Efficacious control of cytomegalovirus infection after long-term depletion of CD8+ T lymphocytes

Although the relative contribution of different immune effector
functions to clearing tissues of cytomegalovirus is controversial,
the contribution of CD8+ T lymphocytes has generally been accepted
as essential. In this report, we show that under certain conditions
the CD8+ T-lymphocyte subset can be dispensable for clearance of
cytomegalovirus. Mice depleted of the CD8+ T-lymphocyte subset
eliminated infectious virus with a clearance kinetics similar to
that of normal mice. Adoptive transfer studies revealed that the
limitation of virus spread required the cooperation between the
CD4+ subset and other cells. Comparison between protective
functions generated in fully immunocompetent and in CD8- mice
demonstrated that elimination of the CD8+ subset before infection
altered the quality of the antiviral immune response. The
compensatory protective activity gained by CD4+ cells in CD8- mice
was absent in normal mice recovering from virus infection.