Serological Studies on Leptospires with Particular Reference to Improvement of Diagnostic Techniques

Abstract

High titred antisera to three serotypes of Leptospira and Erythrocyte Sensitizing Substance (ESS) were prepared in rabbits and subjected to haemagglutination (HA), Microscopic agglutination (MA) and immunodiffusion tests. The antisera were absorbed with ESS and subjected to HA and MA tests to observe the degree of anti-ESS reactivity. The MA test with monovalent antisera gave high titres (4096 to 8192) with homologous antigens. Very low titres were recorded with polyvalent and anti-ESS antisera and when heterologous antigen were used with monovalent antisera. The MA test showed broad reactivity against each antiserum (32 to 128). Absorption of the antisera with ESS considerably reduced the titres in both HA and MA tests compared to pre-absorption titres. Fluorescein lsothiocyanate (FITC) conjugates prepared from the antisera were applied to homologous serotypes to evaluate staining capacities. Generally, the specific fluorescence obtained was unsatisfactory. In only one instance (FITC/ anti-patoc with patoc organisms) was there bright staining. The other homologous staining regimes produced only faint fluorescence and with heterologous combinations staining was very faint or non-existent. When the antisera were subjected to immunodiffusion against ESS there was precipitin line against all antisera employed except anti-patoc