Potato yellow dwarf virus (PYDV) is the type member of the genus Nucleorhabdovirus. There are two different strains of PYDV based on their insect-vector specificity, namely SYDV (sanguinolenta) and CYDV (constricta). PYDV is considered a model system to study virus-vector relationship for agriculturally harmful rhabdoviruses. This book describes the complete characterization of nucleotide and ORF sequences of N (nucleocapsid) and P (Phosphoprotein) gene of SYDV from cDNA clones of both viral genomic and messenger RNAs. Comparison of the SYDV-N ORF with orthologous regions from other plant and animal rhabdoviruses showed statistically significant identity. Phylogenetic analysis based on consensus N-ORFs placed SYDV into the same group with other Nucleorhabdoviruses. Sub cellular localization studies of SYDV-N and P protein revealed that both proteins are exclusively nuclear localized. Taken together, this book reports a detailed analysis of the biology of SYDV-N and P protein at the molecular and cellular level for the first time towards the long-term goal to characterize the entire SYDV genome and to better understand SYDV-host interaction.