**Acknowledgement**

This work was supported by grants from the Colombian Science, Technology and Innovation Department (COLCIENCIAS) programmes Ecos-Nord and Jóvenes Investigadores P 2009- 0745, by the Universidad Nacional de Colombia's Research Department and Fundacion Instituto de Inmunología de Colombia (FIDIC). We would like to extend our most sincere thanks to Marcela Camacho, Marie France van den Hove, Thierry Pourcher, Jean-François Denef, Hernando Curtidor and Manuel E Patarroyo for their support and encouragement for carrying out basic research in Colombia.

We would also like to thank the students who carried out and who are carrying out BSc, MSc and PhD thesis experiments: Sandra Perdomo, Gabriela Delgado, Cristina Zapata, Ricardo Cabezas, Alejandro Ondo, Leslie Leal, Oscar Vivas, Claudia Moreno, Eleonora Bernal, Anyela González, Mauren Ortíz, Carolina Ochoa and Luz Marina Porras; this work could not have been completed without their input.
