Temperature is a cue for gene expression in the post-infective L3 of the parasitic nematode Brugia pahangi.

The temporal expression pattern of two genes, Bp-cdd and Bp-S3, was studied at defined points throughout the life cycle of Brugia pahangi. Both mRNAs were up-regulated to coincide with the transition of the L3 from the vector to the mammalian host. Bp-cdd was expressed almost exclusively in the post-infective (p.i.) L3 and L4 stages of the life cycle while Bp-S3 was also expressed in adult worms, but at a much lower level than in the larval stages. Immunogold labelling with an antiserum raised to the recombinant Bp-CDD localised the native antigen to the hypodermis in the p.i. L3 and L4. Specific labelling was not detected in the adult worm. The expression of both mRNAs could be triggered by exposure of the vector-derived L3 to a simple mammalian culture system. Analysis of the factors, which induced expression suggested that the temperature shift which accompanies the transition from mosquito to mammal was the most important cue for expression of both genes.