SUMMARY
Vaccine plays a very important role in human and domestic animal life for combating infectious diseases. Existing and traditional methods of manufacturing vaccines in bulk to the required level of purity and quality are stretched to capacity and will soon become limiting in vaccine manufacturing. Moreover, traditional method of vaccine production is very expensive and is currently unaffordable by majority of the consumers. Plant-made vaccines (PMVs), on the other hand, offers unique opportunities to reduce cost significantly due to minimal investment requirement, ease and economy of scale-up, lack of risk of contamination with human pathogens, etc. There is a substantial and increasing worldwide demand for vaccines. Specialized plant-based gene-expression technologies are ready to provide an alternative manufacturing platform that can help meet the demand and thus overcome the perceived ?bottleneck? in vaccine production; and taken together, these situations make a strong case for commercial development of PMVs. A particularly attractive feature of the PMV is its potential to provide opportunities for both the agricultural sector and the biotechnology business sector simultaneously. Several Plant Biotechnology companies are already actively working in this area and worldwide many PMVs are at different stages of discovery through human clinical trials. PMV is currently an exciting and expanding area of plant biotechnology with great potentials to offer affordable vaccines to underprivileged population of the world. A large variety of host plants and expression systems have already been developed to deliver PMVs. However, there are concerns of low transgene expression, transgene escape, dose optimization and need for minor processing before oral delivery. The current status of achievements, challenges and opportunities will be covered in this review.