Engineering Sorghum for Developing an Oral Veterinary Vaccine against Anthrax

Abstract

Dimpal Mehla1, Nishant Bhandhari1, Hemant Joshi2, Sandeep Yadav1, Rakesh Bhatnagar2 and Manoj K Sharma1

1Crop Genetics & Informatics Group, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India 110067

2Laboratory of Molecular Biology and Genetic Engineering, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India, 110067.

Anthrax is an infectious zoonotic disease that primarily affects herbivorous animals like sheep, goats, cattle etc. and can spread to human too. It is caused by a spore-forming gram-positive bacterium Bacillus anthracis. It is of particular importance due to frequent natural outbreaks in domestic/wild animals and could be transferred to humans too. Because, it is easy to weaponize and disseminate it in the form of invisible aerosol, and therefore it could be a potential bio-warfare agent. Modern genetic tools have opened new ways to make vaccines and plant-based expression systems are showing great promise as these are safe, affordable and easy to scale-up. Protective antigen (PA) from Bacillus anthracis or its domain IV provides complete protection against anthrax spore challenge and is the key component of vaccines. For developing a animal friendly anthrax vaccine, we have transferred the genes encoding for the PA or domain IV of PA to the fodder plant sorghum, using Agrobacterium. To boost the immune responses, non-toxic cholera toxin B subunit is used as an adjuvant that induces Th17- mediated responses critical for host defence and stabilize the vaccine within the digestive system. We have introduced the gene encoding for the cholera toxin B subunit as a fusion partner with domain IV encoding gene in sorghum. Testing showed that transgenic plants successfully produced the antigen proteins maintaining their immunogenic confirmation.

Immunological profiling in the model organism through oral immunization, it triggered high level of protective antibodies i.e. IgG and IgA, thereby thereby confirming the feasibility of plant based oral vaccine against anthrax.