Studies on the characterization of the Babesia bovis monoclonal antibody PB/5 and the presence of a carboxylesterase in a Boophilus microplus tick cell line

The effect of the monoclonal antibody PB/5 was evaluated for its effect on Babesia bovis growth in vitro to determine the potential protectiveness that the 152 KDa B. bovis antigen may confer. Increasing concentrations of PB/5 up to 1 mg/ml were used and no inhibition of parasite growth was observed. The lack of inhibition could be attributed to the fact that PB/5 may recognize an internal epitope that is not accessible or PB/5 may not be accessible to B. bovis infected cell in the cell culture system.; The location of the antigen that PB/5 identifies was evaluated by confocal microscopy by a double labeling indirect fluorescent antibody test (IFAT). PB/5 was found to react with the apical site of the parasite in fixed infected erythrocytes but did not react with live infected cells. Moreover, B. bovis positive bovine serum was shown to react with the surface and cytoplasm of the erythrocyte and the parasite in fixed infected erythrocytes and with the surface of live infected erythrocytes.; The presence of a gene of carboxylesterase was determined by polymerase chain reaction (PCR) on a Boophilus microplus tick cell line. Oligonucleotide primers were designed from the nucleotide sequence of a B. microplus carboxylesterase previously described. Amplification of a fragment of 150 by from cDNA of B. microplus tick cells was found to be identical to a carboxylesterase gene fragment described previously. Also, carboxylesterase was found to be expressed in B. microplus cultured cells by Western blot with a anti-peptide polyclonal antiserum that recognized a specific protein band of 29 KDa.