Hamsters present similar reactions to Covid-19 as humans, with the highest quantity of the virus in the beginning of the infection and its complete removal by three weeks, a study by the Indian Council of Medical Research (ICMR) has shown. Mice, however, did not show any susceptibility to the virus.
Mice and hamsters are used in medical research as they have a biological makeup similar to humans, besides being low-cost and having the ability to reproduce swiftly.
Researchers from ICMR institutions studied the responses of 16 mice and 18 hamsters to a novel cononavirus (SARS-CoV-2) sample from an infected person. The rodents did not show any clinical signs or mortality from the virus.
The study also found that the transmission of the virus was the most on the third and fifth day, mirroring evidence that human cases are the most infectious in the early stages.
The hamsters presented more reactions to the virus. “The viral RNA could be detected in nasal turbinates, trachea, lungs, spleen and kidney on Day 3, post inoculation”, indicating the day of the highest viral loads (or amount of the virus), the study stated.
On Day 3, the highest viral loads were first observed in their lungs, then their trachea, nasal pathways, kidneys, and intestines. “This shows resemblance to the upper and lower respiratory tract affinity of SARS-CoV-2 in humans and the higher viral loads observed during the acute phase of infection,” it said.
The hamsters began to clear the virus from their organs by the fifth day for small intestines, kidneys by Day 7, and trachea by Day 10. The virus remained in their lungs and nasal pathways for 14 and 21 days, respectively. “This observation was in line with a recent study that reported viral shedding up to a median period of 20 days in Covid-19 survivors,” it said.
The hamsters also lost weight from Days 2 to 6, but later gained it back. The mice, on the other hand, had no antibodies for the virus, indicating that they were not susceptible to it.
The research was conducted at the Maximum Containment Laboratory at ICMR, National Institute of Virology, Pune. Authors included prominent ICMR officials such as Nivedita Gupta and R R Gangakhedkar.
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