[Estimation of time detection limit for human cytochrome b in females of Lutzomyia evansi].

INTRODUCTION: Molecular biology techniques have allowed a better knowledge of sources of blood meals in vector insects. However, the usefulness of these techniques depends on both the quantity of ingested blood and the digestion process in the insect. OBJECTIVE: To identify the time limit for detection of the human cytochrome b (Cyt b) gene in experimentally fed females of Lutzomyia evansi. MATERIALS AND METHODS: Eight groups of L. evansi females were fed on human blood and sacrificed at intervals of 24 hours post-ingestion. Total DNA was extracted from each female and a segment of 358 bp of Cyt b was amplified. In order to eliminate false positives, amplification products were subjected to a restriction fragment length polymorphism (RFLP) analysis. RESULTS: The human Cyt b gene segment was detected in 86% (49/57) of the females of L. evansi, from 0 to 168 hours after blood ingestion. In 7% (4/57) of the individuals we amplified insect DNA, while in the remaining 7%, the band of interest was not amplified. We did not find any statistical differences between groups of females sacrificed at different times post-blood meal regarding the amplification of the human Cyt b gene segment or the number of samples amplified. CONCLUSION: The human Cyt b gene segment was detectable in L. evansi females up to 168 hours after blood ingestion.

Estimación del tiempo límite de detección del gen citocromo b de humanos en hembras de Lutzomyia evansi / Estimation of time detection limit for human cytochrome b in females of Lutzomyia evansi

Resumen Introducción. Las técnicas de biología molecular han permitido ampliar el conocimiento sobre las fuentes de ingestión de sangre de los insectos vectores. Sin embargo, la utilidad de estas técnicas depende de la cantidad de sangre ingerida y del proceso de digestión en el insecto. Objetivo. Determinar el tiempo límite de detección del gen citocromo b (Cyt b) de humanos en hembras de Lutzomyia evansi alimentadas experimentalmente. Materiales y métodos. Se evaluaron ocho grupos de hembras de L. evansi alimentadas con sangre humana, las cuales fueron sacrificadas en intervalos de 24 horas desde el momento de la ingestión sanguínea. Se extrajo el ADN total de cada hembra y se amplificó un segmento de 358 pb del gen Cyt b. Los productos amplificados fueron sometidos a un análisis de polimorfismos en la longitud de los fragmentos de restricción (Restriction Fragment Length Polymorphism, RFLP), con el fin de descartar falsos positivos. Resultados. El segmento del gen Cyt b de humanos fue detectado en 86 % (49/57) de las hembras de L. evansi a partir de las 0 horas y hasta 168 horas después de la ingestión de sangre. En 7 % (4/57) de los individuos se amplificó el ADN del insecto y en el 7 % restante no se amplificó la banda de interés. No se encontraron diferencias estadísticas en cuanto a la amplificación del segmento del gen Cyt b de humanos ni al número de muestras amplificadas entre los grupos de hembras sacrificadas a distintas horas después de la ingestión. Conclusión. El segmento del gen Cyt b de humanos fue detectable en hembras de L. evansi hasta 168 horas después de la ingestión de sangre.

Abstract Introduction: Molecular biology techniques have allowed a better knowledge of sources of blood meals in vector insects. However, the usefulness of these techniques depends on both the quantity of ingested blood and the digestion process in the insect. Objective: To identify the time limit for detection of the human cytochrome b (Cyt b) gene in experimentally fed females of Lutzomyia evansi. Materials and methods: Eight groups of L. evansi females were fed on human blood and sacrificed at intervals of 24 hours post-ingestion. Total DNA was extracted from each female and a segment of 358 bp of Cyt b was amplified. In order to eliminate false positives, amplification products were subjected to a restriction fragment length polymorphism (RFLP) analysis. Results: The human Cyt b gene segment was detected in 86% (49/57) of the females of L. evansi, from 0 to 168 hours after blood ingestion. In 7% (4/57) of the individuals we amplified insect DNA, while in the remaining 7%, the band of interest was not amplified. We did not find any statistical differences between groups of females sacrificed at different times post-blood meal regarding the amplification of the human Cyt b gene segment or the number of samples amplified. Conclusion: The human Cyt b gene segment was detectable in L. evansi females up to 168 hours after blood ingestion.