Comparison of Blood and Feather Pulp Samples for the Diagnosis of Marek's Disease and for Monitoring Marek's Disease Vaccination by Real Time-PCR

Cortes, Aneg L.; Montiel, Enrique; Lemière, Stéphane; Gimeno, Isabel M.

doi:10.1637/9724-957811-digest.1

Cited by 4 publications

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“…Viral DNA load was measured by real-time PCR and results were calculated based on the C t ratio (see Materials and Methods for further details). Chickens were classified based on the C t ratio into three categories*negative, latently infected(lat), and bearing tumours(tum)*based on results obtained in previous work (Cortes et al, 2011 have tried to develop a vaccine that exceeded the protection conferred by strain CVI988 but most efforts have not been successful (reviewed in Gimeno, 2008). Recently, several vaccine strains have been developed that seem to protect better than CVI988 against early challenge with vv'MDV Lee et al, 2008).…”

Section: Discussionmentioning

confidence: 99%

“…In previous studies, we have evaluated the load of challenge MDV DNA as an early diagnostic criterion for MD , Gimeno et al, 2011Cortes et al, 2011). We have demonstrated that, very early after infection, chickens could be classified into three categories based on the load of viral DNA (negative, latency, and tumours) (Cortes et al, 2011;Gimeno et al, 2011).…”

Section: Discussionmentioning

confidence: 99%

“…We have demonstrated that, very early after infection, chickens could be classified into three categories based on the load of viral DNA (negative, latency, and tumours) (Cortes et al, 2011;Gimeno et al, 2011). In the present study, we have evaluated the load of challenge viral DNA in chickens receiving single vaccination (HVT at 18ED, HVT ' SB(1 at 1 day, HVT ' SB(1 at 18ED) or double vaccination (HVT at 18ED and HVT ' SB(1 at 1 day).…”

Section: Discussionmentioning

confidence: 99%

“…Laboratory model to study MD revaccination 61 threshold line between latency and tumour in FP samples using this real-time PCR protocol has been calculated in previous studies (Gimeno et al, 2005;Cortes et al, 2009Cortes et al, , 2011. Data were analysed with the statistical program Statistica (Stat Soft, Tulsa, Oklahoma, USA).…”

Section: Methodsmentioning

confidence: 99%

“…Chickens were classified based on the C t ratio into three categories*negative, latently infected(lat), and bearing tumours(tum)*based on results obtained in previous work (Cortes et al, 2011). Experiment 8 was conducted in two replicates and results are presented together.…”

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confidence: 99%

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Standardization of a model to study revaccination against Marek's disease under laboratory conditions

Gimeno

Witter²,

Cortes

et al. 2012

Avian Pathology

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Revaccination, the practice of administering Marek's disease (MD) vaccine a second time, has been used in commercial poultry flocks for many years. The rationale is largely anecdotal as the few published reports have failed to provide support for the value of the practice. In the present work, we have standardized a model to study MD revaccination under laboratory conditions. Nine bird experiments were conducted to evaluate homologous revaccination (same vaccine administered twice) and heterologous revaccination (administration of two different vaccines) with various challenge models. Our results demonstrated that heterologous revaccination (with a second vaccine more protective than the first vaccine) but not homologous revaccination provided a beneficial increase in protection. Administration of the first vaccine at 18 days of embryonation followed by a more protective second vaccine at hatch reproduced systematically the benefits of revaccination. In addition, our results show that revaccination protocols might aid in solving major drawbacks associated with various highly protective experimental MD vaccines; that is, lymphoid organ atrophy and residual virulence. Strain RM1 is one of the most protective vaccines against early challenge with highly virulent MD virus but it induces severe lymphoid atrophy in chickens lacking maternal antibodies against MD virus. In this study, strain RM1 did not induce lymphoid organ atrophy when administered as second vaccine in a revaccination protocol. Similarly, strain 648A100/BP5 maintains residual virulence in chickens lacking maternal antibodies against MD virus but did not induce any lesions when used as a second vaccine. Until now, arbitrary revaccination protocols have been occasionally proven useful to the poultry industry. The model developed in this study will allow for a better understanding of this phenomenon and its optimization. A more rational use of this practice will be of great help to control MD outbreaks until better vaccines are available.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Standardization of a model to study revaccination against Marek's disease under laboratory conditions

Gimeno

Witter²,

Cortes

et al. 2012

Avian Pathology

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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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Quantification of rHVT-F genome load in feather follicles by specific real-time qPCR as an indicator of NDV-specific humoral immunity induced by day-old vaccination in SPF chickens

et al. 2015

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Comparison of Blood and Feather Pulp Samples for the Diagnosis of Marek's Disease and for Monitoring Marek's Disease Vaccination by Real Time-PCR

Cited by 4 publications

References 0 publications

Standardization of a model to study revaccination against Marek's disease under laboratory conditions

Standardization of a model to study revaccination against Marek's disease under laboratory conditions

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

Quantification of rHVT-F genome load in feather follicles by specific real-time qPCR as an indicator of NDV-specific humoral immunity induced by day-old vaccination in SPF chickens

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