Conventional vaccine preparations against HPAI H5N1 are produced by propagating virus in embryonated chicken eggs or mammalian cells. The vaccine viruses used are either reassortants or low pathogenic wild-type avian viruses. Either way, the viruses need to be selected for their ability to multiply in eggs or cultured cells, which may preclude the best genetic match to the circulating HPAI H5N1 strains. In addition, these vaccines have several other limitations as reviewed elsewhere [5, 6] . Hence, other vaccine strategies against HPAI H5N1 have been explored including the use of, among others, live attenuated influenza vaccines [7, 8] , live vaccines based on heterologous viral vectors such as pox virus [9] , adenovirus [10] , baculovirus [11] and Newcastle disease virus [12] , and DNA vaccination [13] . While these different strategies often showed promising results, their applicability ultimately will depend on various important issues including safety, efficacy, production and costs [5] .