We will keep this policy under review as we learn more about the virus and its effects.
随着我们对这一病毒和其影响了解得更多，我们将继续审查这一政策。
2
Further research has shown that caterpillars become virtually immune to the wilt virusas the trees on which they feed respond to increasing defoliation.
进一步的研究表明，毛虫对萎蔫病毒几乎具有免疫力，因为它们赖以为生的树木会对越来越多的落叶做出反应。
3
Meanwhile, the deadliest strains of the virus perished with their hosts as natural selection favored strains that could infect hosts but not kill them.