Isolation and characterization of class II myosin genes from Haemonchus contortus.

In this study, cDNAs encoding myosin from the parasitic nematode Haemonchus contortus were isolated and characterized. Several exhibited a considerable degree of sequence variation at the nucleotide and limited divergence at the amino acid levels within the various functional domains. The results suggest that the cDNAs isolated represented a single myosin heavy chain, which, by comparison with a number of other myosins, is inferred to represent a homologue of a muscle myosin (CeMHCA) of the free-living nematode Caenorhabditis elegans. The findings could have implications for investigating cytoskeletal dynamics and/or signalling pathways.

Class II myosins in nematodes-- genetic relationships, fundamental and applied implications.

Myosins are represented by a wide range of different classes of molecule, of which the most extensively studied are the class II myosins which drive muscle contraction and cell organization; the functional unit of class II myosins comprises two myosin heavy chains (MHCs). This minireview gives an update on class II MHCs of nematodes and describes a comparative analysis of MHC genes from nematodes and other organismal groups. Genetic analyses of sequence data for the four functional domains of MHCs (i.e., the SH3-like N-terminal, head, neck and tail domains) reveal a delineation between both the nematode and non-nematode myosins and between muscle and non-muscle myosins. The distinctiveness of the MHCs of nematodes suggests functional and tissue specialization. The elucidation of the functional roles of myosins and other molecules in specific signaling pathways in nematodes has the potential to lead to new intervention strategies for parasites via the specific disruption or interruption of key developmental processes, having biotechnological implications in the longer term.

In vivo electroporation improves immune responses to DNA vaccination in sheep.

In vivo electroporation was utilised to enhance plasmid DNA expression in sheep muscle to improve the immune response to DNA vaccination. DNA encoding enhanced green fluorescence protein expressed at higher levels in sheep muscle following in vivo electroporation which caused minimal muscle damage. Groups of seven sheep were then given three intramuscular injections of plasmids encoding two Haemonchus contortus Ag, with and without electroporation at 0, 3 and 7 weeks. Humoral responses were enhanced in electroporated sheep. Four weeks after vaccination, all groups were injected subcutaneously with recombinant Ag formulated in Quil A. Induction of vaccine-specific immune memory was demonstrated in DNA-vaccinated sheep.

Characterisation of humoral immune responses in dogs vaccinated with irradiated Ancylostoma caninum.

Infection with Ancylostoma caninum, an intestinal hookworm of dogs, can cause debilitating and potentially life-threatening disease. In the current study, protective immunity to hookworm infection was induced in dogs following vaccination with irradiation-attenuated third-stage larvae (L3) with significant reductions in both worm (P<0.03) and faecal egg counts (P<0.0004) following a challenge infection. Vaccination with irradiated L3 and challenge with infective L3 stimulated a dominant antibody response to antigens of less than 20 kDa in an excretory/secretory extract from adult parasites. Immunoscreening of an adult A. caninum cDNA library with antisera from the vaccine trial identified a number of clones. The three clones with the strongest immunoreactivity proved to be identical and encoded a peptide with similarity to the N-terminal domain of the tissue matrix metalloproteinase inhibitor (TIMP)-2 mammalian tissue metalloproteinase inhibitor family.