Author(s): Snipes KP, Hirsh DC
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Abstract Two strains of Pasteurella multocida, both derivatives of strain P1059, were compared for virulence for 14-week-old turkeys and sensitivity to turkey plasma. Strain P1059-1, a nalidixic-acid-resistant mutant of P1059 with an LD50 of approximately 10(3) colony-forming units (CFU), was more resistant to the bactericidal effects of fresh turkey plasma at 37 C than avirulent strain P1059-1A. P1059-1A, with an LD50 of approximately 10(8) CFU, is an acapsular variant of P1059-1 that spontaneously arose after prolonged passage on artificial medium. The bactericidal effect on P1059-1A was removed when turkey plasma was treated with heat or with zymosan, maneuvers that removed hemolytic complement activity from turkey plasma.
This article was published in Avian Dis
and referenced in Journal of Vaccines & Vaccination