Wherefore , protective vaccines based on cross - reactive regions of aids viruses can provide broad immunity , and may be useful against viruses that are currently evolving in a new host , such as hiv infection of humans , yamamoto said 一些單獨的病毒的混合,已經成功做成對抗病毒的疫苗,譬如像人類的天花,是相同的亞科病毒,是利用牛痘病毒做成的,而且人類的麻疹為小狗的大瘟熱疫苗。