1. Department of Virology, Aggeu Magalhães Institute, Oswaldo Cruz Foundation, Recife, 50740-465, Brazil
2. Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, ITQB NOVA, Oeiras, 2780-157, Portugal
3. Department of Fundamental Chemistry, Federal University of Pernambuco, Recife, 50740-540, Brazil