Association of gH and gO genotypes in 236 complete HCMV genome sequences in the NCBI database. Complete HCMV genome sequences were retrieved from the NCBI nucleotide database using the keywords filter <human herpesvirus type 5 complete genome>. The resulting set of 350 sequences was curated to remove duplicates or genomes missing any of the UL74(gO) and UL75(gH) open reading frames, generating a working set of 236 complete HCMV genomes, which were analyzed using MAFFT FFT-NS-i (v7.429) phylogeny software. UL74(gO) and UL75(gH) sequences were assigned to their respective genotype groups as defined previously: UL75(gH) genotypes 1 and 2 (57, 61) and UL74(gO) genotypes 1a, 1b, 1c, 2a, 2b, 3, 4, and 5 (10, 12). Shown is a phylogenetic tree of the 8 gO genotypes with the frequency of pairing with either gH1 or gH2. Asterisks indicate gO genotypes that were not analyzed in the experiments described herein.