Monoclonal antibodies prevent COVID-19 inflammation in macaques

Monoclonal antibodies protected aged, type 2 diabetic rhesus macaque monkeys from disease due to SARS-CoV-2 and reduced signs of inflammation, including in cerebrospinal fluid, according to a new study from researchers at the University of California Davis, US.

“COVID-19 is more severe in elderly people and those with pre-existing conditions,” explained Associate Professor Smita Iyer, investigator on the study. “The elderly and diabetics tend to be immunosuppressed, but if you can get antibody levels high enough, you can prevent severe infection.”  Immune responses induced by vaccines are very effective at preventing severe disease and death, however an overwhelming inflammatory immune response could also be responsible for much of the damage of severe infections. 

According to the team, these signs of inflammation in the central nervous system (CNS) may be connected to neurological symptoms of COVID-19 disease in humans and possibly “long COVID” in which patients experience an array of symptoms for months after infection. 

The COVID infections in rhesus macaques were generally mild, especially in animals pre-treated with monoclonal antibodies, while control animals had more signs of inflammation in their lungs. Furthermore, the researchers also found infiltration of activated T cells into the cerebrospinal fluid of control animals a week after infection and they did not find any viral RNA in the cerebrospinal fluid. However, macaques treated with the monoclonal antibodies did not show inflammation in the cerebrospinal fluid. 

The data show that neutralising antibodies prevent the adverse inflammatory consequences of SARS-CoV-2 infection, the authors claimed. The results, detailed in Cell Reports, also help explain how antibodies, whether induced by vaccines or after infection, or given as a treatment, can affect the course of disease and suggest that antibodies could be given as a preventative treatment to people at high risk, such as elderly residents during an outbreak in a nursing home.