Am. Beebe et al., PRIMARY STAGE OF FELINE IMMUNODEFICIENCY VIRUS-INFECTION - VIRAL DISSEMINATION AND CELLULAR TARGETS, Journal of virology, 68(5), 1994, pp. 3080-3091
The objective of this study was to identify cellular and organ targets
of acute feline immunodeficiency virus (FIV) infection in vivo. Tissu
es of FIV-infected cats were studied at eight time points during the f
irst 3 months after experimental infection. FIV nucleic acids were fir
st detected by in situ hybridization 21 days after infection, approxim
ately 1.5 weeks after lymph node enlargement was first observed and 3
weeks before the primary acute flu-like illness. The majority of FIV-i
nfected cells were present in lymphoid organs, though low numbers of i
nfected cells were noted in nonlymphoid organs as well. Germinal cente
rs harbored many of the FIV-infected cells within lymphoid tissues. Th
e thymic cortex was also a major site of early infection. Combined in
situ hybridization and immunohistochemistry revealed that T lymphocyte
s were the primary target of early FIV infection in tissues of cats be
fore the onset of clinical signs of acute illness. An unidentified pop
ulation of mononuclear sells and a few macrophages were also infected.
During the ensuing acute flu like illness, the proportion of FIV-infe
cted macrophages in tissues increased dramatically. This early shift i
n the predominant cellular localization of FIV from T lymphocytes to m
acrophages may be important for establishing viral persistence.