Abstract: The present invention provides a vaccine composition including a nucleic acid that encodes an amoeba-derived antigen (or a peptide molecule encoded thereby), or fragments or variants thereof. The present invention also provides for the use of such vaccine compositions in eliciting an immune response and/or protective immunity in a host against amoebic infection and screening a sample for the presence of amoebae.

Abstract: A biological activity probe for the detection on-line of the presence of sulphide including an enzyme electrode; a counter electrode; a reference electrode; and if desired a corrosion electrode. The enzyme electrode includes an immobilised source of sulfide oxidase enzyme, together with a cofactor such as 1,1′-dimethylferrocene, immobilised in a water permeable non-conducting binder on a biologically inert electrically conducting substrate. The immobilised source of sulfide oxidase enzyme is either a chemoautotropic microorganism such as a Thiobacillus thioparus, or enzyme material recovered from a culture of a Thiobacillus thioparus.