News Excerpt:

According to a 2020 world health organisation report, the mortality burden is especially higher in low and middle-income countries in Africa and Asia, with India alone at a staggering average of 58,000 deaths in a year.

• Venom from snake bites leads to more than 100,000 deaths every year, with around 400,000 people left permanently disabled.

Various types of venoms:

• Venoms of snakes in India are so diverse that the same antivenom can’t neutralise venoms of the same species across regions.
• Even in the same geographical location, antivenom can only neutralise some venoms and not others.

Screening billions of antibodies:

• The scientists focused on three-finger toxins (3FTxs) — one of the most abundant and lethal ingredients in elapid venoms. 
• Elapids are a major medically relevant family of snakes that include cobras, kraits, and mambas.
• The scientists narrowed their focus on α-neurotoxins, a class of 3FTxs that target human nerve and muscle cell receptors. 
• These toxins prevent the receptors from responding to acetylcholine, a neurotransmitter involved in carrying messages from the neurons to the muscles, leading to paralysis, an inability to breathe, and eventually death.
• Scientists tested the antibodies in vitro in human cells to see which of them could best neutralise the toxins. This step brought them to an antibody they dubbed 95Mat5.
• They tested 95Mat5 in vivo in mice to see if this broadly neutralising antibody could help protect against lethal doses of α-bungarotoxin, the 3FTx-L in the highly venomous many-banded kraits.
• They found 95Mat5 worked well against all the snake venoms, with the only exception being the king cobras’ venom, where the antibody delayed but could not prevent death.

Universal solution:

• In the current study, the scientists found one reason why their antibody worked so well against their toxins of interest. 
• The crystal structures of their antibody 96Mat5 and 3FTx-L variants revealed that the antibody bound the toxin exactly where it would have bound its target receptor in human nerve and muscle cells. 
• By mimicking the receptor-toxin interaction, the antibody could whisk the toxins away from the receptors and prevent them from exerting their deadly effects.
• The current antibody works well against a specific kind of toxin present in the venom of many dangerous snakes. Still, it is a small first step towards a universal antivenom. 
• The scientists said they are keen on discovering specific antibodies like these against toxins in other snake venoms as well, like in vipers.