Contrasting clinical outcomes in two cohorts of cats naturally infected with feline immunodeficiency virus (FIV)

Abstract

HighlightsMulti-cat household animals displayed 63% mortality rate.Lymphoma was the most common cause of death.The CD4:CD8 ratio failed to distinguish cats classified as healthy and not healthy.FIV load failed to distinguish cats classified as healthy and not healthy.Management and housing conditions impact on the progression of FIV infection.

Central and peripheral reservoirs of feline immunodeficiency virus in cats: a review

“…Although FIV has been associated with unfavourable outcomes such as opportunistic infections, neoplasia, wasting and death, the precise determinants of morbidity remain unclear. Contributory factors including viral/host genetics, age of host, viral load during acute virus infection, housing environment, stress, cohabitation with other cats and concurrent disease status have been proposed [7][8][9][10][11][12]. Efforts to control lentiviral infections primarily focus on two broad strategies: preventing new infections and suppressing viral replication in already infected individuals, both of which are particularly relevant for HIVinfected humans.…”

“…Numerous reports have described the virologic and immunopathologic aspects of acute and early asymptomatic phases of FIV infection through experimental inoculation studies. However, investigation of the late asymptomatic phase and transition into FAIDS has been primarily restricted to clinical cohorts of cats naturally infected with FIV [7,23,25]. This is perhaps due to the cost of maintaining and housing experimentally infected cats in specific pathogen free (SPF) facilities for prolonged time frames.…”

“…Importantly, relatively few studies have monitored the frequency of CD4+ and CD8+ T cell subsets into the late stages of infection. However, findings from these few studies, including experimental and natural infections, show that CD4+ T cell counts continue to progressively decline to very low levels in blood and lymphoid tissues and may be associated with declining peripheral CD8+ T cell frequencies and clinical signs of immunodeficiencies [7,19,83]. Interestingly, significant declines in CD4+ T cells counts are not always associated with clinical signs of acquired immunodeficiencies and other factors such as environmental stresses may determine disease onset [7,24,79].…”

“…McDonnel et al reviewed FIV latency and the strengths of the FIV-infected cat as a model of the HIV-infected human [61]. Different cohorts of naturally and experimentally infected cats have demonstrated either undetectable or consistently detectable plasma viraemia during the asymptomatic phase, which may be due to differences in viral strains, inoculating dose, age of the animal or other factors [7,84,98,104,[115][116][117][118]. The cellular mechanisms involved in FIV latency have been identified in both in vitro and in vivo infection systems [52,84,[119][120][121][122].…”

“…However, any relationship between FIV integration sites and virus latency is currently undetermined. Furthermore, in contrast to HIV-1 infection, FIV latency may be apparent in the absence of ART and a common characteristic in cats naturally infected with FIV, particularly in environments free of stress and exposure to other pathogens, such as a single-cat household [7]. However, this dissimilarity suggests that FIV infection may provide a unique opportunity to examine mechanisms and interventions of lentiviral latency in the absence of ART.…”