At high (5.0) as well as low (0.01) multiplicity of infection (MOI), MCMV growth was significantly reduced in the single Hs3st1 and Hs3st4 knockouts as well as in the double Hs3st1/4 knockouts, indicating that 3-O-sulfation of HS is important for HCMV infection (Fig 4). This evidence concerns the gene HS3ST1 and infection.