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Chinese scientists discover different COVID-19 effect on various primate species

They have concluded that the most suitable for experiments are the rhesus macaques as displaying strongest symptoms

MOSCOW, April 13. /TASS/. Chinese medics have studied the effect of the novel coronavirus on various types of primates by observing the development of infection in three different monkey species: the rhesus macaque, the crab-eating macaque and the common marmoset. The first genus was found to be the most affected by the COVID-19 infection, the researchers say.

The virus traces were identified in blood samples, as well as secretions from nose, throat and other organs of all three ape genera, although heightened body temperatures were only observed in the rhesus macaques, the researchers say, adding that in some specimen, body temperature could reach up to 40.9 degrees Celsius. Overall, [rhesus macaques] turned out to be the most vulnerable to the COVID-19.

The first experiments, which involved infection of animals with the novel coronavirus (SARS-CoV-2), were conducted by the Chinese researchers in mid-February this year. These experiments confirmed that the virus can infect animal organisms and cause the same symptoms as in humans.

Later, US researchers conducted similar experiments on the rhesus macaques, proving that the SARS-CoV-2 cause the same symptoms as in humans, which makes this species a good model animal for testing of vaccines and virus research.

Remote relatives of humans

The scientists from the Chinese Academy of Sciences’ Institute of Medical Biology and their colleagues from the Guangdong Provincial Center for Disease Control and Prevention undertook to check, how vulnerable two other primate species, most commonly used in lab experiments, are to the COVID-19 disease — the crab-eating macaque (Macaca fascicularis) and the common marmoset (Callithrix jacchus).

The former are close relatives of the rhesus macaques, while the latter are very far from the evolution standpoint from both humans and macaques, as well as from other European primates. Despite that, marmosets are widely used as model animals in studies of infections, toxins and ageing.

The Chinese specialists have procured a dozen of each monkey species and attempted to infect them with large doses of the SARS-CoV-2 virus. Later, the researchers continuously observed changes in the primates’ health and sought traces of the virus in various parts of their bodies.

The observations revealed significant differences in the infection spread pattern. In particular, the coronavirus infection had almost no effect on the health of the marmosets. Traces of the virus were registered in their bodies, but the monkeys did not develop pneumonia or heightened body temperature.

By contrast, both macaque species developed trademark COVID-19 symptoms, although the symptoms were much stronger in the rhesus macaques than in their Java counterparts. In particular, all rhesus macaques developed severe fever, they lost between 6 and 30% of their body weight, and their lungs and heart displayed damage, characteristic of the SARS-CoV-2 infection.

The researchers have concluded that the first COVID-19 drugs and vaccines should be tested on the rhesus macaques and not on other monkeys that are less vulnerable to the coronavirus disease.