Bovine Genital Campylobacteriosis is characterized by early pregnancy loss and temporary infertility in cattle. The purpose of this project was to compare diagnostic approaches to detect Campylobacter fetus subsp. venerealis and evaluate the efficacy of vaccination for Bovine Genital Campylobacteriosis. This thesis describes the results of two studies that compared different sample preparation methods for bovine vaginal mucus for real-time PCR and assessed a commercial vaccine in preventing infection and reproductive loss.
The first study compared real-time PCR utilizing different bovine vaginal mucus sample preparation techniques to direct culture. The magnetic bead based protocol demonstrated higher sensitivity (48.4%, P=0.02) and lower specificity (78.9%, P=0.01) than the heat lysis protocol which involved an additional dilution step (Sens=29.4%, Spec=88.2%), but did not differ from the heat lysis protocol without sample dilution (Sens=35.0%, P=0.16; Spec=81.1%, P=0.62). The sample preparation method, designed for bovine preputial samples (Chaban et al. 2012. Can J of Vet Res; 76: 166), did not work well for vaginal mucus. All modifications of that method and magnetic bead based extraction technique had low sensitivity compared to culture probably due to the biophysical properties of vaginal mucus, which could cause loss of targeted DNA during processing, or repeated sample freezing and thawing. Release of DNA directly from vaginal mucus by a modified heat lysis protocol with consequent real-time PCR could be a promising rapid screening approach after validating on fresh samples.
The second study compared the risk of infection and reproductive failure in heifers, vaccinated with a commercial multivalent vaccine containing C. fetus antigen, to heifers vaccinated with a comparable product without C. fetus, that were exposed to infected bulls. There was no significant difference between groups either in risk of Campylobacter fetus subsp. venerealis isolation (P>0.17) or in the proportion of heifers that cultured positive at least once (P=0.42), as well as in the median number times of cultured positive samples (P=0.24) and the time to first cultured positive (P=0.67). There was no difference by treatment in the weekly proportions of heifers diagnosed pregnant by either ultrasound (P>0.31) or serum concentration of pragnancy specific protein B (P>0.31) during the study, as well as in the time to first pregnancy for heifers ever diagnosed as pregnant (P=0.30) and those that remained pregnant at the end of the study (P=0.70). Similarly, the difference was not detected by treatment in the proportion of animals, ever detected pregnant during the study (P=0.57) and in pregnancy loss rates (P=0.28). However, heifers that aborted were 4 times more likely to be cultured positive than those that did not abort (P=0.01). Heifers that were not pregnant at the end of the study cultured positive 1.5 times more often than pregnant animals in treatment group (P=0.04), while in control group such difference was 4 times (P=0.01). Heifers that were not pregnant at the end of the study did not differ by treatment in the number of times cultured positive (P=0.14). In this study, the mean concentrations of ELISA antibodies to C. fetus after vaccination were more than 2 times higher in treatment group than in control group (P<0.02), but vaccination did not significantly reduce infection or improve pregnancy in heifers when exposed to Cfv-infected bulls.
Sample preparation technique is important for successful real-time PCR; release of DNA directly from a CVM sample by a modified heat lysis protocol was easy to perform and could be promising as a rapid screening approach for Bovine Genital Campylobacteriosis after validating on fresh samples. Vaccinating of heifers with a polyvalent commercial vaccine, containing Campylobacter fetus antigen, according to the label, did not significantly reduce infection rate or improve reproductive performance when they were naturally challenged.
| Identifer | oai:union.ndltd.org:USASK/oai:ecommons.usask.ca:10388/ETD-2015-10-2318 |
| Date | 2015 October 1900 |
| Contributors | Hendrick, Steve H. |
| Source Sets | University of Saskatchewan Library |
| Language | English |
| Detected Language | English |
| Type | text, thesis |
Page generated in 0.0017 seconds