Page 90 - AWSAR 2.0

66 || AWSAR Awarded Popular Science Stories - 2019
neutralization of microbial toxins either as a stand-alone therapy or in combination with the existing antibiotics. Similarly, India also reports the highest number of cases of snakebites worldwide that are treated with an age- old strategy using anti-venom derived from horses immunized with snake venom. This treatment not only has a low potency but also frequently causes life-threatening side effects due to the foreign nature of horse antibodies. Such challenges can be addressed using recombinant human antibodies as they can beasaferandsuperioralternativetoexisting remedies and will drive the country towards realizing the vision of Hon’ble Prime Minister for a ‘Swasth’ Bharat. In fact, in India, a fully human monoclonal antibody m102.4, which is highly potent in neutralizing Nipah and Hendra viruses, was sourced by the Indian Council of Medical Research from Australia to treat the patients during Nipah outbreak in Kerala, India, in May 2018.
In this context, our team
at the Centre for Innovation in
Infectious Disease Research,
Education and Training
(CIIDRET), University of Delhi
South Campus (UDSC) has
developed an indigenous phage-displayed naïve human
antibody library constituting
10 billion different antibody
binders. This is a universal
library encoding the well-
characterized antibody
repertoire of naïve individuals
who are minimally exposed
to the disease-causing
pathogens. Hence, it is not
biased towards any particular
target. The library has been
constructed using a proprietary
PCR technology that eliminates
any chimerization between similar antibody
sequences during PCR-based gene amplification (Indian Patent 320566). The antibody genes have been cloned seamlessly into a highly optimized phage display vector using a restriction enzyme-free cloning strategy, integrated with protocols to obtain up to 109 transformants from 1 μg DNA, which is 10- to 20-folds more efficient than the usually obtained numbers. Nearly 100% of the clones in the library encode full-length antibody sequences with 70% clones encoding ‘in- frame’ antibody sequences. The antibody sequences show a high similarity to the unmutated antibody sequences present in the human germline, indicating their naïve-ness. The analysis of the library using large-scale sequencing (next-generation sequencing) has revealed that the library is highly diverse and contains billions of different antibody sequences the same as the human body. The antibody gene representation is also in
concordance with natural gene usage in humans. This library has successfully yielded a large number of different yet highly specific antibody binders against six proteins of M. tuberculosis. Most importantly, the library has yielded both exclusive and common binders against the two very similar proteins (>80% identity at the amino acid level). This finding shows that just like a human body, the antibody repertoire in the CIIDRET-UDSC library is so diverse that it can yield specific antibodies against proteins that only differ by a few amino acids. In collaboration with industry, the CIIDRET-UDSC library has been successfully used to obtain highly specific
binders against a human target of therapeutic
India also reports the highest number of cases of snakebites worldwide that are treated with an age-old strategy using anti-venom derived from horses immunized with snake venom. This treatment not only has a low potency but also frequently causes life-threatening side effects due to the foreign nature of horse antibodies. Such challenges can be addressed using recombinant human antibodies as they can be a safer and superior alternative to existing remedies