The studies on emerging viral diseases are restrained by a “bottle neck”: no competent animal model available． Models based on nonhuman primates have similar clinical manifestations to human diseases; however，it is uneconomic to construct such models． Furthermore，there is a controversy about protection of animal rights． Models based on rodents are often incompetent due to their low susceptibility for those viruses． This brief review focuses on the current studies on relations among nutrition，immunity and susceptibility to give insights in overcoming conundrums．