The complexity of the interpretation of ELISA and RT-PCR results in the diagnosis of a reticuloendotheliosis virus infection: an extended case study.

Reticuloendotheliosis virus (REV) is a species of the genus that can cause neoplasia, immunosuppression, and runting-stunting syndrome. To show the clinical relevance of REV is complicated, and requires the demonstration of the virus, REV antibodies, the presence of typical gross and microscopic lesions, and the exclusion of other oncogenic agents in the case of the presence of tumours. Under field conditions, the first tests to be used might be a commercially available REV antibody ELISA or an RT-PCR to detect the REV genome.

The combination of infectious bronchitis virus BR1 and Mass vaccines provides broad protection.

Two vaccination-challenge trials were performed using a commercial infectious bronchitis virus (IBV) BR1 vaccine, given alone or combined with a commercial IBV Mass vaccine against challenges with IBV M41, 793B, D388 (QX), Q1, Brasil-1 or Variant 2 challenge viruses, which includes the IB viruses that are dominant in South America. The efficacy of the vaccines against the challenge viruses was investigated by determination of the ciliary activity of the tracheal epithelium after challenge. The level of protection induced by the IBV BR1 vaccine alone against the six IBV challenge strains, of which five were of heterologous genotypes, varied from 50% to 100% with an average of 80%.

Epidemiology-driven approaches to surveillance in HPAI-vaccinated poultry flocks aiming to demonstrate freedom from circulating HPAIV.

Incursion pressure of high pathogenicity avian influenza viruses (HPAIV) by secondary spread among poultry holdings and/or from infected migratory wild bird populations increases worldwide. Vaccination as an additional layer of protection of poultry holdings using appropriately matched vaccines aims at reducing clinical sequelae of HPAIV infection, disrupting HPAIV transmission, curtailing economic losses and animal welfare problems and cutting exposure risks of zoonotic HPAIV at the avian-human interface. Products derived from HPAIV-vaccinated poultry should not impose any risk of virus spread or exposure.

Molecular characterization of the gene of and the proposition of a new genotyping method as alternative for classical serotyping.

is the aetiological agent of infectious coryza (IC) in chickens and characterized by acute respiratory distress and severe drop in egg production. Vaccination is important in the control of IC outbreaks and the efficacy of vaccination is dependent on serovars included in the vaccine. Classical serotyping of is laborious and hampered by poor availability of antigens and antisera.

High specificity of the Pullorum/Gallinarum rapid plate agglutination test despite vaccinations against Enteritidis and Typhimurium.

In Europe, monitoring of breeding stock for Pullorum (SP) or a Gallinarum (SG) infections is compulsory at the point of lay. Vaccinations against Enteritidis (SE) and Typhimurium (ST) are increasingly administered in Europe. These vaccines might induce cross-reactions in the rapid plate agglutination (RPA) SP/SG test due to shared O-antigens, possibly resulting in a lower test specificity.

Identification, HPG2 Sequence Analysis, and Antimicrobial Susceptibility of Isolates Obtained from Outbreaks of Infectious Coryza in Commercial Layers in Sonora State, Mexico.

This is the first extensive report on the identification and characterization of (AVP) isolates obtained from outbreaks of infectious coryza (IC) in IC-vaccinated layer flocks from Sonora State in Mexico. Isolates obtained from IC outbreaks during the years 2007, 2014, 2015, 2017, and 2019 were identified by conventional PCR test and 16S rRNA gene analysis, serotyped by Page serotyping and genotyped by the recently described partial sequence analysis of the HPG2 region. Furthermore, antimicrobial susceptibility profiles were determined by a recently improved minimal inhibitory concentration (MIC) test.

Clinical expression, epidemiology, and monitoring of and : an update.

(MG) and (MS) are of clinical and economic importance for the global poultry industry. Many countries and integrations are involved in monitoring programmes to control both mycoplasma species. This review provides an extensive historic overview of the last seven decades on the development of the knowledge regarding the factors that influence the clinical expression of the disease, the epidemiology, and monitoring of both MG and MS.

Effect of IBV D1466 on egg production and egg quality and the effect of heterologous priming to increase the efficacy of an inactivated IBV vaccine.

To protect layers, breeders and grandparents against damage by infectious bronchitis virus infections during the laying period, vaccination using live priming followed by a boost with inactivated IB vaccine is commonly used. For many IB variants, homologous live vaccines are not available for priming. Very little is known about the efficacy of priming with heterologous live IB vaccines (or combination of live IB vaccines) to induce broad IB protection in long-living chickens.

Rate of false positive reactions in 11 and serological tests in samples obtained from SPF birds inoculated with heterologous mycoplasma species.

No recent information is available on the specificity of current (Ms) and (Mg) serological tests. In this study the performance of a currently available Mg and Ms Rapid Plate Agglutination (RPA) test, and three Mg, three Ms and three Mg/Ms combination ELISAs were evaluated on SPF sera that were obtained from days (D) 0-28 after , or inoculation, after sham inoculation and without inoculation. Tracheal swabs for mycoplasma culture were obtained before inoculation (D0), 7 and 28 days post inoculation (d.

Identification and characterization of Dutch isolates and the implications for diagnostics.

This study reports the results of diagnostic and molecular typing methods for 18 isolates obtained from outbreaks of infectious coryza in commercial layer flocks in the Netherlands. Isolation, biochemical identification, species-specific PCR tests and classical serotyping were performed. In addition, molecular typing by Enterobacterial Repetitive Intergenic Consensus-Based Polymerase Chain Reaction (ERIC-PCR) and sequence analysis of the partial HPG2 region of were applied and results of both techniques were compared.

Recombinant Infectious Bronchitis Viruses Expressing Chimeric Spike Glycoproteins Induce Partial Protective Immunity against Homologous Challenge despite Limited Replication .

Vaccination regimes against (IBV), which are based on a single virus serotype, often induce insufficient levels of cross-protection against serotypes and two or more antigenically diverse vaccines are used in attempt to provide broader protection. Amino acid differences in the surface protein, spike (S), in particular the S1 subunit, are associated with poor cross-protection. Here, homologous vaccination trials with recombinant IBVs (rIBVs), based on the apathogenic strain, BeauR, were conducted to elucidate the role of S1 in protection.

A proposed nomenclature for infectious bursal disease virus isolates.

Infectious bursal disease virus (IBDV) was initially identified in the USA. For decades, these viruses were not categorized using a typing system because they were considered to be antigenically and pathogenically similar. In the 1980s, a second major serotype, serotype 2, was found in turkeys.

Alternative methods to compare safety of live-attenuated respiratory Newcastle disease vaccines in young chicks.

The work reported here is an initial attempt to find an alternative method by which the safety of live-attenuated Newcastle disease virus (NDV) vaccines for the respiratory tract of young chickens can be assessed. The current recommended methods involve either the subjective assessment of respiratory signs, or raise ethical concerns, as in the case of the intracerebral pathogenicity index. The two methods considered here were the use of tracheal organ cultures to assess the level of ciliostasis which the vaccines caused to the ciliated epithelium of the trachea and the incorporation of a pathogenic strain of in the inoculum in order to induce colibacillosis.

Risk for Low Pathogenicity Avian Influenza Virus on Poultry Farms, the Netherlands, 2007-2013.

Using annual serologic surveillance data from all poultry farms in the Netherlands during 2007-2013, we quantified the risk for the introduction of low pathogenicity avian influenza virus (LPAIV) in different types of poultry production farms and putative spatial-environmental risk factors: distance from poultry farms to clay soil, waterways, and wild waterfowl areas. Outdoor-layer, turkey (meat and breeder), and duck (meat and breeder) farms had a significantly higher risk for LPAIV introduction than did indoor-layer farms. Except for outdoor-layer, all poultry types (i.

Experimental and Field Results Regarding Immunity Induced by a Recombinant Turkey Herpesvirus H5 Vector Vaccine Against H5N1 and Other H5 Highly Pathogenic Avian Influenza Virus Challenges.

Vaccination against H5N1 highly pathogenic avian influenza (AI) virus (HPAIV) is one of the possible complementary means available for affected countries to control AI when the disease has become, or with a high risk of becoming, endemic. Efficacy of the vaccination against AI relies essentially, but not exclusively, on the capacity of the vaccine to induce immunity against the targeted virus (which is prone to undergo antigenic variations), as well as its capacity to overcome interference with maternal immunity transmitted by immunized breeding hens to their progeny. This property of the vaccine is a prerequisite for its administration at the hatchery, which assures higher and more reliable vaccine coverage of the populations than vaccination at the farm.

Getting more out of less--a quantitative serological screening tool for simultaneous detection of multiple influenza A hemagglutinin-types in chickens.

Current avian influenza surveillance in poultry primarily targets subtypes of interest for the veterinary sector (H5, H7). However, as virological and serological evidence suggest, surveillance of additional subtypes is important for public health as well as for the poultry industry. Therefore, we developed a protein microarray enabling simultaneous identification of antibodies directed against different HA-types of influenza A viruses in chickens.

Assessment of impact of a novel infectious bursal disease (IBD) vaccination programme in breeders on IBD humoral antibody levels through the laying period.

Objectives: The purpose of this study was to assess whether broiler breeders vaccinated in ovo with a Vaxxitek (HVT&IBD) (Merial) plus an inactivated IBD vaccine prior to the onset of lay had a significantly different humoral IBD antibody response to broiler breeders vaccinated solely with Vaxxitek (HVT&IBD) (Merial) in ovo. In addition, maternally derived antibody (MDA) passed to the progeny of these two breeders flocks was also compared at three time points during lay.

Design: The study was a case-control study where the two flocks were the same breed, reared on the same farm and transferred to the same laying farm, the only difference between the flocks being the IBD vaccination programme.

Rate of introduction of a low pathogenic avian influenza virus infection in different poultry production sectors in the Netherlands.

Background: Targeted risk-based surveillance of poultry types (PT) with different risks of introduction of low pathogenic avian influenza virus (LPAIv) infection may improve the sensitivity of surveillance.

Objective: To quantify the rate of introduction of LPAIv infections in different PT.

Methods: Data from the Dutch LPAIv surveillance programme (2007-2010) were analysed using a generalised linear mixed and spatial model.

Infectious bronchitis virus variants: a review of the history, current situation and control measures.

The history, current situation and control measures for infectious bronchitis virus (IBV) variants are reviewed. A large number of IBV variants exist worldwide; some being unique to a particular area, others having a more general distribution. The possible reasons why some strains spread readily over major parts of the world, whereas other strains stay more localized are discussed.

Identification of new populations of chicken natural killer (NK) cells.

Natural killer (NK) cell activity is conserved throughout vertebrate development, but characterization of non-mammalian NK-cells has been hampered by the absence of specific mAbs for these cells. Monoclonal antibodies were generated against in vitro IL-2 expanded sorted CD3-CD8alpha+ peripheral blood lymphocytes, previously described to contain chicken NK-cells. Screening of embryonic and adult splenocytes with hybridoma supernatants resulted in five candidate NK markers.

A field study on the significance of vaccination against infectious bursal disease virus (IBDV) at the optimal time point in broiler flocks with maternally derived IBDV antibodies.

The right strategy for infectious bursal disease (IBD) control and its success rate under field conditions depends on hygiene management, IBD field pressure, level and variation in maternally derived IBD antibodies, and the IBD vaccine strains to be used. Usually, standard vaccination programmes are used, which are not always adapted to the specific conditions on the farm and to the immune status of chickens. Employing the "Deventer formula" may help to estimate the optimal time for vaccination for a specific flock based on the maternally derived antibody level, its variation, the genetic background of the chicken, and the IBD vaccine strain.