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Chronological observations of feather pulp lesions in chickens inoculated with Marek's disease virus
Abstract:
Observations of the feather pulp from chickens inoculated with Marek's disease (MD) virus revealed diverse lesions similar to those in the peripheral nerves of chickens infected with MD. These lesions were categorized as follows: R1-type lesions = from minimal perivascular to diffuse infiltration of small lymphocytes mixed with a few medium lymphocytes or blast cells; R2-type lesion = edema and cellular infiltration consisting of plasma cells and small lymphocytes; and T-type lesion = tumorous proliferation of lymphoid cells predominantly composed of medium lymphocytes or blast cells. Chronological observations of the feather pulp biopsies taken at 2-week intervals from individual chickens revealed the lesion progression R1-type leads to T-type, or R1-type leads to R2-type. The former progression was usually seen in birds showing evidence of both persistent nuclear-inclusion (NI) formation in the feather-follicle epithelium (FFE) and development of lymphoid tumors in the viscera. The latter progression was seen exclusively in chickens that showed transient NI formation in the FFE, regardless of the incidence of MD.
Insights
Marek
Area of Science:
- Avian Pathology
- Immunology
- Virology
Background:
- Marek's disease (MD) is a significant lymphoproliferative disease in chickens caused by MD virus.
- Feather pulp offers a unique site for observing MD virus-induced pathological changes.
- Understanding lesion progression is crucial for diagnosing and managing MD.
Purpose of the Study:
- To characterize and categorize lesions in chicken feather pulp following MD virus inoculation.
- To chronologically observe the progression of these lesions.
- To correlate lesion progression with viral indicators like nuclear inclusions and tumor development.
Main Methods:
- Inoculation of chickens with Marek's disease virus.
- Biopsy of feather pulp at 2-week intervals for chronological observation.
- Categorization of observed lesions into R1-type, R2-type, and T-type based on cellular composition and morphology.
- Assessment of nuclear-inclusion (NI) formation in feather-follicle epithelium (FFE) and development of visceral lymphoid tumors.
Main Results:
- Three distinct lesion types (R1, R2, T) were identified in feather pulp, mirroring peripheral nerve pathology.
- Lesion progression followed two main pathways: R1-type to T-type or R1-type to R2-type.
- R1-to-T progression correlated with persistent NI formation and visceral tumors.
- R1-to-R2 progression occurred in chickens with transient NI formation, irrespective of MD incidence.
Conclusions:
- Feather pulp lesions provide a valuable model for studying Marek's disease pathogenesis.
- Lesion progression pathways in feather pulp are linked to specific viral activity patterns (NI formation) and disease outcomes (tumorigenesis).
- The study highlights the utility of feather pulp analysis for understanding MD virus infection dynamics.
