Since 1988, we have isolated HIV-1 from 614 HIV-1-infected persons (total s
ample=2,785) in Japan, During the past 12 years, we have found a decline in
the HIV-1 isolation rate in Japan, with two identifiable turning points, 1
991-1992 and 1996-1997, The two turning points correspond to shifts in anti
-HIV-1 therapy. These findings suggest that HIV-1 in Japan is currently bio
logically well controlled, probably due to anti-HIV-1 therapy. On the other
hand, this decline is inconsistent with the recent increase of genetic dru
g-resistant HIV-1 in Japan, Further studies are needed to clarify mechanism
s that might explain the discrepancy.