A Recombinant Sendai Virus Is Controlled by CD4 + Effector T Cells Responding to a Secreted Human Immunodeficiency Virus Type 1 Envelope Glycoprotein

Abstract

ABSTRACT The importance of antigen-specific CD4 + helper T cells in virus infections is well recognized, but their possible role as direct mediators of virus clearance is less well characterized. Here we describe a recombinant Sendai virus strategy for probing the effector role(s) of CD4 + T cells. Mice were vaccinated with DNA and vaccinia virus recombinant vectors encoding a secreted human immunodeficiency virus type 1 (HIV-1) envelope protein and then challenged with a Sendai virus carrying a homologous HIV-1 envelope gene. The primed mice showed (i) prompt homing of numerous envelope-primed CD4 + T cell populations to the virus-infected lung, (ii) substantial production of gamma interferon, and interleukin-2 (IL-2), IL-4, and IL-5 in that site, and (iii) significantly reduced pulmonary viral load. The challenge experiments were repeated with immunoglobulin −/− μMT mice in the presence or absence of CD8 + and/or CD4 + T cells. These selectively immunodeficient mice were protected by primed CD4 + T cells in the absence of antibody or CD8 + T cells. Together, these results highlight the role of CD4 + T cells as direct effectors in vivo and, because this protocol gives such a potent response, identify an outstanding experimental model for further dissecting CD4 + T-cell-mediated immunity in the lung.