Safety and Efficacy Profile of Live, Intermediate Plus Vaccine Against Infectious Bursal Disease Based on Strain G6.

Infectious bursal disease (IBD) is an acute, highly contagious, immunosuppressive disease of young chickens that causes considerable economic loss in the poultry industry worldwide. Vaccination with live attenuated vaccines is still the most important method used for the control and prevention of IBD in chickens. Here we present the results of in vitro characterization, as well as efficacy and safety testing of a live, intermediate plus vaccine against IBD based on strain G6. Strain characterization confirmed that G6 strain is an intermediate plus strain, showing a high degree of homology with the existing vaccine strains of the same virulence. Safety studies showed that chickens can be vaccinated from 10 days of age. Onset and duration of immunity in specific pathogen free and maternally derived antibodies (MDA) chickens was proven to be 14 and 35 days after vaccination, respectively. When immunizing MDA-positive chickens, vaccine is capable of breakthrough at a titer of ≤500 ELISA units. The field trial conducted on commercial broilers showed a 95% protection against vvIBDV challenge. Stability of the freeze-dried vaccine after reconstitution was confirmed over a period of 3 h. Overall, IBD G6 vaccine has shown good safety and efficacy profile in accordance with European Pharmacopoeia requirements.

Efficacy of Infectious Bronchitis GI-13 (793B) Vaccine Candidate Tested According to the Current European Union Requirements and for Cross-Protection Against Heterologous QX-Like Challenge.

Infectious bronchitis (IB) is a highly contagious viral disease of chickens, known to cause severe economic losses. Vaccination against IB virus (IBV) is an important control measure against the disease. The objective of the present study was to test Avishield IB GI-13, the vaccine candidate against IBV, strain V-173/11 (GI-13 genotype), according to European Pharmacopoeia (Ph. Eur.) efficacy requirements. Laboratory study on specific-pathogen-free (SPF) chickens showed 100% protection against challenge 10 days after vaccination of 1-7 day-old chickens by three recommended routes. Duration of immunity was shown to be at least 8 weeks after vaccination. Chickens with maternally derived antibodies (MDA) were 100% protected against challenge 21 and 35 days after vaccination. Testing of the vaccine candidate in field conditions on commercial broiler and layer farms showed 80-90% protection against homologous challenge after spray (broilers and layers) or oral (broilers) vaccine administration. Serum antibodies were monitored during the studies, and although good seroconversion was observed in MDA-positive chickens 34 days after vaccination or later, the data from SPF chickens indicate that non-humoral immunity is important in protection against challenge. Neutralizing antibodies in tears were detected, however, their level could not be fully linked with individual protection scores. A cross-protection study showed that administration of the combination of Avishield IB H120 vaccine and Avishield IB GI-13 vaccine candidate at day 1, confers good protection against heterologous QX-like challenge. Stability of the vaccine after reconstitution in 0.2% skimmed milk solution or distilled water at room temperature was confirmed over the period of 3 h. The vaccine candidate fully complied with Ph. Eur. requirements, with very good protection levels, indicating that it can be administered already at 1 day of age by spray at the hatchery or at 7 days of age by drinking water on the farm.

Rapid transient expression of human granulocyte-macrophage colony-stimulating factor in two industrial cultivars of tobacco (Nicotiana tabacum L.) by agroinfiltration.

We report the production of hGM-CSF cytokine in leaves of industrial tobacco cultivars DH-17 and DH-27 by using Agrobacterium-mediated transient expression. We prove the concept that very high biomass industrial tobacco plants are suitable platforms for rapid, low cost production of foreign proteins. Successful transient expression of the GM-CSF was achieved in less than three months, opening the possibility for future applications of this approach in rapid response production of various proteins of non-plant origin in industrial tobacco.