PREVALENCE OF HUMAN HERPESVIRUS-6 VARIANT-A AND VARIANT-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 r eaction and sequence-specific oligonucleotide probe hybridization in o rder to discriminate the A and B variants of human herpesvirus 6 (HHV- 6). Comparative DNA sequence analysis of portions of the U1102 (varian t A) and Z29 (variant B) genomes revealed polymorphic regions which al lowed for the synthesis of variant-specific and consensus oligonucleot ide probes. These probes were found to hybridize exclusively to their respective HHV-6 variants. This strategy was then further tested by ev aluating 16 clinical isolates derived from patients undergoing bone ma rrow transplantation to determine the subtype prevalence of HHV-6 infe ction in these patients. All clinical isolates were documented to be o f variant B, indicating that the majority of bone marrow transplantati on patients may be preferentially infected with this HHV-6 subtype. Th is oligotyping strategy may be useful in defining the relative prevale nce of HHV-6A and HHV-6B infections in patient populations potentially at risk for HHV-6 disease.