ABSTRACT
AIM:To understand the interaction between a195- kilodalton protein,P195, on the surface of Plasmodium falciparum merozoite and human erythrocyte.METHODS:P195 was expressed in eight fragments in E.coli.After being refolded,the expressed proteins were la- belled with12 5 I,and incubated with human erythrocytes.RESULTS:According to binding assay, three fragments of P195:M3,M6,M9were found to have ability to bind to human erythrocyte. M6,which is equal to amino acid( AA) sequence from384 to595,could bind to human erythro- cytes but not to trypsin treated human erythrocytes,and the binding could be eluted by low p H buffer solution. M3( AA 12 3to 30 2 ) and M9( AA 10 78to 12 51) also have the ability to bind to human erythrocytes,but the binding was not affected by trypsin treatment and low p H buffer elu- tion. CONCL USION:The binding site of M6might be a surface protein receptor of human ery- throcytes,while the binding site of M3and M9might be an intracellular componentof human ery- throcyte.
ABSTRACT
The effects of GPA, anti-GPA IgG, ?1acid glycoprotcin (?1-AGP), ovomucoid (OM) and wheat germ agglutinin (WGA) on the invasion of erythrocytes by P. falciparum were obseryed in vitro. GPA, anti-GPA IgG and WGA at low concentrations had obviously inhibitory effects on thc invasion. There were hyperbolic relationships between the concentrations of these inhibitors and their inhibition rates. OM, ?1-AGP and non-spccific anti-serum had no obvious effect on the invasion. It is confirmed for the first time from the biological characteristics of receptor-ligand interaction that thc combination of GPA with P. falciparum merozoites has high spccificity, high affinity with a tendency to sa-turation and can produce specific biological effects.
ABSTRACT
Four cell lines (C6, H6, B6, 2H6) of hybrids secreting monoclonal antibodies (McAb) against erythrocytic stage of Plasmodium falciparum Fcc7801/HN were established by fusing SP2/0 myeloma cells with spleen cells of BALB/c mice immuniaed with the preparation of the same malaria parasite and cloning three times. Of these four lines, C6 and B6 showed significant growth-inhibition of P. falciparum in vitro. Both C6 and B6 McAb recognized 71 kD antigen of P. falciparum by Western Blotting. The results indicate that the 71 kD antigen is of immune protection The four McAb showed cross immunofluorescence reactivity with P. falcipanum Fcc-1/HN, Fcc7802/HN, Fcc8703/JS and P. berghei. P. cynomolgi. It indicates that there are common epitopes among these malaria parasites, and that it is important in immunologic research and serodiagnosis of malaria
