Oral administration of Saccharomyces cerevisiae displaying VP28-VP24 confers protection against white spot syndrome virus in shrimp

Effects of dietary supplementation of Anabaena sp. PCC7120 expressing VP28 protein on survival and histopathology after WSSV infection in Macrobrachium nipponense

Shrimp are especially susceptible to the White Spot Syndrome Virus (WSSV). Oral administration of the WSSV envelop protein VP28 is a promising approach to protect shrimp against WSSV. In this study, Macrobrachium nipponense (M. nipponense) were fed for 7 days with food supplemented with Anabaena sp. PCC 7120 (Ana7120) expressing VP28 and then challenged with WSSV. The survival rates of M. nipponense in three groups, including control, WSSV-challenged, and VP28-vaccinated, were subsequently determined. We also determined the WSSV content of different tissues and the tissue morphology in the absence of and after viral challenge. The survival rate of the positive control group (no vaccination and challenge, 10%) and empty vector group (fed with Ana7120 pRL-489 algae and challenged, 13.3%) was much lower than the survival rate of M. nipponense in wild type group (fed with Ana7120 and challenged, 18.9%), immunity group 1 (fed with 3.33% Ana7120 pRL-489-vp28 and challenged, 45.6%) or immunity group 2 (fed with 6.66% Ana7120 pRL-489-vp28 and challenged, 62.2%). RT-qPCR showed that WSSV content of the gill, hepatopancreas and muscle of immunity groups 1 and 2 were substantially lower than the positive control. Microscopic examination revealed that WSSV-challenged positive control exhibited large number of cell rupture, necrosis, nuclear exfoliation in gills and hepatopancreatic tissues. The gill and hepatopancreas of immunity group 1 showed partial symptoms of infection, yet the tissue was visibly healthier than that of the positive control group. No symptoms were visible in the gills and hepatopancreatic tissue of immunity group 2. The results demonstrate that the probability of M. nipponense infected by WSSV can be diminished by oral administration of cyanobacteria-expressed VP28. Such an approach could improve the disease resistance and delay the death of M. nipponense in the commercial production of this shrimp.

Yeast oral vaccines against infectious diseases

Vaccines that are delivered orally have several advantages over their counterparts that are administered via injection. Despite the advantages of oral delivery, however, approved oral vaccines are currently limited either to diseases that affect the gastrointestinal tract or to pathogens that have a crucial life cycle stage in the gut. Moreover, all of the approved oral vaccines for these diseases involve live-attenuated or inactivated pathogens. This mini-review summarizes the potential and challenges of yeast oral vaccine delivery systems for animal and human infectious diseases. These delivery systems utilize whole yeast recombinant cells that are consumed orally to transport candidate antigens to the immune system of the gut. This review begins with a discussion of the challenges associated with oral administration of vaccines and the distinct benefits offered by whole yeast delivery systems over other delivery systems. It then surveys the emerging yeast oral vaccines that have been developed over the past decade to combat animal and human diseases. In recent years, several candidate vaccines have emerged that can elicit the necessary immune response to provide significant protection against challenge by pathogen. They serve as proof of principle to show that yeast oral vaccines hold much promise.

Saccharomyces cerevisiae cell surface display technology: Strategies for improvement and applications

Microbial cell surface display technology provides a powerful platform for engineering proteins/peptides with enhanced properties. Compared to the classical intracellular and extracellular expression (secretion) systems, this technology avoids enzyme purification, substrate transport processes, and is an effective solution to enzyme instability. Saccharomyces cerevisiae is well suited to cell surface display as a common cell factory for the production of various fuels and chemicals, with the advantages of large cell size, being a Generally Regarded As Safe (GRAS) organism, and post-translational processing of secreted proteins. In this review, we describe various strategies for constructing modified S. cerevisiae using cell surface display technology and outline various applications of this technology in industrial processes, such as biofuels and chemical products, environmental pollution treatment, and immunization processes. The approaches for enhancing the efficiency of cell surface display are also discussed.