Humoral immunity conferred by four recombinant proteins of Neospora caninum adjuvanted with liposomes and CpG-ODN in cattle

NOVOA, MARÍA B.; SARLI, MACARENA; REIDEL, IVANA; VEAUTE, CAROLINA; PRIMO, MARÍA E.; ECHAIDE, IGNACIO E.

Mar del Plata

Congreso; Reunión Conjunta de Sociedades de Biociencias; 2019

Sociedades de Biociencias

The apicomplexan protozoan Neospora caninum is a major cause of abortion in cattle with the consequent severe economic losses to production. It persists for life in tissue cysts with periodic reactivations. The present study was designed to evaluate the immunity generated by the recombinant proteins NcMIC1, NcMIC3 (micronemes), NcSRS2 (tachyzoites surface) and NcGRA7 (dense granules), adjuvanted with liposomes (Lip) and CpG oligodeoxynucleotides (CpG-ODN) against N. caninum infection and persistence. Recombinant His-tagged proteins expressed in Escherichia coli were purified by Ni-NTA affinity chromatography. Eighteen 3-year-old steers were divided in three groups (G) of six steers each. GA animals were inoculated with 100 µg of each recombinant protein and Lip+CpG-ODN. GB received Lip+CpG-ODN adjuvant without antigen and GC received sterile phosphate buffered saline (PBS). Steers were inoculated twice (day 0 and 21) and were challenged with 1.107 tachyzoites of NC-1 strain at day 56 after the first dose (afd). Serum samples were collected weekly until day 102 afd. Indirect ELISA (iELISA) based on the four recombinant proteins (iELISAr) or N. caninum tachyzoites lysate (iELISAtach) were used to measure specific antibodies induced by the proteins. An increase in the level of antibodies against the four proteins were detected by iELISAr at day at day 14 afd and after challenge at day 75 afd in steers from GA compared with those from GB and GC (P< 0,001). The iELISAtach detected antibodies against N. caninum 12 days after challenge. The antibody titer was higher in steers from GA than in steers from GB and GC (P< 0,001). In conclusion, NcMIC1, NcMIC3, NcSRS2 and NcGRA7 recombinant proteins were immunogenic. The presence of tissue cyst in the brain of all cattle after slaughter is under analyzes.