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Acta sci. vet. (Online); 39(3): 1-6, 20110000. tab

Artigo em Inglês | VETINDEX | ID: vti-11568

Resumo

Background: The acute-phase response to infection is also characterized by an increase in protein turnover plus an increased loss of protein. Leukocyte proliferation and the synthesis of cytokines, immunoglobulins and positive acute phase proteins(APPs) contribute to protein turnover APPs levels, as markers of inflammation, usually rise significantly during the course of acute and chronic infections in the bovine. There has been a great interest shown on the usage of APPs as a marker of animal health or, alternatively, as an indicator of disease severity in veterinary medicine . Haptoglobin (Hp) and serum amyloid A (SAA) are important APPs in cattle , in different viral and bacterial infections The purpose of the present study was to investigate the influence of infection on acute-phase proteins in seldom persistent positive BVDV cattle, that were free of signs and symptoms of secondary infections. Materials, Methods & Results: Blood samples, from a total of 313 cows from three different farms, were collected in 10 mL polystyrene tubes coated with an anticoagulant (EDTA). Commercial BVDV antigen ELISA kits were used to determine the persistently infected animals. Sampling was carried out by two occasions within 40 days intervals. A total of 11 dairy cows were found BVDV Ag positive in both occasions, were evaluated as persistently infected. Eight non-infected dairy cows from same herds were served as control group. All animals were examined on the day of blood sampling. The levels of haptoglobin and SAA in serum were determined by use of the commercial kits. Statistical analyses were performed by Mann-Whitney Utest; P < 0.05 considered significant. None of the persistently infected animals showed clinical findings and a few of them were considered as poor doers, but they were unnoticed until they were identified as persistently infected animals. No clinical findings were observed in healthy control cows in routine clinical examination. Serum concentration of Hp in persistently infected cattle with BVDV was significantly (P < 0.05) higher than the controls. Serum amyloid A concentrations were also significantly higher in persistently infected cattle with BVDV than the controls. Discussion: APPs have been proposed as valuable indicators of the manifestation and severity of pathological conditions in humans and animals. Levels of APPs are preferentially elevated during acute bacterial infections and less pronounced or even missed during viral infections. There are no reports on the alterations of the acute-phase protein profile in the persistent BVDV infection. In the present study, a significant increase in the positive acute-phase proteins haptoglobin and SAA in the symptom free persistent cattles were detected. These alterations of acute-phase proteins may be associated to the enhanced production of IL-6 and IL-8 which modulate the synthesis of positive acute-phase proteins. Clinical symptoms were not noticed in our study. Such animals could easly be underdiagnosed in a farm population. Clinical symptoms were associated with increase in APPs. Moreover, supra-normal APP values in persistently infected cattle with BVDV were observed without clinical symptoms. The role of inflammation as defined by Hp and SAA levels have not been fully explored in the context of persistently infected cattle with BVDV disease. The results of this study indicated that serum concentrations of haptoglobin and SAA were increased in persistently infected cattle. Moreover, it may be suggested that measurement of SAA and Hp may be of valuable in indicating suspected persistently infected animals with BVDV in screening herds for general health status.(AU)

Biblioteca responsável: BR68.1