Early Suppression of Viremia by ZDV Does Not Alter the Spread of Feline Immunodeficiency Virus Infection in Cats

Antiviral Therapy Reduces Viral Burden but Does Not Prevent Thymic Involution in Young Cats Infected with Feline Immunodeficiency Virus

“…While viral DNA was disseminated throughout most lymphoid tissues at 70 days p.i., viral RNA was produced almost exclusively in the thymus during the acute phase of infection (18). We have demonstrated heavy viral burden in the thymic tissues of FIV-infected young cats monitored for over 1 year (11), suggesting a strong correlation between virus infection of the thymus and subsequent pathologic change. However, in this study, thymic pathology was not proportional to virus load in the ZDV-treated FIV-infected cats.…”

“…Lymphocyte subpopulations in peripheral blood were enumerated by immunostaining and flow cytometry as previously described (10,11).…”

“…FIV infection leads to progressive impairment of immune function (in vitro mitogen responsiveness, loss of delayed-type hypersensitivity, opportunistic infections, and neoplasia) and depletion in the peripheral pool of CD4 T lymphocytes which occurs over a period of months to years (9,13,20,28,32). Further, the thymus of FIV-infected cats carries a heavy viral burden (3,7,11,30,31). Thymic function is compromised in the face of extensive pathological change in the tissue.…”

“…Previous work in the FIV model system showed that prophylactic ZDV monotherapy was effective in reducing acute CD4 lymphocyte loss in young cats inoculated with FIV during the drug treatment period (4 weeks) and yet did not prevent infection and later CD4 lymphocyte decline (10,11). More directly, another study of chronically infected adult cats (Ͼ6 months of age) placed on ZDV therapy for 12 weeks revealed that the thymuses of treated cats increased in overall cellularity as well as in numbers of CD1-, CD4-, and CD8-positive lymphocytes (K. A. Hayes and L. E. Mathes, unpublished data).…”

Lentiviral Neuropathogenesis: Comparative Neuroinvasion, Neurotropism, Neurovirulence, and Host Neurosusceptibility

“…Variables that cannot be controlled in the context of HIV-1 infections can be examined in nonhuman lentivirus systems, including control of age, antiretroviral therapies, viral strain, route and timing of infection, and accessibility to tissue samples that is not possible in humans. In addition, SIV and SHIV have been utilized in HIV-1 vaccine development (3,44,48,69), and FIV has been used for therapeutic studies (9,49). Lentiviral animal models also permit evaluation of viral evolution together with host pathogenic responses and thus represent invaluable tools to enhance the understanding of lentivirus neuropathogenesis.…”