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Canine C-reactive protein is a major acute phase protein in dogs that plays an important role in initiation and regulation of inflammatory processes. It is produced in hepatocytes after interleukin stimulus and is released in the circulation where it can be detected in serum within 4 hours after initiation of the inflammatory process.
Human medicine routinely uses CRP as a diagnostic measure and it has potential for the use in veterinary clinical practice as a biomarker for monitoring health status and response to therapy. Therefore, one objective of the study was to evaluate three different point-of-care (POC) systems for the measurement of cCRP. However, to establish its diagnostic possibilities, many details about the parameter cCRP still need to be elucidated. Another objective of this study was to increase knowledge about cCRP, with a focus on structural details and use within the clinical setting. Measuring of cCRP may be particularly useful for application in emergency medicine, as it can help determine if the underlying problem is caused by an inflammatory process. In addition, it may be used in conjunction with other diagnostic measures to help determine how severe the health condition is. Point-of-care testing devices can be used to provide rapid measurement of cCRP, however testing and evaluation of their performance is necessary due to the current lack of data regarding their applicability in veterinary clinical practice.
For the first part of the study, three different quantitative POC (TECO©dogCRP-quant, EUROLyser solo cCRP, LifeAssays® canine CRP) systems for measuring the cCRPconcentration in serum samples of dogs presented to the Small Animal Clinic, Freie Universität Berlin were evaluated. All assays were tested for their clinical applicability and precision was compared to the gold standard (ELISA). Results revealed distinct variations in their accuracy as well as reproducibility of values (TETECOmedical 69%, TEEUROLyser 28,2%, TELifeAssays 30,3%). However, all POC systems provide potential for their clinical usage not only in one-point measuring but also to monitor patients.
For disease-monitoring, it is important to measure all parameters with the same POC system, because the measured cCRP-concentration varies between the assays as well as between assay and reference method. The anti-cCRP-antibody used in the TECOmedical device was also used in the majority of immunological analyses performed, to examine its’ quality and specificity. It was found that CRP could be detected by the antibody in different species from the Caniformia family while it was not detected in unrelated species but also reacts with some bacterial proteins, which are not specified yet.
In the second part of the study, further information about the cCRP was determined. Specifically, in silico data about mRNA and amino acid (aa) sequence of cCRP were confirmed by biochemical analysis and new structural properties were characterized.
The primary amino acid sequence was found to be shorter in the serum cCRP (204 aa) than the mRNA codes for cCRP (223 aa). This might have an influence on cCRP release from hepatocytes as well as protein activation. Furthermore, the specific glycosylated protein modifications were analyzed and revealed similar structure to human CRP.
The importance of and immunological similarity with CRP in other species was examined in the third part of the study. CRP-protein could be detected in serum samples of different Caniformia species by the anti-cCRP-antibody, but failed to be detected in several species of the Eutheria family. However, the detection of CRP in the serum of dog-related species might increase the diagnostic possibilities for wild animals from the Caniformia family.