Haemolytic activity associated with parasporal inclusion proteins of mosquito-specific Bacillus thuringiensis soil isolates: a comparative neutralization study.

Solubilized parasporal inclusions of the three mosquito-specific Bacillus thuringiensis isolates belonging to three different H serovars, co-isolated from a single soil microhabitat, showed haemolytic activity towards mammalian erythrocytes. Neutralization tests with antibodies against whole inclusion proteins resulted in crossed neutralization of haemolytic activity among the isolates and the type strain of B. thuringiensis serovar kyushuensis, indicating that the three soil isolates produce toxins related to the CytB toxin. No cross-neutralization occurred between the type strain of B. thuringiensis serovar israelensis and the three soil isolates.