Mycoplasma contamination of fish virus vaccines

When bacterial, viral or parasitic pathogens are grown in cell culture ther e is the inherent risk that slow-growing Mycoplasma sp. may become an unsee n amplified contaminant. Recently, salmonid cell cultures used to grow the intracellular bacterial pathogen, Piscirickettsia salmonis, were shown to b e contaminated with Mycoplasma. This unidentified contaminant led to an err oneous conclusion concerning the antigens of P. salmonis, with implications of misdiagnosis. Further, these results raised concern that commercial fis h viral vaccines may be similarly contaminated (Kuzyk et nl., 1999. Bull fu r. Ass. Fish. Pathol. 19(4), 142-145). Here we examine viral vaccines from two commercial sources using nested PCR primers targeted to spacer sequence s of 16S - 23S rRNA genes of Mycoplasma Mycoplasma sp. We demonstrate that three different, commercial viral vaccines against viral pathogens were ind eed contaminated with Mycoplasma. These results were confirmed by Western b lotting using antisera raised against Mycoplasma sp. The implications of th ese findings with respect to improved methodologies for Mycoplasma detectio n and their application to fish vaccines are discussed.