Phylogenetic tree comparing the relatedness of the sequence of the S1 part of the spike glycoprotein of IB variants from USA and other parts of the world.
KeyAs a general rule, isolates less than 89% similar are different serotypes, with the exception that Conn 46 and Fla 18288 are 96% similar but are different serotypes, indicating that only a few changes in the right place are required to change the serotype.
Numbers denote percent similarity.

Phylogenetic tree provided by Dr. Mark Jackwood