The key finding unearthed by virologists is that the relatively strong immune system of the bat is the principal reason for viruses associated with bats having a higher virulence. In turn, this makes viruses that can be spread from bats to people relatively more pathogenic and, in some circumstances, more deadly.
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The research from University of California – Berkeley looked at cultured bat cells and this indicated that the strong immune response of the bat, which needs to be constantly primed in order to respond to viruses as a virtue of the habitat of the mammal, is the primary reason why some viruses are of greater virulence.
The biologically observed data was subsequently modeled on a computer. This exercise revealed that as bat cells release interferon as an infection occurs, other cells within the body of the bat rapidly block themselves off. This absence of other, available cells triggers viruses to engage in faster reproduction. The effect of this is an increased level of both virulence factor and infectivity.
These factors of virulence and infectivity pose greater challenges for when bat-derived viruses go on to infect animals with less robust immune systems. Those with relatively weaker immune systems includes humans. So, while the bat has evolved a robustness to viruses, those animals subsequently infected have to contend with some very potent forms of viruses.
The evolution of viruses in bats was demonstrated on two species: Egyptian fruit bat (Rousettus aegyptiacus), in relation to the Marburg virus; and the Australian black flying fox (Pteropus alecto), using the Hendra virus. the virus is a rare, but emerging, zoonosis that causes severe and often fatal disease in both infected horses and humans.
The research also demonstrated by bats have a high association with zoonotic infections, compared with other animals. This comes down to stress and environmental factors impacting on bat habitat.
The scientists were able to demonstrate that the disruption of bat habitats causes stress to the bats; and this makes the stressed bats shed greater quantities of virus in their saliva, urine and feces. This viral shedding increases the possibility of zoonosis – the infection of other animals.
The research study has been published in the journal eLife, where the study is titled “Accelerated viral dynamics in bat cell lines, with implications for zoonotic emergence.”
