O antigen

例句：

1. 1.O antigen is a common type of bacteria found in the human body.
   O抗原是一种常见的细菌，存在于人体中。
2. 2. The study of O antigens has led to important discoveries in vaccine development.
   研究O抗原的研究在疫苗开发中起到了重要作用。
3. 3. O antigen testing is used to identify infections caused by certain viruses.
   O抗原检测用于识别由特定病毒引起的感染。