RESUMEN
B13, one of the immunodominant antigens of Trypanosoma cruzi, is composed of repeats of a 12-amino-acid motif. Using synthetic peptides, the sequence FGQAAAGDK was previously shown to contain the B13 immunodominant epitope recognized by chagasic patients sera. To investigate the effects of neighboring sequences in the immunodominance, we tested serum recognition of two B13 sequences fused to LamB. GDKPSPFGQAAA-LamB and FGQAAAGDKPSP-LamB were recognized, respectively, by 15% and 80% of 80 sera reactive to B13 antigen. Recognition of FGQAAAGDKPSP-LamB was inhibited by AAAGDK-containing synthetic peptides. FGQAAAGDKPSP-LamB competed with a B13 recombinant protein containing 16.6 repeats for binding to chagasic antibodies. These results strengthen previous conclusions on the immunodominant epitope of B13 and provide a comparison of two methods for epitope mapping.
Asunto(s)
Antígenos de Protozoos/inmunología , Mapeo Epitopo , Proteínas de Escherichia coli/inmunología , Proteínas Recombinantes de Fusión/inmunología , Secuencias Repetitivas de Ácidos Nucleicos/inmunología , Trypanosoma cruzi/inmunología , Secuencia de Aminoácidos , Animales , Anticuerpos Antiprotozoarios/sangre , Antígenos de Protozoos/química , Antígenos de Protozoos/genética , Linfocitos B/inmunología , Enfermedad de Chagas/inmunología , Enfermedad de Chagas/parasitología , Mapeo Epitopo/métodos , Proteínas de Escherichia coli/genética , Proteínas de Escherichia coli/metabolismo , Humanos , Epítopos Inmunodominantes/química , Epítopos Inmunodominantes/genética , Epítopos Inmunodominantes/inmunología , Datos de Secuencia Molecular , Péptidos/síntesis química , Péptidos/química , Péptidos/inmunología , Señales de Clasificación de Proteína/genética , Proteínas Recombinantes de Fusión/genética , Proteínas Recombinantes de Fusión/metabolismo , Secuencias Repetitivas de Ácidos Nucleicos/genéticaRESUMEN
Relatamos a adaptacao de uma tecnica para coleta de amostras (MFV) e outra para extracao, amplificacao de DNA de parasitas da malaria para diagnostico por PCR/ELISA. O metodo de coleta de amostras requer menos habilidade e economisa tempo e dinheiro, assim reduzindo a mais da metade o custo. O material e tambem adequado para analise genetica em especimens frescos ou estocados, preparados por este metodo
Asunto(s)
Ensayo de Inmunoadsorción Enzimática , Malaria/diagnóstico , Reacción en Cadena de la Polimerasa , Secuencias Repetitivas de Ácidos Nucleicos/inmunología , Pruebas Serológicas/métodosRESUMEN
The circumsporozoite (CS) protein of Plasmodium vivax consists of a central repeat region flanked by highly conserved non-repeat regions. Serum samples from 33 individuals with naturally acquired infections of P. vivax were tested for antibodies to four antigens representing the vivax CS protein. Three recombinant proteins containing different overlapping sequences in the non-repeat regions and either the entire central repeat region (vivax-1 and vivax-2) or two of the repeat sequences (vivax-3) were used as antigens in an enzyme-linked immunosorbent assay (ELISA). Antibodies to two other proteins, one (NS1(81)V20) containing the entire predominant repeat region (GDRAA/DGQPA) and the other (Pvk247) containing the variant repeat sequence (ANGAGNQPG) that was recently reported from Thailand were also measured by ELISA. Immunoglobulin G antibodies to the antigen representing the predominant repeat were present in 15% of the patients on the first day of treatment (day 0) and in 24% of the patients two weeks later (post-treatment). Six and 12% of the patients had IgG antibodies to the antigen containing the variant repeat on day 0 and post-treatment, respectively. A larger proportion of the sera had antibodies to the three antigens containing the non-repeat sequences; on the first day of treatment and two weeks later, 79 and 97% of the patients, respectively, had antibodies to vivax-1, vivax-2, and vivax-3. In this sample of Peruvians naturally infected with P. vivax, the most prevalent antibody responses were targeted to epitopes in the non-repeat region of the CS protein rather than to epitopes in the repeat region.(ABSTRACT TRUNCATED AT 250 WORDS)