Institute for Adriatic Crops and Karst Reclamation 1 article published in JoVE Immunology and Infection Fluorescence in situ Hybridizations (FISH) for the Localization of Viruses and Endosymbiotic Bacteria in Plant and Insect Tissues Adi Kliot1,2, Svetlana Kontsedalov1, Galina Lebedev1, Marina Brumin1, Pakkianathan Britto Cathrin1, Julio Massaharu Marubayashi1, Marisa Skaljac1,3, Eduard Belausov4, Henryk Czosnek2, Murad Ghanim1 1Department of Entomology, Volcani Center, 2Institute of Plant Sciences and Genetics in Agriculture, Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, 3Department of Applied Sciences, Institute for Adriatic Crops and Karst Reclamation, 4The Institute of Plant Sciences, Volcani Center We describe here a simple fluorescence in situ hybridization (FISH) method for the localization of viruses and bacteria in insect and plant tissues. This protocol can be extended for the visualization of mRNA in whole mount and microscopic sections.