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

Genomic sequence and phylogenetic analyses of two novel orthoreovirus strains isolated from Pekin ducks in 2014 in Germany

Complete genomic sequences of two orthoreovirus strains, D2533/4/1-10 and D2533/6/1-10, isolated from Pekin ducklings in Germany have been determined. Pairwise sequence comparisons and phylogenetic analyses indicated that strain D2533/4/1-10 might have acquired its genomic segments from three different origins, from classical and novel waterfowl reoviruses, and a yet unknown orthoreovirus strain. D2533/6/1-10 proved to be only distantly related to previously described orthoreoviruses. Reassortment, host species transmission events, and successful adaptation of novel variants may signify a challenge for animal health and maintenance of economic production

Survey indicates circulation of 4/91 and QX-type infectious bronchitis viruses in Hungary in 2014 — Short communication

Understanding the epidemiology and improving vaccinal protection against the highly variable chicken infectious bronchitis virus (IBV) requires the knowledge of circulating IBV serotypes/genotypes in defined geographic areas. Accordingly, the authors initiated a survey among the major poultry producers in Hungary in order to reveal the prevailing IBV serotypes in the country. Tracheal swabs and organ samples (caecal tonsils, kidneys, and trachea) were collected from broiler, layer, and meat-type breeder flocks, and were subjected to IBV detection by virus isolation and polymerase chain reaction (PCR). The IBV-positive samples were further characterised by nucleotide sequencing and phylogenetic analysis of a portion of the S1 IBV gene. Seventeen out of the 26 submitted samples proved to be positive for IBV. Sequence analyses revealed ten 4/91 and six QX serotypes, and a single D274 type IB virus. One sample contained a mixture of QX and Massachusetts serotype viruses. Presumably most of the 4/91 and D274 type viruses were vaccine strains. The proportion of QX type viruses and their observed variation are in good agreement with the situation in a few other European countries. The detected viruses clustered largely according to their geographic origin, with a few exceptions. If updated regularly, the preliminary ‘virus map’ will be useful for the adjustment of vaccination protocols

Genomic Epidemiology and Evolution of Duck Hepatitis A Virus

Duck hepatitis A virus (DHAV), an avian picornavirus, causes high-mortality acute disease in ducklings. Among the three serotypes, DHAV-1 is globally distributed, whereas DHAV-2 and DHAV-3 serotypes are chiefly restricted to Southeast Asia. In this study, we analyzed the genomic evolution of DHAV-1 strains using extant GenBank records and genomic sequences of 10 DHAV-1 strains originating from a large disease outbreak in 2004–2005, in Hungary. Recombination analysis revealed intragenotype recombination within DHAV-1 as well as intergenotype recombination events involving DHAV-1 and DHAV-3 strains. The intergenotype recombination occurred in the VP0 region. Diversifying selection seems to act at sites of certain genomic regions. Calculations estimated slightly lower rates of evolution of DHAV-1 (mean rates for individual protein coding regions, 5.6286 × 10−4 to 1.1147 × 10−3 substitutions per site per year) compared to other picornaviruses. The observed evolutionary mechanisms indicate that whole-genome-based analysis of DHAV strains is needed to better understand the emergence of novel strains and their geographical dispersal

Efficacy of a Turkey Herpesvirus Vectored Newcastle Disease Vaccine against Genotype VII.1.1 Virus: Challenge Route Affects Shedding Pattern

The control of Newcastle disease (ND) highly relies on vaccination. Immunity provided by a ND vaccine can be characterized by measuring the level of clinical protection and reduction in challenge virus shedding. The extent of shedding depends a lot on the characteristics of vaccine used and the quality of vaccination, but influenced also by the genotype of the challenge virus. We demonstrated that vaccination of SPF chicks with recombinant herpesvirus of turkey expressing the F-gene of genotype I ND virus (rHVT-ND) provided complete clinical protection against heterologous genotype VII.1.1 ND virus strain and reduced challenge virus shedding significantly. 100% of clinical protection was achieved already by 3 weeks of age, irrespective of the challenge route (intra-muscular or intra-nasal) and vaccination blocked cloacal shedding almost completely. Interestingly, oro-nasal shedding was different in the two challenge routes: less efficiently controlled following intra-nasal than intra-muscular challenge. Differences in the shedding pattern between the two challenge routes indicate that rHVT-ND vaccine induces strong systemic immunity, that is capable to control challenge virus dissemination in the body (no cloacal shedding), even when it is a heterologous strain, but less efficiently, although highly significantly (p < 0.001) suppresses the local replication of the challenge virus in the upper respiratory mucosa and consequent oro-nasal shedding

Immunogenic Cross-Reactivity between Goose and Muscovy Duck Parvoviruses: Evaluation of Cross-Protection Provided by Mono- or Bivalent Vaccine

To investigate the immunogenic cross reactivity between goose parvovirus (GPV) and Muscovy duck parvovirus (MDPV), cross-neutralization was carried out with serum samples collected from birds after infection with one of the two waterfowl parvoviruses. The significantly higher virus neutralization titer obtained against the homologous virus than against the heterologous one suggests important differences between the GPV and MDPV antigenic make up that affects the induced protective virus-neutralizing antibody specificity. This was further confirmed by cross-protection studies carried out in waterfowl parvovirus antibody-free Muscovy ducks immunized at one day of age with whole-virus inactivated oil-emulsion vaccines containing either GPV or MDPV as a monovalent vaccine, or both viruses as a bivalent vaccine. Protection against the clinical disease (growth retardation and feathering disorders) provided by the monovalent vaccine was complete against homologous virus challenge at 2 weeks post-vaccination, while the protection against the heterologous virus challenge was significantly lower (p < 0.001). Only the bivalent vaccine containing both goose and Muscovy duck parvoviruses in an inactivated form protected the birds (90–100%) against both waterfowl parvoviruses that can cause disease in Muscovy ducks. Both the cross-neutralization and cross-protection results indicated that adequate protection in Muscovy ducks against the two waterfowl parvoviruses could be achieved only with a vaccine containing both goose and Muscovy duck parvoviruses. Our results showed that the inactivated vaccine applied at one day of age could induce fast immunity (by 2 weeks post-vaccination), providing complete clinical protection in maternal antibody-free birds. It was also demonstrated that day-old vaccination of ducks with maternal antibodies with bivalent vaccine induced active immunity, resulting in 90 to 100% protection by 3 weeks of age, after the decline of maternal antibodies. A booster vaccination administered at 3 weeks of age following the day-old vaccination resulted in a strong and durable immunity against the clinical disease during the susceptible age of the birds