Analysis of proteins related to conditioning for arrested development and differentiation in Haemonchus contortus by two-dimensional gel electrophoresis.

The abundance of the majority of proteins of infectious third-stage larvae (L3) of Haemonchus contortus, conditioned for arrested development, remained unaltered. Only seven proteins showed quantitative differences as observed by two-dimensional gel electrophoresis. These differences were also observed in a laboratory strain which has lost the ability for arrested development. The abundance of two of these proteins increased dramatically during conditioning of larvae for 5-10 weeks. This coincided with the highest percentage of inhibited larvae in experimental infections. Moreover, the abundance of these proteins decreased again after prolonged conditioning (22 weeks). The abundance of the other 5 proteins was not correlated to the percentage of inhibition. We therefore conclude that these proteins are involved in the aging process of larvae. The changes in protein between free-living (L3) and parasitic stages (L4) were large and seem to reflect the large environmental changes experienced by the larvae when entering a mammalian host. Early fourth- (EL4) and late fourth- (LL4) stage larvae differed in 9 proteins. One protein was stage-specific for EL4. These results imply that only minor alterations do occur in these stages notwithstanding the large morphological differences between these larvae.