Scientists genetically engineered the plant in 1999 to resist the virus. Since then, they have been trying to give the technology away. But African nations, caught between the United States and Europe in a smoldering fight over biotechnology, have yet to allow field tests on their soil. [...] Nigeria was very interested in the biotech cassava at first. The Danforth Center flew Nigeria's national biosafety committee to St. Louis. But the committee postponed approval meetings. In 2004, Malawi nearly approved a field trial, but it was held up indefinitely by one official. [...] Last spring, he discovered that offspring from the cassava developed in 1999 had suddenly lost their resistance to the mosaic virus. The current cassava was engineered more cleanly, Fauquet says, and should retain its resistance.