Diagnóstico biomolecular e níveis séricos da β2- microglobulina em bovinos, naturalmente infectados pelo vírus da leucose bovina

Abstract

The enzootic bovine leukosis has economic importance, because it is the cause of death or predisposition to secondary infections, production losses, carcass condemnation, marketing restrictions on the animals or their products and reproductive performance failure. These aspects are the reason studies looking for identify cattle infected bovine leukosis virus (BLV) and the elucidation of the pathogenic action of the immune system to intensify, through the use of new diagnostic techniques. Thus, the aim of this work is to compare the AGID and PCR techniques in the diagnosis of cattle naturally infected with BLV and evaluate the usefulness of serum concentration of β2-microglobulin (β2-M) as a diagnostic feature of the evolution of BLV infection. The results of the 301 samples analyzed by AGID and PCR, 234 (77.7%) were similar and the kappa was considered as acceptable. PCR showed a sensibility of 89.5%, specificity 76.0%, positive predictive value 35.1% and negative predictive value 98.0%. The concentration of β2 -M in the 60 analyzed samples was higher in the group of calves than in seronegative individuals seropositive for the BLV, however, significant difference was not recorded. The correlation result from 60 samples of total leukocytes and β2-M in the seropositive individuals was 0.078 (p = 0.681) and 0.042 (p = 0.826) in the negative group. The values to the amount of lymphocyte/mm3 with β2 -M was 0.200 (p = 0.289) in seropositive and 0.172 (p = 0.363) in the seronegative group. Therefore, the correlations were low and not significant. From the results obtained from the correlation between β2-M, total leukocytes and lymphocytes in cattle infected with BLV can be inferred in this study that the correlation was not efficient to be used as a resource for early diagnosis of BLV infection. It was also conclude that PCR using primers from the long terminal region of the virus was effective in detecting cattle infected with BLV, suggesting that it is using as a confirmatory test, because the negative predictive value was high.