Prevalence of human herpesvirus 6 variant A and B infections in bone marrow transplant recipients as determined by polymerase chain reaction and sequence-specific oligonucleotide probe hybridization.

An oligotyping methodology was devised by using the polymerase chain reaction and sequence-specific oligonucleotide probe hybridization in order to discriminate the A and B variants of human herpesvirus 6 (HHV-6). Comparative DNA sequence analysis of portions of the U1102 (variant A) and Z29 (variant B) genomes revealed polymorphic regions which allowed for the synthesis of variant-specific and consensus oligonucleotide probes. These probes were found to hybridize exclusively to their respective HHV-6 variants. This strategy was then further tested by evaluating 16 clinical isolates derived from patients undergoing bone marrow transplantation to determine the subtype prevalence of HHV-6 infection in these patients. All clinical isolates were documented to be of variant B, indicating that the majority of bone marrow transplantation patients may be preferentially infected with this HHV-6 subtype. This oligotyping strategy may be useful in defining the relative prevalence of HHV-6A and HHV-6B infections in patient populations potentially at risk for HHV-6 disease.