUEPÁN F.A.; COLQUE L.A.; CAMPERO L.M; ZAMORANO P.I.; CANTÓN G.J.; MOORE D.P.

Congreso; Apicowplexa virtual meeting, 2020; 2020

Neospora caninum is an obligate intracellular protozoan that causes abortions in cattle. More than one billion dollars annual losses are due to neosporosis in the cattle industry worldwide. No vaccines or drugs are available against this protozoan. The aim of the present study was to evaluate the safety in heifers vaccinated with live tachyzoites of N. caninum at their puberty.Seven pregnant Angus heifers inoculated before reaching puberty were involved in the present study: four animals were immunized intravenously with 1×106 live tachyzoites of NC-Argentina LP1 strain (Group A); and three animals received PBS (Group B, control). Serum, placenta and umbilical cord samples were collected from dams and their calves at delivery before calostrum intake. The presence of antibodies in dams and calves was evaluated by indirect fluorescence antibody test, indirect ELISA and Immunoblot. Parasite DNA detection was assessed by nested PCR. Serological results showed that 4/4 dams and 1/4 newborn calves from Group A were seropositive to N. caninum at birth. All dams and calves from group B remained N. caninumseronegative. In addition, N. caninum DNA was not amplified in any placenta or umbilical cord samples analyzed from both groups. Possibly, an effective protective immune response was induced in dams that received live tachyzoites limiting dissemination of N. caninum to the placenta and their progeny. Although recrudescence happened in the dams, the congenitalinfection was evidenced only in one calf. No N. caninum DNA detection by PCR was described in Group A or in the infected calf, possibly indicating low parasite load. Immunization with live N. caninum tachyzoites in prepubertal female calves could be a novel vaccination strategy. Future trials are carried out in order to determine if this immunization model is able to protect the fetuses against heterologous challenges.