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Characterization of Marek's disease virus-infected lymphocytes: discrimination between cytolytically and latently
Abstract:
Leukocyte suspensions derived from genetically Marek's disease (MD)-resistant N-line and MD-susceptible P-line chickens were fractionated at various times after exposure to the JM-10 clone of MD virus. At 3 and 5 days post exposure (DPE), during the productive-restrictive (cytolytic) phase, most infected spleen and thymus leukocytes were found to be low-density, nylon wool-adherent cells that possessed Fc receptors and surface Ia and IgM and were depleted by carbonyl iron treatment. This was true for leukocytes derived from N-line as well as those from P-line chickens. In contrast, most infected spleen cells derived from P-line chickens during the latent phase (i.e., after 7 DPE) were not found to have the above characteristics, with one exception: Ia antigen was demonstrated on the surface of latently infected cells. From these experiments it was concluded that the principal targets of the cytolytic JM-10 infection are B-cells, whereas the subsequent latent infection was found mostly in non-B-lymphocytes.
Insights
Marek's disease virus primarily infects B-cells during the cytolytic phase in chickens. Later, latent infections shift to non-B lymphocytes, regardless of genetic resistance.
Area of Science:
- Immunology
- Virology
- Avian Medicine
Background:
- Marek's disease (MD) is a significant lymphoproliferative disease in chickens caused by an oncogenic herpesvirus.
- Understanding the cellular targets of MD virus infection is crucial for developing effective control strategies.
- Genetic resistance and susceptibility to MD vary between chicken lines, influencing disease outcomes.
Purpose of the Study:
- To identify the specific leukocyte populations targeted by the JM-10 clone of Marek's disease virus.
- To differentiate between cellular targets during the acute cytolytic and latent phases of MD virus infection.
- To investigate if genetic resistance influences the cellular tropism of MD virus.
Main Methods:
- Fractionation of leukocyte suspensions from genetically resistant (N-line) and susceptible (P-line) chickens.
- Exposure of chickens to the JM-10 clone of MD virus and collection of samples at 3, 5, and 7+ days post-exposure (DPE).
- Characterization of infected leukocytes using density gradient centrifugation, nylon wool adherence, Fc receptor staining, Ia antigen detection, IgM expression, and carbonyl iron treatment.
Main Results:
- During the productive-restrictive (cytolytic) phase (3-5 DPE), infected leukocytes in both N-line and P-line chickens were predominantly low-density, nylon wool-adherent cells expressing Fc receptors, Ia, and IgM, and were depleted by carbonyl iron.
- In contrast, during the latent phase (after 7 DPE) in P-line chickens, infected spleen cells generally lacked these characteristics.
- An exception was the presence of Ia antigen on latently infected cells, suggesting a distinct cellular profile compared to the cytolytic phase.
Conclusions:
- The principal leukocyte targets of the cytolytic JM-10 MD virus infection are B-cells.
- Latent MD virus infections are primarily associated with non-B-lymphocytes.
- These cellular tropism differences are consistent across genetically resistant and susceptible chicken lines, highlighting B-cells as key targets in the initial viral replication cycle.