Copy number variation of ß-defensin genes in Behçet's disease.

OBJECTIVES: Behçet's disease (BD) may be triggered by infectious agents in genetically susceptible persons. Human ß-defensin 2 is an inducible antimicrobial peptide, the level of which can be influenced by copy number (CN) of the DEFB4. We investigated the relationship between copy number variation (CNV) of DEFB4 and BD. METHODS: One hundred and ninety-seven patients with BD and 197 healthy controls were enrolled. After measuring CN of DEFB4 with a paralogue ratio test, the CNV was compared between patients and controls. CNV was also analysed in comparison with the clinical manifestations of BD. RESULTS: The CN of DEFB4 was unimodally distributed among the study subjects with mean CN of 4.57 and standard deviation of 1.28. BD samples had numerically lower CN than controls, but the difference was not statistically significant (4.49 ± 1.21 vs. 4.65 ± 1.36, p=0.245). Regarding the relationship between CN of DEFB4 and clinical manifestations, there was no difference of CNV depending on the clinical manifestations. CONCLUSIONS: We found no significant difference in CNV of DEFB4 between patients with BD and controls. Our results suggest that CNV of DEFB4 may not contribute to the pathogenesis of BD.

Characterization of the thioredoxin peroxidase from Cryptosporidium parvum.

Cryptosporidium parvum can survive exposure to harsh environmental conditions, various disinfectants, and high doses of γ-radiation. Recently, it was found that the expression of thioredoxin peroxidase (CpTPx) in C. parvum increased after a high dose of γ-irradiation to the parasite. CpTPx is a two-cysteine peroxiredoxin that contains cysteines at positions 49 and 170. Recombinant CpTPx fused to an N-terminal hexahistidine sequence, (His)(6)-CpTPx, exhibited substantial thiol-dependent peroxidase activity that protected plasmid DNA from damage by metal-catalyzed oxidation in vitro. (His)(6)-CpTPx was used to screen sera from C. parvum-infected mice and humans for antibodies against CpTPx. In Western blots, 10% of the mouse sera and 20% of the human sera reacted with (His)(6)-CpTPx, suggesting that after infection by C. parvum CpTPx can induce a host-immune reaction but is not a major antigen. Immunolocalization studies revealed that CpTPx is expressed mainly in the cytoplasm of C. parvum at various developmental stages.