Transmission of plant viruses in nature often involves vectors which are usually plant pests. A class of soil borne invertebrates acts in this way. Ectoparasitic nematodes belonging to the Longidoridae family are responsible for the transmission of viruses from the Nepovirus genus using a semipersistant, non circulative mechanism. This passive transmission occurs during the feeding process of the nematodes on actively growing roots. However, only a few longidorid nematodes are able to acquire and subsequently transmit 12 of the 32 known Nepovirus. This singularity reflects a highly specific and strong association between the virus and the vector likely via a putative receptor on the cuticular lining of the oesophageal tract. Using a reverse genetics approach, investigations on the Grapevine fanleaf virus/Xiphinema index virus-vector association showed that the transmission specificity is solely determined by the coat protein.