For monitoring retroviral infection on the gene level, we propose the
use of quantitative PCR with two internal standards: one for a fragmen
t of the viral genome and the other for the host cell marker gene. The
standards (one for HIV and the other for a human DNA marker gene HLA-
DQ alpha) were constructed by PCR-mediated joining of DNA fragments an
d were found to be effective in quantitative PCR despite rather differ
ent structures of amplified fragments in target and standard DNAs. The
number of HIV DNA copies was found to be 2-500 per 1000 lymphocytes i
n blood from HIV-infected patients and up to 5000 + per 1000 cells in
chronically infected cell lines. The degree of infection thus measured
was found to change over the course of treatment.