Titration of Marek's Disease Cell-Associated Vaccine Virus (CVI 988) of Reconstituted Vaccine and Vaccine Ampoules from Dutch Hatcheries

Landman, W. J. M.; Verschuren, S. B. E.

doi:10.1637/7034

Cited by 19 publications

(13 citation statements)

References 25 publications

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“…Dilution of vaccines to reduce vaccination cost is also a common practice within the broiler chicken industry. Administration of doses lower than the minimum protective dose (1000 PFU as per USA requirements) will have a negative impact not only on the protection against LTV but also against Marek's disease (Landman & Verschuren, 2003;Baigent et al, 2007;Gimeno et al, 2011). In the present study we did not evaluate replication of vaccines during the first week after vaccination, and therefore in vivo differences between rHVT-LT and HVT at early stages cannot be ruled out.…”

Section: Tissue Weekmentioning

confidence: 92%

Replication of recombinant herpesvirus of turkey expressing genes of infectious laryngotracheitis virus in specific pathogen free and broiler chickens followingin ovoand subcutaneous vaccination

et al. 2011

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Replication of a recombinant herpesvirus of turkey vaccine expressing infectious laryngotracheitis virus genes (rHVT-LT) was evaluated in specific pathogen free (SPF) and commercial broiler chickens after various vaccination protocols (amniotic route at embryonation day [ED] 18; intra-embryonic route at ED 19; and subcutaneous at 1 day of age [s.c.]). Three experiments were conducted: in the first experiment, replication of rHVT-LT vaccine was chronologically evaluated and compared with the replication of herpesvirus of turkey (HVT) in SPF chickens; in the second experiment, the effect of different in ovo vaccination procedures on rHVT-LT vaccine replication was evaluated in SPF chickens; and in the third experiment, the effect of different in ovo vaccination procedures on rHVT-LT vaccine replication was evaluated in commercial broiler chickens with maternal antibodies against HVT and infectious laryngotracheitis virus (LTV). rHVT-LT vaccine replicated in chickens after in ovo (ED 18 and ED 19) or s.c. administration at a similar level. In vivo replication of rHVT-LT vaccine was slower than HVT vaccine. However, in vivo both rHVT-LT and HVT vaccines replicated at similar levels. Both vaccines were consistently detected in the spleen and feather pulp and at lower frequency in the lung. The frequency of samples with detectable levels of rHVT-LT DNA was lower in broiler chickens than in SPF chickens, probably due to interactions with maternal antibodies. Differences between SPF chickens and broiler chickens were found also in the transcription of the LTV glycoprotein I gene (gI). In SPF chickens, in ovo inoculation resulted in a higher number of spleen samples with detectable gI transcripts than s.c. inoculation. In broiler chickens, however, no differences in the level of gI transcripts in spleen samples were found between chickens vaccinated in ovo and those vaccinated by the s.c. route. Transcription of LTV gI gene in lung samples was very low in both SPF and broiler chickens. Further studies to evaluate the mucosal immune response elicited by rHVT-LT in chicken with and without maternal antibodies are warranted.

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Section: Tissue Weekmentioning

confidence: 92%

Replication of recombinant herpesvirus of turkey expressing genes of infectious laryngotracheitis virus in specific pathogen free and broiler chickens followingin ovoand subcutaneous vaccination

et al. 2011

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“…However, vaccine breaks, excessive MD losses in a vaccinated flock, do occur and can have several causes: inhibition of vaccine virus replication by maternal antibodies (King et al, 1981;de Boer et al, 1986); suppression of the immune response to vaccine by environmental stresses or co-infections with immunosuppressive pathogens; infection with a virulent MDV strain prior to establishment of full vaccinal immunity; infection of vaccinated and fully immunocompetent birds with a highly virulent MDV able to break CVI988 immunity (Witter et al, 2005); and, finally, administration of insufficient vaccine dose that thus fails to induce protective immunity. The standard reference dose requirement for commercial CVI988 vaccine in Europe is ]1000 TCID 50 (which equates to approximately 1000 plaque-forming units (PFU), and has proved adequate in controlling disease), and in the USA it is 1500 PFU (Landman & Verschuren, 2003). However, improper storage, handling and reconstitution of vaccine stocks can mean that the actual amount administered to each chicken is lower than one standard dose.…”

Section: Introductionmentioning

confidence: 99%

“…This can be a significant cause of MD vaccine breaks, as recently seen in CVI988-vaccinated flocks in The Netherlands. During those outbreaks, plaqueforming assays on vaccine ampoules and reconstituted vaccine showed the average MD vaccine dose was frequently significantly below 1000 PFU and, in one hatchery, was lower than 10 PFU (Landman & Verschuren, 2003).…”

Section: Introductionmentioning

confidence: 99%

Correlation of Marek's disease herpesvirus vaccine virus genome load in feather tips with protection, using an experimental challenge model

Baigent

Smith

Currie³

et al. 2007

Avian Pathology

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We previously developed a real-time polymerase chain reaction (PCR) assay for absolute quantitation of serotype 1 Marek's disease virus in feather tips of chickens, and this has been used clinically to monitor a flock's response following vaccination with CVI988, an attenuated serotype 1 strain. The level of vaccine virus in feather tips associated with protection against challenge by virulent virus is not known. Here, we used an experimental challenge model, in which one dose of vaccine gives over 90% protection against mortality, to investigate correlation between the CVI988 level in feathers and protection. One-day-old chickens were vaccinated with 1, 0.1 or 0.01 commercial dose of CVI988 vaccine, and were then challenged with a virulent strain (RB-1B) 14, 21 or 28 days later. Replication of CVI988 virus was followed in each bird by real-time PCR analysis of feather DNA samples. Since the PCR does not differentiate between CVI988 and RB-1B, samples were taken only prior to challenge to ensure that the virus being measured was CVI988. Administration of one dose of vaccine ensured a uniform, rapid and high replication amongst birds, while replication following administration of the 0.1 or 0.01 dose was very variable. However, given time, a low early level of vaccine virus eventually replicated to high levels in some birds. Both the dose of vaccine virus administered and the level of vaccine virus in feather tips at 13 days post vaccination showed significant correlation with protection against challenge. A level of CVI988 vaccine virus of 132 genome copies/10000 feather tip cells was calculated to be the level required for 90% protection in this experimental model. The potential of this assay, and its limitations for monitoring protection in the field, are discussed.

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“…Em pesquisa sobre prevalência geral de doenças neoplásicas, concordando com o presente estudo, também se observou Doença de Marek em maior frequencia [28]. A Doença de Marek (DM) é uma doença neoplásica, de ampla disseminação na avicultura mundial e que causa imunossupressão nas aves, sendo alto prejuízo econômico com mortalidades, custo com vacinação, condenações com carcaça e queda na produção de ovos [15].…”

Section: Discussionunclassified

Risk Factors Associated with the Presence of Viral Diseases in Domestic Poultry in the Southern Region of Rio Grande do Sul, Brazil

Hirschmann

Fischer

Hübner

et al. 2019

Acta Scientiae. Vet.

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Background: The introduction of any infectious agent into an industrial or subsistence farm worries agribusiness owners in Brazil because it reduces product quality and increases treatment costs, although most diseases are untreatable, thus causing economic losses with morbidity and mortality. Therefore, an epidemiological survey of viral diseases associated with poultry was developed by performing a detailed description of the risk factors that may be related to existing diseases using domestic poultry sample data recorded in the Regional Diagnostic Laboratory (LRD) of College of Veterinary Medicine of the Federal University of Pelotas (UFPel), Rio Grande do Sul, Brazil, from 2000 to 2016.Materials, Methods & Results: Epidemiological and clinical-pathological data were collected and then compared with disease data by multivariate analysis using statistical EpiInfo version 6.04 and Microsoft Office Excel 2010 software. The frequencies and 95% confidence intervals (CI), association measures (odds ratio=OR and relative risk=RR), Chi-square test, and the results considered significant with a value of P ≤ 0.05 were described. A total of 410 samples of domestic poultry were tested, and the results showed 66 (16.1%) viral diseases. The following conditions were the most commonly found diseases in this study: Marek’s disease (42.4%), Infectious bursal disease (31.8%), Avian leukosis (16.6%), Avian pox (7.5%) and Avian infectious bronchitis (1.5%). In this article we discuss the most frequent viral diseases: Marek’s disease (DM) and Gumboro disease. It was also possible to conclude that birds with Marek's disease presented higher odds of developing nerve, tegumentary and locomotors signs (P ≤ 0.05). As well as, more likely to present tumoriform lesions in the liver, spleen, kidneys and heart P ≤ 0.05, as well as lesions in the proventriculus, muscle lesions and in the sciatic nerve P ≤ 0.05. Laying poultry, backyard poultry production and young poultry constitute risk factors for DM (P ≤ 0.05). The results showed that samples with mycotoxicoses were at higher risk of developing DM (P ≤ 0.05). Poultry from industrial system had a higher risk of developing Gumboro disease (P ≤ 0.05). Besides that, domestic poultry with Gumboro disease were more likely to develop signs of depression, nerve signals, tegumentary changes, bursitis, hepatomegaly, renal lesions and splenomegaly (P ≤ 0.05).Discussion: In this research we can observe the domestic poultry with DM presenting tumoriform lesions in several organs, this finding is common in this disease, because it is one of the most frequent viral diseases of neoplastic characteristic. The results show that young birds are a risk factor for DM. In fact, previous works already affirm young birds as being susceptible to disease in relation to adult birds. In this study, laying hens presented a risk factor for DM, however other authors also observed in cut birds or in both types of production. Industrial poultry are at higher risk for DM, this was also reported by other authors, because the disease is of high contagion and morbidity, industrial birds are under high density which facilitates the contact and dissemination of the virus among sick and susceptible birds. In this study, industrial poultry were a risk factor for Gumboro disease, however, other studies show that there is no difference between types of breeding and can also occur in backyard birds. Young poultry and laying hens are more susceptible, and the clinical signs found in the study are compatible with those described in the literature. Through this research on viral diseases, we conclude that our study may complement the already existing official data, since, in a research conducted in the same period, it did not identify the presence of viral diseases in the Southern of RS, but with our research it was possible to register this disease.

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Titration of Marek's Disease Cell-Associated Vaccine Virus (CVI 988) of Reconstituted Vaccine and Vaccine Ampoules from Dutch Hatcheries

Cited by 19 publications

References 25 publications

Replication of recombinant herpesvirus of turkey expressing genes of infectious laryngotracheitis virus in specific pathogen free and broiler chickens followingin ovoand subcutaneous vaccination

Replication of recombinant herpesvirus of turkey expressing genes of infectious laryngotracheitis virus in specific pathogen free and broiler chickens followingin ovoand subcutaneous vaccination

Correlation of Marek's disease herpesvirus vaccine virus genome load in feather tips with protection, using an experimental challenge model

Risk Factors Associated with the Presence of Viral Diseases in Domestic Poultry in the Southern Region of Rio Grande do Sul, Brazil

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