Risk assessment and fitness of a transgenic entomopathogenic nematode

A strain of the entomopathogenic nematode, Heterorhabditis bacteriophora, w as transformed by the addition of a heat-shock protein gene (hsp70A) from t he free-living nematode Caenorhabditis elegans. Laboratory experiments with wild-type and transgenic nematodes were done at 16, 25, 30, and 37 degrees C to investigate infectivity, reproductive capacity, and survival in water . Heat-shocked transgenic nematodes tones subjected to a heat shock that is lethal to wild-type nematodes) were included in experiments to determine i f this treatment caused sublethal damage. We found no significant differenc es in the ability of wildtype, transgenic, and heat-shocked-transgenic nema todes to infect or to reproduce in last-instar Galleria mellonella larvae o r to survive at these temperatures. We compared the ability of wild-type an d transgenic nematodes to infect and kill 11 species of invertebrates, repr esenting groups known to be susceptible and nonsusceptible to wild-type nem atodes. Transformation caused no detectable change in virulence of nematode s to any test invertebrates. Transgenic and wild-type nematodes were also i njected interperitoneally into mice and transgenic nematodes were fed by in jection to mice without mouse mortality or changes in growth rate. We concl ude that genetic engineering has provided a precise method to alter the hea t shock tolerance of H. bacteriophora without affecting other important lif e history characteristics and that the transgenic nematode is unlikely to p ose any threat to the environment if released on a wide scale. (C) 1999 Aca demic Press.