Abstract: The present disclosure provides an N protein epitope mutation marker for preparing an epitope deletion-marked vaccine strain of type II porcine reproductive and respiratory syndrome virus (PRRSV) and use thereof, belonging to the technical field of biological products. In the mutation marker, one or more amino acids are mutated based on an epitope sequence at positions 92 to 103 of a C-terminal of an N protein of the type II PRRSV; and the epitope mutation marker has an amino acid sequence shown in SEQ ID NO: 1, where X1 is selected from the group consisting of T, P, and A; and X2 is selected from the group consisting of V and A.

Abstract: The present invention discloses an application of an exosome-related microRNA in preparing a marker or diagnosis and prediction of lung cancer and a kit, and develops a PCR platform-based two-step detection kit for miRNA, which has the outstanding advantage in the aspect of auxiliary diagnosis of lung cancer by the combined use of up-regulated and down-regulated molecular markers, and has the sensitivity as low as lcopy/?L, greatly improving the detection accuracy. In addition, the isothermal amplification-based one-step detection system for miRNA developed by the present invention is faster and more convenient, which can greatly improve detection efficiency and reduce detection costs.