Evaluation of the counterimmunoelectrophoresis reaction as a serodiagnosis test for swine leptospirosis

The Counterimmunoelectrophoresis reaction (CIE) was tested as a genus specific test for swine leptospirosis diagnosis using three soluble extracts obtained from Leptospira sp, serovars pomona, icterohaemorrhagiae and patoc. The extracts were treated with hot Triton X-100 and applied to serum samples of animals divided in three groups: Group 1, 10 swines experimentally infected with the Pomona strain; Group 2, 50 naturally infected swines and Group 3, 10 swines control. These animals were serologically evaluated by CIE and by the Microscopic Agglutination Test (MAT), the WHO reference technique. Groups 1 and 3 were monitored during a period of 93 days after infection (a.i.). Group 1 serum convertion took place around the 10th day a.i. by MAT but ocurred earlier by CIE using any antigen. When CIE was carried out with the homologous antigen to the experimental infection, the results were consistent with MAT, but not when the heterologous antigens were used. Groups 1 and 3 showed distinct results: in Group 3, diferences between results of CIE accomplished with any three antigen extracts were not significant, indicating lack of dependence on the serovar responsible for the outbreak. Although being safe, fast, easy to perform, inexpensive and ideal for analysis of large number of samples, CIE revealed limited genus specificity, which is not convenient for field screening tests. The advantage of CIE is the capability to detect antibodies earlier than MAT. Avaliou-se a reação de contraimunoeletroforese (CIE) como teste gênero-específico para diagnóstico da leptospirose suína, usando-se três extratos solúveis de Leptospira sp, sorovares pomona, icterohaemorrhagiae e patoc, obtidos pelo tratamento com Triton X-100 a quente e aplicados a amostras de soro de suínos subdivididos em três grupos: Grupo 1, 10 suínos experimentalmente infectados com estirpe Pomona; Grupo 2, 50 suínos naturalmente infectados e Grupo 3, controle. As amostras de soros foram submetidas à reação de CIE e os resultados comparados aos da Soroaglutinação Microscópica (SAM), técnica de referência pela WHO. Os Grupos 1 e 3 foram monitorados por 93 dias após a inoculação (p.i.). Pela SAM a soroconversão do Grupo 1 ocorreu por volta do 10º dia p.i., enquanto pela CIE, empregando-se qualquer extrato antigênico, foi anterior à SAM. Quando a CIE foi realizada frente a antigeno homólogo à infecção, seus resultados foram equivalentes aos da SAM, não se verificando o mesmo frente aos antígenos heterólogos.