A new monoclonal antibody (mAb) cocktail appears to be a promising candidate for prophylactic use and for therapy in early Covid-19 cases which have not progressed to severe disease, according to a study by the Indian Council of Medical Research – National Institute of Virology.
The mAb cocktail ZRC-3308, developed by Zydus Cadila Healthcare Limited, Gujarat, has shown effective prophylactic and therapeutic activity against SARS-CoV-2 infection in Syrian hamsters.
Zydus Cadila, a pharmaceutical company, had earlier announced that its biological therapy ZRC-3308, a cocktail of two SARS-CoV-2-neutralising monoclonal antibodies (mAbs), can emerge as one of the main treatments for mild Covid-19. The therapy is a cocktail of two monoclonal antibodies which mimic natural antibodies that the body generates to fight infection.
“Now, a study — ZRC3308 monoclonal antibody cocktail shows protective efficacy in Syrian hamsters against SARS-CoV-2 infection — posted as a recent pre print on the bioRxiv -(which is not peer reviewed) has found the cocktail to be cross neutralising, promising candidate for prophylactic use and for therapy in early cases which have not progressed to severe disease.
The decrease in viral load was found proportional to the high antibody concentrations,” study researchers have said.
Researchers used the Syrian hamster model to evaluate the protective efficacy of the mAb cocktail. Viral load reduction is used as a criteria to evaluate the effect of mAb in magnitude of infection in human clinical trials. There was a significant viral load reduction in the upper respiratory tract and lungs of infected hamsters. Study researchers said that the reduction in the viral load in the nasal wash in the mAB treated animals is important as the upper respiratory tract viral load is a key determinant of transmission. The study also evaluated the importance of timing of the mAB treatment.
Vaccines against SARS-CoV-2 infections have been rolled out as prophylactic interventions but the treatment options are still very limited. Monoclonal antibodies act like natural antibodies by binding and destroying SARS-CoV-2 spike protein.
Neutralising monoclonal antibody-based treatments have received emergency use authorisation in mild Covid-19 cases in the US, Europe and India because they significantly reduce viral load in mild patients and their rate of hospitalisation. There are now more than 200 research laboratories across the world that are working on developing highly potent recombinant human mAbs against SARS-CoV-2.