ABSTRACT
Objective To conduct the amplification,cloning,bioinformatics analysis,prokaryotic expression and purification of enterovirus 71 VP1 gene segment and to initially confirm the biological activity of the recombinant expression product.Methods A pair of specific primers was designed according to GenBank EV71 sequence,viral RNA as a template was extracted from the throat swab specimens in the EV71 patients.EV71 VP1 gene was amplified by RT-PCR.After enzyme digestion,the expression vector pET28a was inserted.The prokaryotic expression vector of pET28a-EV71 VP1 was constructed.Then the E.coli DH5a transforma-tion was performed.IPTG was adopted for induction expression.The expression results were analyzed by using SDS-PAGE and Western blot.The bioinformatics analysis of the sequenced results was performed by the software.Expressed protein was purified and the plates were coated,ELISA was used to test the VP1 specific IgG antibody in serum samples of EV71 positive and COX A16-positive patients.Results The BLAST alignment showed that the homology of the objective gene EV71 VP1 was 99% com-pared with other strains(JQ766207.1)in GenBank.EV71 VP1 protein was about 32×103 ,which mainly existed in the form of in-clusion body.The bioinformatics analysis showed that EV71 VP1 protein was a hydrophilic protein,without transmembrane region and N-terminal signal peptide sequence,the tertiary structure existed.The ELISA results showed that the specific IgG OD value in EV71-positive patients was(2.425±0.521),OD value in COX A16 positive patients was(1.205 ±0.314),the normal control OD value was(0.353±0.128).The sensitivity and specificity of EV71 VP1 protein detection were 84% and 88% respectively.Conclu-sion The pET28a-EV71 VP1 expression vector is successfully constructed;the preliminary analysis on the serum of the infected patients by ELISA shows that the obtained objective protein has higher sensitivity and specificity,which is initially confirmed to have biological activity and can be further used for the related study on EV71 diagnosis and vaccine.
ABSTRACT
Objective To determine the prevalence of antibodies to cyclic citrullinated peptides (antiCCP) in patients with juvenile-onset systemic lupus erythematosus (JSLE) and its potential clinical significance. Methods Anti-CCP was measured in sera from patients with JSLE (n=47), juvenile idiopathic arthritis (JIA, n=54) and the sera from age-matched healthy children (n=40) using the third generation of anti-CCP ELISA commercial kit. The association of anti-CCP with other laboratory parameters and clinical features, especially arthritic symptoms in JSLE was also analyzed. T-test, Mann-Whitney U test, Chi-square and Fisher's exact test were used for statistical analysis. Results Out of the 47 JSLE patients, 6 (13%) were anti-CCP positive, which was significantly higher than that of the healthy controls( 13% vs 0, P＜0.05 ), but not different from that of the JIA group (26%, P=0.098). RF was more prevalent in JSLE patients with anti-CCP than patients without (83% vs 15%, P＜0.01 ), but there was no difference in other laboratory parameters and the clinical features ineluding the occurrence of arthritis (67% vs 51%, P＞0.05). As one of the initial symptoms, arthritis was observed in 25 of 47 JSLE patients and no one had developed deforming arthropathy.There was no statistical difference in anti-CCP positivity between JSLE patients with and without articular involvement ( 16% vs 9%, P＞0.05 ). Anti-CCP was not detected in any of the 3 patients with JSLE who had experienced joint pain and limited activity during 3 years follow-up. Conclusion Anti-CCP could be detected in patients with JSLE. It is noteworthy when differentiate from juvenile idiopathic arthritis, but the presence of anti-CCP does not relate with the occurrence of arthritis at presentation and persistence of arthritis in JSLE.