viroid

例句：

1. 1. The virus has spread rapidly across the globe.
   该病毒已迅速在全球范围内传播。
2. 2. Viruses are responsible for many diseases in humans and animals.
   病毒是人类和动物许多疾病的罪魁祸首。
3. 3.Researchers have been working on developing a vaccine against this viroid.
   研究人员一直在努力研发一种针对这种病毒体的疫苗。