Passive infusion of immune serum into simian immunodeficiency virus-infected rhesus macaques undergoing a rapid disease course has minimal effect on plasma viremia
Jm. Binley et al., Passive infusion of immune serum into simian immunodeficiency virus-infected rhesus macaques undergoing a rapid disease course has minimal effect on plasma viremia, VIROLOGY, 270(1), 2000, pp. 237-249
Antibody responses are often considered to play only a limited role in cont
rolling viremia during chronic infections with human or simian immunodefici
ency virus (SIV). We investigated this by determining the effect of passive
ly infused antibody on plasma viremia in infected rhesus macaques. The emph
asis of the study was to understand the mechanism(s) underlying any observe
d effects. We infused serum immunoglobulins (SIVIG) purified from SIV(mac)2
51-infected macaques into other SIV(mac)251-infected macaques. The rapid pr
ogressor recipients had high Viral loads but negligible titers of antibodie
s to SIV. Thus, we could significantly increase antibody liters with exogen
ous SIVIG. Despite restoring anti-SIV titers to levels typical of macaques
with a normal disease course, SIVIG had only a modest effect on plasma SIV
RNA and cell-associated viral load; the maximum, transient, reduction was t
hreefold. The decrease in plasma RNA commenced within 1-2 h of SIVIG infusi
on, the nadir was at 12 h, and then a rebound occurred. A two- to threefold
drop in cell-associated viral RNA was simultaneous with the decrease in pl
asma RNA. The kinetics of the viremia changes are inconsistent with neutral
ization of new cycles of infection. More likely, perhaps unexpectedly is th
at infused antibodies killed SIV-infected cells, via an effector mechanism
such as antibody-dependent cellular cytotoxicity. (C) 2000 Academic Press.