Feline immunodeficiency virus dendritic cell infection and transfer. 
Feline immunodeficiency virus (FIV) interacts with dendritic cells (DC) during initiation of infection, but whether DC support or transfer FIV infection remains unclear.  To address this issue, we studied the susceptibility of feline myeloid DC to FIV infection and assessed potential transfer of infection from DC to CD4(+) T cells.  FIV was detected in membrane-bound vesicles of DC within 2 h of inoculation, although only low concentrations of FIV DNA were found in virus-exposed isolated DC.  Addition of resting CD4(+) T cells increased viral DNA levels; however, addition of activated CD4(+) T cells resulted in a burst of viral replication manifested by FIV p27 capsid antigen generation.  To determine whether transfer of FIV infection required productively infected DC (vs virus bound to DC but not internalized), virus-exposed DC were cultured for 2 days to allow for degradation of uninternalized virus and initiation of infection in the DC, then CD4(+) T blasts were added.  Infection of T cells remained robust, indicating that T-cell infection is likely to be mediated by de novo viral infection of DC followed by viral transfer during normal DC/T-cell interactions.  We conclude that feline DC support restricted FIV infection, which nevertheless is sufficient to efficiently transfer infection to susceptible T cells and trigger the major burst of viral replication.  Feline DC/FIV/T-cell interactions (similar to those believed to occur in human immunodeficiency virus and simian immunodeficiency virus infections) highlight the means by which immunodeficiency-inducing lentiviruses exploit normal DC/T-cell interactions to transfer and amplify virus infection.