A collaborative team of researchers from the University of Wisconsin-Madison, the University of Tokyo, and the Icahn School of Medicine at Mount Sinai have discovered that a previous infection from the SARS-CoV-2 virus elicits immunity. Additionally, they also analyzed how convalescent serum limits the replication of viruses in hamsters' lungs.
The findings of the study were published in the clinical journal Proceedings of the National Academy of Sciences on June 22, 2020.
Hamsters, the Perfect Animal Model for Coronavirus Tests
Syrian hamsters are deemed to be the ideal animal models for researchers trying to understand the SARS-CoV-2 virus. They could be used in trials for evaluating vaccines, drugs, and other treatment methods for COVID-19.
According to Yoshihiro Kawaoka, the lead author of the study, hamsters are good models for human influenza and SARS-CoV. Furthermore, the professor of pathobiological sciences at the UW School of Veterinary Medicine and virology professor at the University of Tokyo says that he and his team wanted to see if the disease course is similar to humans in these animals from start to end.
Another study conducted by scientists at the University of Hong Kong also showed Syrian hamsters to be a good model for COVID-19-related research. In the study, the hamsters were made to wear surgical face masks. The researchers found that the practice indeed lessened the transmission of the virus.
According to Samantha Loeber, a co-author of the recent study and a veterinarian and radiologist at UW Veterinary Care, hamsters infected with the coronavirus share the same CT imaging characteristics as humans with the same infection.
Previous COVID-19 Infection Brings Out Immunity
In the clinical experiment, the researchers exposed the virus to the hamsters and within six days were able to detect the virus in the animals' respiratory organs. Some were also detected in their brains.
To determine whether the animals developed immunity, another round of the virus was administered to the animals. After three weeks following the initial infection, the researchers were not able to detect any virus in the hamsters' respiratory tracts.
They did, however, find the virus in the airways of the control group of hamsters not previously infected with COVID-19. According to Pete Halfmann, a research professor in Kawaoka's U.S. lab, the animals were found to possess antibodies and did not get reinfected.
He adds that the findings suggest that the hamsters have developed an immunity. However, they remain unsure of how long the protection would last.
Convalescent Treatment Effective in Hamsters
Convalescent plasma therapy involves infusing antibody-laden blood plasma from a person who recovered from a certain disease to another person still suffering from the illness. As a result, the antibodies from the plasma would help the body combat the disease.
It is currently an experimental therapy done in COVID-19 patients. Studies on the treatment method are still limited, although it has shown favorable results in most.
To test the approach in hamsters, the researchers extracted convalescent sera from previously ill hamsters and then blended it together. They infected new hamsters with SARS-CoV-2 and then administered the antibody-laden sera one day or two days after the infection.
Within a day of the infection, the hamsters were found to have lower levels of the virus in their lungs and nasal pathways compared to hamsters who received a placebo.
Another study published last week in the journal Science exhibited that transfusion of human antibodies to hamsters also proves to be protective of the coronavirus infection.
According to Kawaoka, although using convalescent serum as a treatment for coronavirus is still in its experimental stages, the findings of the study shows that it could eventually become a part of an effective treatment for COVID-19 in humans.
