Association between haptoglobin and IgM levels and the clinical progression of caseous lymphadenitis in sheep

Abstract

BackgroundSheep caseous lymphadenitis (CLA), caused by Corynebacterium pseudotuberculosis (Cp), is associated with direct economic losses and presents significant zoonotic potential. Despite the importance of the disease, a satisfactory vaccine model has not been developed. Thus, this study aimed to investigate the association between haptoglobin (Hp) and IgM levels and the clinical progression of CLA in primarily infected sheep and in sheep immunized with Cp- secreted antigens adjuvanted with Quillaja saponaria saponins. These animals were kept with CLA-positive sheep to simulate natural exposure that occurs in field conditions. During the experiment, the Hp and IgM levels were monitored for 21 days, and the development of internal CLA lesions was investigated through necropsies on day182 post-immunization.ResultsPrimarily infected sheep in Group 2 (inoculated with 2x105 Cp virulent strain) had higher Hp values between the first and ninth days post inoculation (PI) than sheep in Group 1 (control; P < 0.05). Immunized animals in Group 3 had significantly higher Hp values between the third and seventh days PI, compared with the control group (P < 0.01). Binary logistic regression (BLR) analysis of primarily infected sheep indicated an association between Hp concentration and CLA clinical progression: animals with high Hp values had 99.9% less risk of having CLA abscesses than animals with low Hp levels (Odds ratio = 0.001, P < 0.05). Both experimental groups had significantly higher IgM titers than the control group around the ninth and eleventh days PI (P < 0.05). The BLR analysis for immunized sheep indicated an association between IgM levels and clinical progression: sheep with high IgM titers had 100.0% less risk of having CLA abscesses than animals with low IgM levels (Odds ratio = 0.000, P < 0.05).ConclusionsResistance to C. pseudotuberculosis infection is supported by the early acute phase response, in which up-regulation of Hp and IgM were predictive of a lower risk of CLA lesion development. Because the immunogen used in this study induced a high production of both Hp and IgM, Q. saponaria saponin should be considered a promising candidate in vaccine formulations against sheep CLA.

Humoral and cellular immune responses in mice against secreted and somatic antigens from a Corynebacterium pseudotuberculosis attenuated strain: Immune response against a C. pseudotuberculosis strain

“…Despite the economic [1, 2] and zoonotic [3] relevance of CL, a satisfactory vaccine model has not been developed [4, 5]. …”

Refining a ‘toolkit’ for objective assessment of pain and stress in ruminants

“…This was also observed in a study by Bastos et al (2013) that found lambs that were immunised against caseous lymphadenitis had an increase in Hp between the first day till day eleven of immunisation. Although there was a treatment effect of the surgical castration observed in the present study, the non-significant elevation of Hp in the control animals may have been contributed by the vaccination.…”

Assessment of the acid phosphatase CP01850 from Corynebacterium pseudotuberculosis in DNA and subunit vaccine formulations against caseous lymphadenitis

“…Further studies are already being carried out to evaluate the effectiveness of other adjuvants in association with rCP01850. Saponin seems to be a promising adjuvant for recombinant CLA vaccines for its ability to stimulate Th1 and cytotoxic T lymphocytes responses (Bastos et al, 2013). Silva et al (2014) obtained protection levels of up to 90 % with a formulation containing rCP40 antigen from C. pseudotuberculosis associated to saponin.…”