Biology Reference
In-Depth Information
antibodies to the induction of cellular responses. Previous studies used
the gag to show the correlation between strong cytotoxic T-cell activ-
ity and reduced viral load. However, more recent data obtained in a
rhesus macaque challenge model suggest that cellular responses
focused on a single epitope may not be sufficient either to effectively
control viral replication.
4-7
It remains to be seen if increasing the
breadth of CTL responses will have a positive impact on the outcome
of challenge infection. Hence, it is now believed that humoral, cellu-
lar, and T-helper cell responses, both at peripheral and mucosal sites,
are needed for broad and durable protection against HIV.
Conceptually, antibodies would serve as a first line of defense by com-
pletely preventing infection (Fig. 1A) or reducing the virus inoculum,
whereas cellular responses would facilitate the clearance of HIV-
infected CD4
+
T-cells that escape antibody-mediated neutralization
Fig. 1.
Two potential outcomes for a preventative HIV vaccine. In the
graphs, the black line shows time course of viremia in the absence of vac-
cination. In panel A, the blue line indicates the virologic outcome in the case
of antibody-mediated (neutralization and ADCC) complete protection. In
panel B, the blue line indicates the outcome in the case of a vaccine that
induces partial protection and reduces the disease where both humoral and
cellular responses participated.
