Identification of a linear B-cell epitope on the avian leukosis virus P27 protein using monoclonal antibodies

Avian leukosis virus (ALV) is an avian oncogenic retrovirus that can induce various clinical tumors. The capsid protein P27 is the group-specific antigen of ALV and has many viral antigen sites that are easy to detect. In this study, we produced a monoclonal antibody (mAb), 3A9, that is specific for the P27 protein. A series of partially overlapping peptides were screened to define (181)PPSAR(185) as the minimal linear epitope recognized by mAb 3A9. The identified epitope could be recognized by chicken anti-ALV and mouse anti-ALV P27 sera. The epitope was highly conserved among a number of ALV-A, ALV-B and ALV-J strains. MAb 3A9 might be a valuable tool for the development of new immunodiagnostic approaches for ALV, and the defined linear epitope might help further our understanding of the antigenic structure of the P27 protein.

Expression and correlations of S-phase kinase associated protein 2 and P27 protein in pancreatic cancer tissues: an analyses of 51 cases

AIM: To detect the expression of S-phase kinase associated protein 2 (SKP2) and P27 protein in human pancreatic ductal carcinoma and chronic pancreatitis, and to investigate the clinical significance and their correlations in the pancreatic ductal carcinoma.

METHODS: SP immunohistochemical method was used to detect the expression of SKP2 and P27 in the routinely paraffin-embedded sections of specimens from patients with pancreatic ductal carcinoma (n = 51) and chronic pancreatitis (n = 10)..

RESULTS: The positive rate of SKP2 expression in the pancreatic ductal carcinoma (28/51, 54.9%) was significantly higher than that in the chronic pancreatitis (2/10, 20.0%, P < 0.05), while the rate of P27 was significantly lower [25/51(49.0%) vs 9/10(90.0%), P < 0.05]. The positive rates of SKP2 expression was significantly lower in the well-differentiated (7/20, 35.0%) and non-metastasis cases (5/16, 31.2%) than those in the poorly-differentiated (14/19, 73.7%) and metastasis ones (23/35, 65.7%) (P < 0.05), while the rate of P27 expression was significantly higher in the well-differentiated (13/20, 65.0%) and non-metastasis cases (12/16, 75.0%) than those in the poorly-differentiated (6/19, 31.5%) and metastasis ones (13/35, 37.1%) (P < 0.05 or P < 0.01). The expression of SKP2 and P27 were closely correlated in the pancreatic ductal carcinoma tissue (χ² = 14.33, P < 0.01)..

CONCLUSION: SKP2 and P27 are important biological markers for reflecting the carcinogenesis, progression, and prognosis of pancreatic ductal carcinoma. The positive expression of SKP2 or the negative expression of P27 reveals more serious status of the illness, the tendency of metastasis and unfavorable prognosis. There may be a co-regulatory relationship between SKP2 and P27 expression.