Extrachromosomal nucleic acids in bovine babesia

Two kinds of small extrachromosomal nucleic acid elements were found in the bovine babesias, Babesia bovis and B. bigemina. One element with an apparent size of 5.5 kilobase pairs (kbp) is a double stranded RNA related to virus like particles. Another molecule is a double stranded DNA with a molecular size of about 6.2 kbp. Southern blot comparison of restriction DNA fragments of the latter molecule, which is present in both B. bovis and B. bigemina is described.