, 2009). Similarly in this study in cattle, it is plausible that the QuilA in the vaccine may provoke an adequate immune response to viral and bacterial infection despite concurrent infection with F. hepatica. It is also noteworthy that the immunoregulatory effects described by Flynn et al. (2007) relates to the suppressive effect of F. hepatica on the type IV delayed hypersensitivity (antibody independent) reaction, as modelled on the intradermal skin test. The vaccine used in this trial has a combination of bacterial and viral antigens, which is likely to induce a different immune response to that caused by Mycobacterium bovis
and therefore may relate to the difference between immune mechanisms involved in an antibody independent Inhibitor Library clinical trial hypersensitivity reaction and an antibody dependent immune response to vaccination.
Relative to other comparable studies (Waldvogel Selleckchem Olaparib et al., 2004) where a higher dose of F. hepatica metacercariae was used, the low dose used in this study could have resulted in a parasite burden too low to have a demonstrable effect on vaccine responsiveness. However, all animals in the experimental group were infected, and did mount an immunological response to liver fluke infection as indicated by seroconversion and increased liver enzymes. Low number of calves with a positive faecal egg count reflects the fact that the analysis was conducted early in the patent Mephenoxalone period. Also, detection of F. hepatica eggs in bovine faeces is a relatively insensitive diagnostic method ( Anderson et al., 1999). The increase in eosinophils as well as liver enzymes was significantly higher in the experimental group relative to the non-infected group, where no or little increase in these parameters was identified. In contrast, neutrophil numbers, which were elevated relative to the reference range at the start of the experiment, followed by a decline in both groups, were significantly lower in the infected group relative to the non-infected group. This observation in the neutrophil count was in contrast to other studies (Egbu et al., 2013) where a
significant increase was identified. A reasonable explanation to account for this response is not forthcoming. Stress, as a cause of the initial elevated numbers, is an unlikely explanation, given the animals were on the farm for 2 months prior to the commencement of the experiment. However, it is possible that an unknown sub-clinical infection may account for the unusual neutrophil profile, with the concurrent F. hepatica infection potentially hampering the neutrophil response in the infected group. The expected cytokine profile following liver fluke infection of elevated Th2 and inhibited Th1 profiles was not identified. In contrast to previous research, we found IL-4 concentrations produced by unstimulated and stimulated PBMC to be higher in the control group.