Evaluation of the efficacy of a trivalent vaccine mixture against a triple challenge with Mycoplasma hyopneumoniae, PCV2, and PRRSV and the efficacy comparison of the respective monovalent vaccines against a single challenge

Oh, Taehwan; Park, Kee Hwan; Yang, Siyeon; Jeong, Jiwoon; Kang, Ikjae; Park, Changhoon; Chae, Chanhee

At − 14 dpc (42 days old), the pigs in the Vac3FLEX/ Ch3 and UnVac/Ch3 groups were challenged with two pathogens: PRRSV and M. hyopneumoniae. Three milliliters of the PRRSV inoculation containing 1.2 × 10 5 50% tissue culture infective dose (TCID 50 )/mL was intranasal administered (1.5 mL per nostril). Five hours later pigs were anesthetized with a mixture of 2.2 mg/ kg xylazine hydrochloride (Rompun, Bayer Korea, Seoul, Korea) and 2.2 mg/kg tiletamine hydrochloride and 2.2 mg/kg zolazepam hydrochloride (Zoletil 50, Virbac Korea, Seoul, Korea) by intramuscular injection to prepare for the M. hyopneumoniae portion of the challenge. Pigs were then inoculated intratracheally with 7 mL (3.5 mL per nostril) of M. hyopneumoniae culture medium containing 10 7 color changing units (CCU)/mL as previously described [25, 26] . This separation of challenges was done to avoid mixing of the two pathogens which could potentially affect their infectivity. Pigs in the VacPRRS/ChPRRSV and UnVac/ ChPRRSV groups were inoculated with the same lot of PRRSV and in the same way as described above, and pigs in the VacMhp/ChMhp and UnVac/ChMhp groups were inoculated with the same M. hyopneumoniae lot and in the same manner as described above.