A team of Brazilian researchers has found that antibody fragments produced in horses may be an efficient approach to combat Covid-19.

Researchers from the Federal University of Rio de Janeiro immunised horses using the recombinant trimeric spike (S) glycoprotein for the production of hyperimmune serum, consisting of purified antibody fragments, against SARS-CoV-2. After developing the horse hyperimmune F(ab’)2 concentrate, the group carried out challenge tests in hamsters, injecting the substance into the animals.

The results, published in the journal iScience, showed the ability of the treatment to reduce viral load in pulmonary tissues, and to improve the animal clinical conditions, as reflected by weight gain. All intervention schemes protected the animals against weight loss in the acute phase of the disease. Non-treated animals showed an increased weight loss, whereas pre-treatment resulted in no body weight reduction.

“By using the trimeric spike protein of SARS-CoV-2 to immunise horses, a cocktail of purified IgG fragments (F(ab’)2) showing very high neutralising activity was developed. This might be a useful countermeasure against Covid-19, with the added advantages of being an affordable alternative that can be produced in horse serum production facilities available worldwide,” said Professor Leda Castilho, from the Federal University of Rio de Janeiro.

The neutralising activity of the sera developed by the scientists has also been proved to be high against the P.1 (Gamma) and P.2 Covid variants, said researchers.

Meanwhile, iSera Biologicals, a Kolhapur-based company, is also using a similar technology for its Covid vaccine, according to media reports.

The company, which claims to cure Covid patients in just 90 hours, is developing the drug made from horse antibodies. Phase 1 clinical trials of the injectable drug against Covid-19 are underway in Maharashtra, and could be India’s first indigenously developed injectable drug that would be used to treat the viral infection.

The Pune-based Serum Institute of India (SII) has provided technology, antigens and chemicals that induce the production of antibodies. The antigens provided by SII were injected into horses, to develop antibodies, which were then extracted and purified using advanced chromatography technology.