Genotypic diversity in field isolates of Babesia bovis from cattle with babesiosis after vaccination.

摘要

Two polymerase chain reaction assays (Bv80 and BvVA1) were applied to analyse DNA extracts of B. bovis vaccine (K, T and Dixie strains) and 27 field isolates from 24 properties in Queensland, Australia, where disease outbreaks had occurred despite the use of the vaccine. To evaluate the stability of the genotypes identified, 11 of the field isolates were inoculated into experimental cattle that had either been previously vaccinated with T strain or not vaccinated. No particular genotype of B. boviswas responsible for the problems observed in previously vaccinated herds. None of the isolates had genotypes identical to the vaccine strains used. No geographic trends among the genotypes were observed. Isolates that originated from the same property also had different genotypes. Blood passage of the 11 field isolates in either previously vaccinated or non-vaccinated cattle did not alter the original genotype. It is concluded that no particular genotypes identified by the polymerase chain reaction assays could be associated with vaccine failures.