Development of Vaccines for Poultry Against H5 Avian Influenza Based on Turkey Herpesvirus Vector

Avian influenza (AI) remains a major threat to public health as well as to the poultry industry. AI vaccines are considered a suitable tool to support AI control programs in combination with other control measures such as good biosecurity and monitoring programs. We constructed recombinant turkey herpesvirus (HVT) vector vaccines expressing the hemagglutinin gene of AI virus H5 subtype (rHVT‐H5) and evaluated their characteristics and efficacy against AI. We found that the cytomegalovirus (CMV) promoter is the most suitable for expression of the hemagglutinin gene among three promoters we evaluated. The rHVT‐H5 vaccine did not cause any adverse reactions and did not revert to virulence after passages in chicken. Finally, efficacy of the rHVT‐H5 vaccine was evaluated. We demonstrated that it provided protection against diverse AI H5 viruses belonging to different clades and reduced virus shedding from the challenged chicken. We also proved that efficacy provided by the rHVT‐H5 vaccine was not significantly affected by presence of maternally derived antibodies (MDA) against AI virus. Furthermore, the rHVT‐H5 vaccine could be applicable to the differentiating infected from vaccinated animals (DIVA) strategy. In summary, we successfully developed a HVT vector AI vaccine that possesses features that could be beneficial to AI control

Recombination Events Shape the Genomic Evolution of Infectious Bronchitis Virus in Europe

Infectious bronchitis of chicken is a high morbidity and mortality viral disease affecting the poultry industry worldwide; therefore, a better understanding of this pathogen is of utmost importance. The primary aim of this study was to obtain a deeper insight into the genomic diversity of field infectious bronchitis virus (IBV) strains using phylogenetic and recombination analysis. We sequenced the genome of 20 randomly selected strains from seven European countries. After sequencing, we created a genome sequence data set that contained 36 European origin field isolates and 33 vaccine strains. When analyzing these 69 IBV genome sequences, we identified 215 recombination events highlighting that some strains had multiple recombination breaking points. Recombination hot spots were identified mostly in the regions coding for non-structural proteins, and multiple recombination hot spots were identified in the nsp2, nsp3, nsp8, and nsp12 coding regions. Recombination occurred among different IBV genotypes and involved both field and vaccine IBV strains. Ninety percent of field strains and nearly half of vaccine strains showed evidence of recombination. Despite the low number and the scattered geographical and temporal origin of whole-genome sequence data collected from European Gammacoronaviruses, this study underlines the importance of recombination as a major evolutionary mechanism of IBVs

Genome sequences of three turkey orthoreovirus strains isolated in Hungary

We have investigated the genomic properties of three turkey reovirus strains—19831M09, D1246, and D1104—isolated in Hungary in 2009. Sequence identity values and phylogenetic calculations indicated genetic conservativeness among the studied Hungarian strains and a close relationship with strains isolated in the United States

Pathological and immunological study of an in ovo complex vaccine against infectious bursal disease

The appearance of very virulent strains of infectious bursal disease (IBD) virus at the end of the 1980s made it necessary to develop more effective immunization procedures. To facilitate this, the immunogenicity and the immunosuppressive effect of a mild (G-87), an intermediate (LIBD) and an intermediate-plus (IBDV 2512) IBDV strain were tested after the in ovo inoculation of 18-day-old SPF and broiler chicken embryos. It was established that no noteworthy difference existed between the immunized and the control embryos in hatching rate and hatching weight. The higher the virulence of the vaccine virus strain, the more severe damage it caused to the lymphocytes of the bursa of Fabricius. In SPF chickens, the haemagglutination inhibition (HI) titres induced by a Newcastle disease (ND) vaccine administered at day old decreased in inverse ratio to the virulence of the IBD vaccine strain, while in broiler chickens this was not observed. Despite the decrease of the HI titre, the level of protection did not decline, or did so only after the use of the ‘hot’ strain. SPF chickens immunized in ovo with a complex vaccine prepared from strain IBDV 2512 and IBD antibody showed the same protection against Newcastle disease as the broilers. In broiler chicken embryos immunized in ovo, only strain IBDV 2512 induced antibody production, and such chickens were protected against IBD at 3 weeks of age. The complex vaccine administered in ovo has been used successfully at farm hatcheries as well