Immunomodulatory effect of Mycoplasma bovis in experimentally infected calves

Abstract

The effect of three different field isolates of Mycoplasma bovis on selected immunological parameters in experimentally infected calves was studied. Calves were kept separately in 4 experimental groups, and animals of 3 groups were infected intratracheally with one of the three selected isolates of M. bovis. The control group was inoculated intra-tracheally with sterile physiological saline. Nasal swabs and blood samples were collected just before the calf inoculation, then daily for seven days, and then weekly for another three weeks. The presence of M. bovis antigen, M. bovis antibodies, total protein, gamma globulins, IgA, IgM, IgG, acute phase proteins (haptoglobulin and serum amyloid A), as well as interferon-γ and interleukin-4 concentrations were determined. M. bovis was detected intermittently during the study in the infected groups from day 1, whilst the control group remained free of the pathogen. M. bovis antibodies were detected in some of infected animals in the second, third, and fourth week after infection. The stimulation and/or immunological suppression varied between the M. bovis isolates used for the inoculation. All M. bovis isolates induced a rise of APP and gamma globulin concentrations in infected calves. However, in this study the mucosal immune response appeared to be down-regulated, which was expressed with a general lack of IgA stimulation.

Flow cytometry follow-up analysis of peripheral blood leukocyte subpopulations in calves experimentally infected with field isolates of Mycoplasma bovis

“…In Groups E2 and E3, there was a lack of a distinct B-cell response, although the response was more marked for the E2 calf pneumonia isolate where increases in the WC4 + percentage were observed on days 14 and 28. In this study, the course of the B-cell response could be associated with the production of specific antibodies to M. bovis which were detected in our previous study in the experimental calves from day 21 for Group E2 and from day 14 for Group E3 (Dudek et al, 2013). In contrast, the WC4 + count increase was generally stimulated in the calves inoculated with the E1 mastitic isolate and specific antibodies to M. bovis were detected from day 21.…”

“…Previously Dudek et al (2013) used a similar experimental design which demonstrated the immunomodulatory effect of M. bovis in calves. In response to that M. bovis infection both a stimulation and a suppression of immunity in the affected calves was observed, depending on the mycoplasma isolate used.…”

“…It has been reported that M. bovis can have both a stimulating and a suppressing effect on host immunity (Dudek et al, 2013). It stimulates activation of the acute phase response (APR) in infected calves as a consequence of a significant increase in the specific acute phase proteins (APPs) (Dudek et al, 2010(Dudek et al, , 2011a(Dudek et al, , 2013, proinflammatory cytokine production (Jungi et al, 1996), and activates the arachidonic acid cascade (Dudek et al, 2011b).…”

“…It stimulates activation of the acute phase response (APR) in infected calves as a consequence of a significant increase in the specific acute phase proteins (APPs) (Dudek et al, 2010(Dudek et al, , 2011a(Dudek et al, , 2013, proinflammatory cytokine production (Jungi et al, 1996), and activates the arachidonic acid cascade (Dudek et al, 2011b). In contrast, it has a modulating effect on different immune leukocyte functions including the production of reactive oxygen species (ROS), but this may vary with each mycoplasma isolate.…”

“…The effectiveness of calf inoculation using these M. bovis field isolates with clinical and microbiological examinations was described by Dudek et al (2013). During the experimental study no clinical changes such as elevated rectal temperature (fever) and respiratory changes were reported in the control group.…”