Effect of Diluting Marek's Disease Vaccines on the Outcomes of Marek's Disease Virus Infection When Challenged with Highly Virulent Marek's Disease Viruses

Gimeno, Isabel M.; Cortes, Aneg L.; Montiel, Enrique; Lemière, Stéphane; Pandiri, Arun K. R.

doi:10.1637/9736-957911-digest.1

Cited by 5 publications

(13 citation statements)

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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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“…Over diluting MD vaccines is a common practice within the broiler chicken industry to reduce cost and it negatively impacts the vaccine dose that chickens receive. Over-dilution of vaccines has been shown to reduce protection against MD as well as lowering relative body weights [116]. The extent of the negative effect of overdiluting vaccines depended on the vaccine used, the challenged virus, and the sex of the chickens, females being more susceptible than males [116].…”

Section: Vaccination Failures and Factors Influencing MD Outbreaksmentioning

confidence: 99%

“…Over-dilution of vaccines has been shown to reduce protection against MD as well as lowering relative body weights [116]. The extent of the negative effect of overdiluting vaccines depended on the vaccine used, the challenged virus, and the sex of the chickens, females being more susceptible than males [116]. Other practices, such as adding antibiotics to the reconstituted MD vaccines can affect negatively the dose and should be discouraged [217,218].…”

Section: Vaccination Failures and Factors Influencing MD Outbreaksmentioning

confidence: 99%

“…The virus content assay and the titer used in the efficacy study will determine the recommended dose for each batch. In the USA, the minimum standard required dose is 1,000 PFU [254] but this does not guarantee protection when challenged with MDV of high virulence [116,231]. The vaccine seed virus' protection potential varies and must be determined using protection tests (50% protective dose test and protection index test).…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of Factors That Influence Dose Variability of Marek's Disease Vaccines

et al. 2019

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for the wealth of knowledge, friendship, and for the patience and kindness shown to me since the very beginning. To my wonderful committee, Drs. Oscar Fletcher, James Guy, and Hsiao-Ching Liu, for helping me improve and shaping me into a better scientist. Many thanks to all of the students I have shared my time with at the laboratory, especially Dr. Allison Boone and Arithat Limsatanun, with whom it has been a pleasure to work. Thanks to Dr. Tobias Käser and Amanda Amaral for their help with the microscope camera. I would like to thank my friends for believing in me, especially Rocio, Esther, Giselle, Michelle, Jasmine, Jaylin and Javi. Every one of our conversations is threaded into this accomplishment, making it yours. Thanks also to my work family, first for their understanding, but most importantly for the comradery and countless laughs that served as motivation during these years. Most importantly, thanks to my family, for always being there and for showering me with unconditional love. v TABLE OF CONTENTS LIST OF TABLES .

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“…To reduce these costs, MD vaccines are often diluted, especially when the condemnation rates for 'leukosis' are very low (Schat and Baranowski, 2007;Schat and Nair, 2013). However, dilution of the vaccine reduces protection to virus replication and tumor development when birds are challenged with very virulent plus (vv þ )MDV strains (Gimeno et al, 2011) increasing the possibility of selection for more virulent strains (Atkins et al, 2013).…”

Section: Vaccinesmentioning

confidence: 99%

Vaccines and Vaccination Practices: Key to Sustainable Animal Production

Schat¹

2014

Encyclopedia of Agriculture and Food Systems

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Effect of Diluting Marek's Disease Vaccines on the Outcomes of Marek's Disease Virus Infection When Challenged with Highly Virulent Marek's Disease Viruses

Cited by 5 publications

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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

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

Evaluation of Factors That Influence Dose Variability of Marek's Disease Vaccines

Vaccines and Vaccination Practices: Key to Sustainable Animal Production

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