Development and evaluation of a nested PCR based on spherical body protein 2 gene for the diagnosis of Babesia bovis infection.

We developed and evaluated a nested PCR assay for the diagnosis of Babesia bovis infection in cattle based on the spherical body protein 2 gene (SBP2) from B. bovis. The specificity and sensitivity of the test were compared with the B. bovis RAP-1 gene nPCR. The SBP2 primers have specificities of 100% for B. bovis DNA. The sensitivity of the SBP2 nPCR to B. bovis from the in vitro cultured parasites was higher than that of the B. bovis RAP-1 gene nPCR, and a parasitemia as low as 10(-8)% was detected. The sensitivity of the SBP2 nPCR to B. bovis-diluted genomic DNA was also higher than that of B. bovis RAP-1 gene nPCR, and as little as 1fg per test detected. For field applications, the sensitivity to a total of 145 field samples from Ghana, Mongolia, and Brazil was evaluated. The nPCR assay of spherical body protein-2 gene detected 87.6% (127/145), while B. bovis RAP-1 gene nPCR detected 37.2% (51/145) of the total samples examined. This nPCR assay provides a good diagnostic tool for the laboratory diagnostic assessment of B. bovis infection in cattle worldwide.