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 一些单独的病毒的混合,已经成功做成对抗病毒的疫苗,譬如像人类的天花,是相同的亚科病毒,是利用牛痘病毒做成的,而且人类的麻疹为小狗的大瘟热疫苗。