Abstract:

In order to explore the sequence characteristics of Rhipicephalus microplus P0 gene, predict the physical and chemical properties, and secondary and tertiary structures of P0 protein, and screen the B and T dominant epitopes of P0 protein, the P0 gene of R. microplus was cloned and analyzed by Clustal X software. The physical and chemical properties, secondary and tertiary structures of P0 protein were predicted by online software EXPASY, PRABI and SWISS-MODEL, and the B and T dominant epitopes of P0 protein were screened by online software ABCpred Prediction, Scratch, IEDB and NetCTL. The results showed that the P0 gene of R. microplus was 957 bp in length, with 24.0% A, 20.3% T, 27.5% G, 28.2% C, 44.3% A+T and 55.7% G+C, encoding 318 amino acids; The molecular weight of P0 protein was 34 ku, the theoretical isoelectric point (pI) was 5.86, the average hydrophilicity coefficient was -0.153, and the instability index was 38.15; The secondary structure of P0 protein contained 163 α-helices (51.25%), 130 random coils (40.88%) and 25 extended strands (7.86%), and the α-helix was the main structure; The content of α-helix in tertiary structure of P0 protein was the highest. The value of global model quality estimation (GMQE) and qualitative model energy analysis (QMEAN) of P0 protein were 0.49 and 0.52 ± 0.05, respectively. There was no signal peptide and transmembrane domain, but there were 40 phosphorylation sites and 1 glycosylation site; There were 13 B lymphocyte dominant antigen epitopes and 6 T lymphocyte dominant antigen epitopes in P0 protein. In conclusion, the P0 gene sequence of R. microplus showed GC preference, and the P0 protein was a hydrophilic acidic protein with α-helix as the main structural component, and had the dominant antigen epitopes of B and T lymphocytes, which was an ideal target for the development of R. microplus vaccine in the future.

Key words: Rhipicephalus microplus, P0 gene, P0 protein, antigen epitope