The main theme of this conference was understanding the complex biology of viruses in order to design appropriate vaccines for human use. The use of both plant and animal viruses as vectors for delivery vehicles was widely discussed. These engineered viruses could be delivered in oral formulations or, in the case of plant viruses, grown in the plant host and used as edible vaccines. New technologies for producing highly attenuated vaccines through the use of 'molecular clone technologies' were shown to be highly efficacious in animal models. While new vaccine candidates are being generated against many established viral diseases, there remains a threat from HIV, virulent strains of influenza and newly emerging viruses for which no vaccines are currently available. Emerging viruses, such as the Hendra-like virus called Nipah, which emerged in pig herds in Malaysia and Singapore in 1998, has posed a severe economic threat to the region. The subsequent spread of Nipah virus to humans and the threat of epidemic spread was evidence that virologists should not become complacent.