What is the clinical evidence from this study?

Population: Marek's disease virus-induced immunosuppression. Intervention: Early infection with very virulent plus MDV (vv+MDV) strain 648A vs. Chickens not vaccinated with CEO ILTV vaccine. Primary outcome: Clinical scores, gross lesions, histopathologic lesion scores, and load of ILTV transcripts in trachea after ILTV challenge (p=< 0.05).

What question did this study set out to answer?

To evaluate the impact of late Marek's disease virus-induced immunosuppression on infectious laryngotracheitis vaccination efficacy in commercial meat-type chickens and establish a standardized laboratory model.

May 23, 2016Avian PathologyOpen Access

Early infection with Marek’s disease virus can jeopardize protection conferred by laryngotracheitis vaccines: a method to study MDV-induced immunosuppression

Q: What are the key findings of this study?

Early infection with very virulent plus Marek's disease virus completely abrogated the protection conferred by the CEO infectious laryngotracheitis vaccine against ILTV challenge.

Q: What question did this study set out to answer?

To evaluate the impact of late Marek's disease virus-induced immunosuppression on infectious laryngotracheitis vaccination efficacy in commercial meat-type chickens and establish a standardized laboratory model.

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Key result

Early infection with very virulent plus Marek's disease virus completely abrogated the protection conferred by the CEO infectious laryngotracheitis vaccine against ILTV challenge.

Why the study?

Does early infection with vv+MDV abrogate the protection conferred by CEO ILT vaccine against ILTV challenge in commercial poultry?

Key Points

To evaluate the impact of late Marek's disease virus-induced immunosuppression on infectious laryngotracheitis vaccination efficacy in commercial meat-type chickens and establish a standardized laboratory model.
Meat-type chickens with maternal antibodies were infected at one day of age with very virulent plus Marek's disease virus (vv+MDV strain 648A) and administered MD vaccines (HVT, HVT+SB-1, or CVI988).
Chickens received chicken-embryo-origin (CEO) infectious laryngotracheitis (ILT) vaccine via water at 14 days and were challenged intratracheally with ILT virus at 30 days.
Outcomes were monitored through daily clinical evaluations, gross and histological tracheal lesion scoring, and tracheal ILT viral transcript quantification.
Infection with vv+MDV strain 648A completely abrogated protection conferred by the CEO vaccine against ILTV challenge, even in chickens vaccinated at day one with HVT, HVT+SB-1, or CVI988.
Birds exposed to vv+MDV before CEO vaccination developed clinical scores, gross lesions, histopathology scores, and tracheal ILTV transcript loads equivalent to unvaccinated controls (P < 0.05).

Structured PICO

Does early infection with vv+MDV abrogate the protection conferred by CEO ILT vaccine against ILTV challenge in commercial poultry?

Population

Commercial meat-type chickens bearing maternal antibodies against MDV, evaluated for the effect of early infection with vv+MDV on the efficacy of CEO ILT vaccine.

Intervention

Early infection (day of age) with very virulent plus MDV (vv+MDV) strain 648A, followed by chicken-embryo-origin (CEO) infectious laryngotracheitis (ILT) virus vaccine at 14 days of age and ILTV challenge at 30 days of age

Comparator

Chickens not vaccinated with CEO ILTV vaccine

Outcome

Development of ILT (clinical signs, gross and histological lesions in trachea, and quantification of ILTV transcripts in trachea)surrogate

Main Result

p-value: p=< 0.05

Early infection with very virulent Marek's disease virus completely abrogates the protective efficacy of infectious laryngotracheitis vaccines in chickens.

Discussion

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Implication

May compromise ILT vaccine efficacy in vv+MDV-exposed flocks; leaves open generalizability to field conditions and other vaccines.

Cite This Study

Faiz et al. (2016) studied Marek's disease virus-induced immunosuppression. Early infection with very virulent plus MDV (vv+MDV) strain 648A vs. Chickens not vaccinated with CEO ILTV vaccine was evaluated on Clinical scores, gross lesions, histopathologic lesion scores, and load of ILTV transcripts in trachea after ILTV challenge (p=< 0.05). Early infection with very virulent plus Marek's disease virus completely abrogated the protection conferred by the CEO infectious laryngotracheitis vaccine against ILTV challenge.

synapsesocial.com/papers/6a9b272c94ef5ed6bfd3a594 https://doi.org/10.1080/03079457.2016.1191618

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Early infection with Marek’s disease virus can jeopardize protection conferred by laryngotracheitis vaccines: a method to study MDV-induced immunosuppression

Key Points

Structured PICO

Main Result

Discussion

Implication

Cite This Study

Early infection with Marek’s disease virus can jeopardize protection conferred by laryngotracheitis vaccines: a method to study MDV-induced immunosuppression

Key Points

Structured PICO

Main Result

Discussion

Implication

Cite This Study

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