Pathological manifestations of feline immunodeficiency virus (FIV) infection in wild African lions

Challenging the assumption that FIV is harmless in its natural hosts, this study examined wild African lions for clinical and pathological signs associated with feline immunodeficiency virus infection. By comparing FIV-positive and FIV-negative lions, the authors found that infected animals showed immunological perturbations, including altered lymphocyte subsets and evidence consistent with AIDS-like immune dysfunction. The work suggested that even endemic, long-co-evolved lentiviruses can impose subtle fitness and immune costs on wild felids, rather than being entirely benign. This nuanced view mattered for conservation, implying that FIV could increase vulnerability to co-infections such as distemper or tuberculosis. It pushed researchers to look beyond simple seropositivity and consider sublethal disease effects when assessing pathogen threats to endangered cat populations.