Evaluation of three different DNA extraction methods from blood samples collected in dried filter paper in Plasmodium subpatent infections from the Amazon region in Brazil Avaliação de três métodos de extração de DNA obtidos de amostras de sangue coletadas em papel de filtro em infecções subpatentes de Plasmodium da região Amazônica no Brasil

• Main Authors: Renata Bortolasse Miguel, José Rodrigues Coura, Franklyn Samudio, Martha Cecília Suárez-Mutis
• Format: Article
• Language: English
• Published: Universidade de São Paulo 2013-06-01
• Series: Revista do Instituto de Medicina Tropical de São Paulo
• Subjects: Malaria; Asymptomatic Plasmodium infection; Molecular diagnostic; DNA extraction methods
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0036-46652013000300205

Asymptomatic Plasmodium infection is a new challenge for public health in the American region. The polymerase chain reaction (PCR) is the best method for diagnosing subpatent parasitemias. In endemic areas, blood collection is hampered by geographical distances and deficient transport and storage conditions of the samples. Because DNA extraction from blood collected on filter paper is an efficient method for molecular studies in high parasitemic individuals, we investigated whether the technique could be an alternative for Plasmodium diagnosis among asymptomatic and pauciparasitemic subjects. In this report we compared three different methods (Chelex&#174;-saponin, methanol and TRIS-EDTA) of DNA extraction from blood collected on filter paper from asymptomatic Plasmodium-infected individuals. Polymerase chain reaction assays for detection of Plasmodium species showed the best results when the Chelex&#174;-saponin method was used. Even though the sensitivity of detection was approximately 66% and 31% for P. falciparum and P. vivax, respectively, this method did not show the effectiveness in DNA extraction required for molecular diagnosis of Plasmodium. The development of better methods for extracting DNA from blood collected on filter paper is important for the diagnosis of subpatent malarial infections in remote areas and would contribute to establishing the epidemiology of this form of infection.<br>Infec&#231;&#227;o assintom&#225;tica por Plasmodium &#233; um novo desafio para a sa&#250;de p&#250;blica no Brasil. A rea&#231;&#227;o em cadeia da polimerase (PCR) &#233; o melhor m&#233;todo para detectar baixas parasitemias presentes em pacientes com infec&#231;&#227;o assintom&#225;tica. Nas &#225;reas end&#234;micas, a coleta de sangue total &#233; dificultada pela distancia geogr&#225;fica, transporte e adequada armazenagem das amostras. A coleta de sangue em papel de filtro pode ser uma alternativa nessas &#225;reas de dif&#237;cil acesso. Neste estudo foram comparados tr&#234;s diferentes m&#233;todos de extra&#231;&#227;o de ADN a partir de papel de filtro usando como controle extra&#231;&#227;o a partir de sangue total. O protocolo Chelex&#174;-Saponina foi o que obteve o melhor resultado quando comparado com os outros tr&#234;s protocolos. No entanto a sensibilidade foi de 66,7% para o P. falciparum e 31,6% para o P. vivax. Conclui-se que em caso de infec&#231;&#227;o assintom&#225;tica o papel de filtro n&#227;o &#233; ainda uma boa alternativa para coleta de amostras.