Experimental infections with Campylobacter fetus subspecies venerealis in cattle (#76)
Development of effective protocols to replicate the transmission of C. fetus subsp. venerealis in cattle is critical for the evaluation of the biology of the organism as well as the host immune response. Protocols for experimental infections with C. fetus venerealis in bulls and heifers were developed. A total of 6 Brahman bulls and 11 Brahman heifers were randomly allocated to four experimental groups containing exposed and unexposed animals. One group of bulls and one group of heifers were challenged by experimental exposure by intrapreputial and intracervical inoculation with a C. fetus venerealis suspension respectively. The remaining groups were challenged by natural mating with previously infected animals. Detection of C. fetus venerealis using culture and real-time PCR in smegma samples from bulls and cervico-vaginal samples from heifers; and macro and histological examination of tissue samples from the reproductive tracts collected after slaughter were performed. C. fetus venerealis was detected by culture and/or real time PCR in all groups post-challenge. Experimental exposure was more effective in establishing infection in bulls and heifers and the infectious status appeared to last longer (up to 10 weeks in bulls and 7 weeks in heifers). There was minimal cellular inflammatory response after experimental and natural challenge.