Thursday, July 14, 2016

Viruses detected on plants chewed by primates

New research has discovered a noninvasive way to test primates for viruses. Collaboration between UC Davis and Gorilla Doctors has shown that the plants mountain gorillas (Gorilla beringei beringei) and golden monkeys (Cercopithecus mitis kandti) consume and discard can be collected and analyzed to determine what viruses the animals have. Blood samples and oral and rectal swabs all require the researcher to anesthetize the animal, something that is not done with critically endangered mountain gorillas unless absolutely necessary.
Thus, this new noninvasive method will allow researchers to detect viruses simply by following the animals at a distance and collecting any bits of chewed bark, leaves, or fruit the individual discards. For this study, Smiley Evans and colleagues (2016) spent almost a year collecting these vegetation discards from 294 gorillas from 26 different family groups across the Volcanoes National Park, Bwindi Impenetrable Forest, and Mgahinga Gorilla Park.

The authors also looked at golden monkeys, collecting plant samples on three different dates in order to determine if their methods could be used on other primate species. Samples were collected from 18 individuals. For both species, researchers observed the animals, collected disregarded plant parts, and sampled from plants with visible bite marks and saliva.

It was possible to collect samples from nearly every individual in a family, including infants who may not consume the plants but still bite and chew them. DNA and RNA viruses were both successfully detected using this method with minimal disruption. Compared to other methods, Smiley Evans and colleagues were able to sample more individuals with less risk and little behavioral disruption. Using this method, the researcher easily knows the age of the sample because close behavioral observation is required.

Golden monkeys proved more challenging than mountain gorillas because they are arboreal and handle food less with their mouths when compared to mountain gorillas. However, it is still possible to collect samples, but researchers should prepare to collect fewer samples per visit.

This research is especially important for mountain gorillas because infectious diseases are one of the greatest threats to this species, and as wildlife increasingly comes into contact with humans, breakthroughs in disease ecology have the potential to positively impact these gentle giants. Roughly 60% of the remaining 880 mountain gorillas are habituated to humans (Gray et al., 2011; Robbins et al., 2011), meaning they encounter humans, whether tourists, researchers, or others, on a regular basis and are accustomed their presence.

Links of possible interest: 

Mountain gorilla genome sequenced

Works cited:
Gray, M., Fawcett, K., Basabose, A., et al., (2011). Virunga Massif Mountain Gorilla Census 2010 Summary Report. International Gorilla Conservation Programme.

Robbins, M. M., Roy, J., Kato, R., Kabano, P., Basabose, A., Tibenda, E., ... & Gray, G. (2011). Bwindi Mountain Gorilla Census 2011-Summary of Results. Uganda Wildlife Authority, 28.

Smiley Evans, T., Gilardi, K. V., Barry, P. A., Dsebide, B. J., Kinani, J. F., Nizeyimana, F., ... & Mazet J. A. (2016). Detection of Viruses Using Disregarded Plants from Wild Mountain Gorillas and Golden Monkeys. American Journal of Primatology.

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