The genetic relatedness of United States prototype bluetongue viruses by RNA/RNA hybridization.

The genetic relatedness of the prototype bluetongue viruses isolated in the United States was examined by RNA/RNA hybridization. Genomic dsRNAs of bluetongue viruses were separated by either SDS-PAGE or NuSieve agarose gel electrophoresis and were blotted by both standard Northern technique and the recently developed rapid alkali-blotting method of Li, Kowalik, and Parker (submitted for publication) to positively charged nylon membranes. The blotted RNA was then probed with 3'-end-labeled dsRNA of each serotype. Initially, single segments were individually hybridized to identify cognate genes. Total genomic dsRNAs were then probed to determine genetic relatedness. The genes coding for the nonstructural proteins NS1 and NS2 were the most conserved. Most of the RNA segments coding for the core proteins were also well conserved, with segment S1 showing some diversity among the five serotypes. The outer capsid protein-coding segments demonstrated a wide degree of sequence divergence with segment L2 having little or no cross-hybridization among the five serotypes.