| 摘要 |
<p>A live vaccine for bovine babesiosis comprises viable bovine erythrocytes parasitized with a cloned population of Babesia bovis, the clone strain being fast-growing, avirulent, and producing a mild but immunizing infection when administered. The vaccine in free of slow-growing virulent B. bovis. The clone strain used in the vaccine is prepared from a natural mixture of virulent and avirulent babesia by progressive dilution culturing to obtain cultures containing single parasites, propagating the single parasites under favorable conditions for growth, and selecting a fast-growing avirulent clone line for either in vitro or in vivo propagation to prepare tha vaccines. </p> |
