Date: March 23, 2017
Source: Forschungsverbund Berlin e.V. (FVB)
Cheetahs are categorized as vulnerable species, partly because they have been considered to be prone to diseases due to their supposed weak immune system. However, they are hardly ever sick in the wild. A research team from the German Leibniz Institute for Zoo and Wildlife Research (IZW) recently discovered that cheetahs have developed a very efficient innate "first line of defense" immunity to compensate potential deficiencies in other components of their immune system. The scientists have published their results in the open access journal Scientific Reports of the Nature Publishing Group.
Cheetahs have a relatively low genetic variability which means that, within a population, the individuals have a similar genetic makeup. This is also true for the major histocompatibility complex (MHC), a genome region that regulates the so-called "adaptive" immune system and is typically highly variable in animal species. The adaptive immune system provides a rapid and specific defense against pathogens, if they have been encountered previously. A low MHC variability should therefore result in a weak adaptive immune system and thus a high vulnerability to diseases. This is often the case in species with low MHC variability, but there are some exceptions, the cheetah indeed being one of them. "During our long-term study that begun in 2002, we investigated more than 300 free-ranging cheetahs that live on farmland in Namibia. We did not encounter any cheetah with symptoms of acute infections, nor did we detect lesions in the examined dead animals," explains Bettina Wachter, head of the cheetah research project.
How can cheetahs cope so well with pathogens despite their supposedly weak adaptive immunity? The immune system is divided into three components:(1) the constitutive innate immune system, which provides a rapid first line of defense against intruders, (2) the induced innate immune system such as the local and systemic inflammatory response, which enhances recovery and decreases pathogen growth, and (3) the adaptive immune system.