PASTEURELLA-HAEMOLYTICA ULTRAVIOLET-IRRADIATED VACCINE BY PARENTERAL AND AEROSOL ROUTES COMPARED IN THE GOAT MODEL

Positive control 1 (PC1) (n = 9) goats were injected transthoracically into the left lung with live Pasteurella haemolytica biovar A, serova r 1 (PhA1) in polyacrylate (PA) beads on days 0 and 21. Positive contr ol 2 (PC2) (n = 6) goats were nebulized with live PhA1 and PA beads on days 0 and 21. Negative control (NC) goats (n = 6) were each injected transthoracically into the left lung with PA beads alone on days 0 an d 21. Four groups (n = 6) were administered PA beads mixed with ultrav iolet (UV) killed PhA1 on days 0 and 21. The treatment doses of bacter ia for these groups were principal group 1 (PR1) injected into the lef t lung (7.7 X 10(10) cfu); PR2, 7.7 X 10(10) UV-killed PhA1 injected s ubcutaneously (SC); PR3, 7.7 X 10(10) W-killed PhA1 injected SC only o n day 21; PR4, nebulized with PA beads mixed with 5.6 X 10(10) cfu of UV-killed PhA1; and PR5, nebulized with PA beads mixed with 5 X 10(8) cfu of UV-killed PhA1. All goats were challenged transthoracically in the right lung with 1 X 10(8) cfu of live PhA1 on day 42 and necropsie d on day 46. The sizes of consolidated lung lesions at the challenge s ite were used as a measure of immunity. The data show that the introdu ction of live PhA1 into the lungs of goats, either by injection or aer osolization, offers excellent protection against a subsequent homologo us challenge. The data also demonstrate that two transthoracic injecti ons (21 days apart) of UV-killed PhA1 (PR1), and subcutaneous injectio n of UV-killed PhA1 (PR2) also offer excellent protection against a su bsequent homologous live PhA1 challenge. One SC injection of UV-killed PhA1 (PR3) appears to offer only partial protection against a subsequ ent homologous live PhA1 challenge. Inhalation of UV-killed PhA1 mixed with PA beads (PR4 and PR5) induced no protection in goats against a subsequent live PhA1 transthoracic challenge.