Neither Human Herpesvirus 8 nor a related variant could be detected in bone marrow stromal cells from multiple myeloma patients.

The possibility has been raised that either a human herpesvirus-
8 (HHV-8) variant or a novel, unidentified, g-herpesvirus
related to HHV-8 is frequently associated with multiple
myeloma (MM), which could explain the lack of antibodies to
HHV-8 antigens and the discordant results from polymerase
chain reaction (PCR) studies of HHV-8-specific sequences in
MM patients. Thus, we used a sensitive PCR assay with degenerate
primers targeting the highly conserved DNA polymerase
gene of the herpesvirus family to examine the longterm
cultures of bone marrow stromal cells (BMSCs) from
19 MM, 3 monoclonal gammopathies of undetermined significance
and 6 control patients. Both the culture supernatant
and the adherent stromal layer were examined from the 2nd
until the 8th week of culture to assess the immunophenotype
of the various cell types harvested for the molecular analysis.
BMSCs consisted of a mixed population of fibroblast, macrophage,
dendritic and endothelial cells. An amplified product
of the expected size was obtained only in 3 MM cases, both in
the adherent and nonadherent fractions. Direct sequencing
and alignment of the nucleotide and amino acid sequences
showed that the DNA sequences were 100% identical to
Epstein-Barr virus (EBV) DNA. The PCR positivity was due
to the presence of EBV-infected lymphoblastoid cells with
plasmacytoid features, expressing the EBV-encoded latent
membrane protein-1 and detectable either in the stromal
cells or in the culture supernatant. Our data do not support
a causal role of either HHV-8 or a novel herpesviral variant
related to HHV-8 in MM.