ABSTRACT
Objective To understand the primary structure and potential antigenic epitopes of antigen Pf332(Ag332) of P.falciparum iso late FCC1/HN.Methods Based on the published Pf332 gene sequence , nine pairs of primers were designed for the PCR amplification of the Pf332 gen e fragments from genomic DNA of P.falciparum isolate FCC1/HN. The amplified gene fragments were subcloned into pMD-18T vectors and sequenced. The sequences were aligned using DNAstar software to obtain the full-length sequence of the gene Pf332. The primary structure and sequence homology of Ag332 were analyzed by SAPS, Tmpred, SingalP and Blastn programs. Three fragments, R0, R1 and R2, cor responding to nt#9595-10083, nt#10339-10767 and nt#10855-11247 of Pf332 gene were subcloned into the eukaryotic expression vector pcDNA3-S separately. The Balb/c mice were immunized with pcDNA3-S-R0, pcDNA3-S-R1 and pcDNA3- S-R2 separately, and the expressions of the recombinant proteins were detected by immunohistochemistry assay. The protective immune responses elicited by DNA I mmunization were analyzed by ELISA and parasite growth inhibition tests in vitro .Results Nine Pf332 gene fragments were specifically amplif ied, subcloned into pMD-18T vectors and sequenced. Pf332 gene of the P.falci parum isolate FCC1/HN was 16,377 bp in length, encoding a protein of 5,458 ami no acids, about 615.28kDa. The Ag332 contains 17 regions of highly degenerated Glu-rich repeats, with 30.18% Glu in total amino acids of Ag332. Ag332 of P.falciparum isolate FCC1/HN and 3D7 exhibited 94.55 % homology in amino acid residues. The results of immunohischemistry assay showed that R0, R1 and R2 were expressed in mice muscle tissue. The amount of IgG antibody of the groups immu nized with pcDNA3-S-R0, pcDNA3-S-R1 and pcDNA3-S-R2 were higher than those of blank and pcDNA3 groups (P＜0.05). The result of parasite growth inhibition test showed that the immunized sera at 1∶5 dilution of groups of pcDNA3-S-R0, pcDNA3-S-R1 and pcDNA3-S-R2 had an incomplete inhibitor y effect on P.falciparum growth. Conclusion The antigen Pf332 is an large protein containing highly degenerated Glu-rich repeats. Pf332 gene fragments, R1 and R2 encoding potent antigenic epitope repeats.
ABSTRACT
[Objective] To construct a eukaryotic expression plasmid containing a gene encoding a 41-3 kilodalton blood stage antigen (p41-3) of Plasmodiu falciparum isolate FCC1/HN, and to determine the sequence of p41-3 gene and analyze the homology of the sequences of 341-3 gene of different P. falciparum isolates. [ Methods] Two pairs of primers were designed according to the known sequence of p41-3 gene. Using PCR technique, the p41-3 gene was obtained by amplification from genomic DNA of isolate FCC1/HN. By cloning target gene into a eukaryotic expression vector, pcDNA3, a recombinant plasmid pcDNA3-p41-3 was con structed and trarsferred into E. coli DH5α. The positive clones were screened and identified by agarose gel electrophoresis, endonu clease digestion and PCR technique. The correct recombinant plasmid pcDNA3-p41-3 was used as template, and the nucleotide se quence of p41-3 gene was determined by the dideoxy chain termination method. Using softwares to analyze the structure and sequence homology of p41-3 gene between isolate FCC1/HN and FCBR. [Results] The p41-3 gene was specifically amplified from genomic DNA of Plasmodiumm falciparum isolate FCC1/HN, and the correct recombinant plasmid pcDNA3-p41-3 was screened and identi fied. The result of sequence determination showed that the p41-3 gene of isolate FCC1/HN was 2 137 base pairs in full length, encod ing 375 amino acids. Isolate FCC1/HN and isolate FCBR exhibited 98.98 % homology in the nucleiotide sequences and 99.73 % ho mology in the encoded anino acids of p41-3 gene. [Conclusion] The eukaryotic expression plasmid pcDNA3-p41-3 is successfully con structed and nucleotide sequence of p41-3 gene of isolate FCC1/HN is determined. The p41-3 genes of isolate FCC1/HN and isolate FCBR share quite high homology.
ABSTRACT
Objective] To determine the nucleotide sequence of the 3′\|termal of the RESA gene Plasmodium falciparum isolate FCC1/HN, and find out the differences of the sequences of RESA gene among isolate FCC1/HN,FC27,NF7 and Palo Alto. [Methods] 3′\|terminal fragment of RESA gene of P.falciparum isolate FCC1/HN was amplified by PCR method, then was cloned into pMD18\|T vector. The recombinant was screened and identified by BamHI+XhoI and PCR technique. The nucleotide sequence of the 3′\|terminal of the RESA gene was determined by the dideoxy chain termination method. DNASTAR and BLAST software were used to compare and analyze the RESA gene sequences among the different isolates. [Results] The 3′\|termal fragment of the RESA gene with about 846 bp was specifically amplified by PCR, the recombinant pMD18\|T\|RESA was successfully constructed. Different degrees of diversity of the RESA gene sequences were found among P.falciparum isolates FCC1/HN、FC27,NF7 and Palo Alto. [Conclusion] There were differences in the sequences of RESA gene among the P.falciparum isolate FCC1/HN and three other isolates (FC27,NF7 and Palto alto).