Genetic resistance to lymphoid tumor transplants

Area of Science:

• Poultry Science
• Immunology
• Virology

Background:

• Marek's disease (MD) is a significant concern in poultry.
• Understanding genetic resistance and age-related immunity is crucial for disease control.

Purpose of the Study:

• To evaluate the susceptibility of different chicken strains to Marek's disease tumor transplants.
• To investigate the influence of maternal antibodies and age at challenge on disease resistance.

Main Methods:

• Challenging day-old chicks of four different strains (Ottawa 4 & 5, Cornell K & S) with serial dilutions of Marek's disease tumor transplants (JMV-L, JMV-H) and transmissible lymphoid tumor (TLT).
• Assessing mortality and determining the lethal dose 50% (LD50) for each strain and tumor type.
• Investigating the effect of age at challenge on resistance to JMV-L in selected strains.
• Determining the chromosomal sex of tumor cells.

Main Results:

• Chicken strain significantly influenced resistance to JMV-L, with Strain S being the most susceptible (LD50 ~50 cells) and Strain 4 the most resistant (LD50 ~10,000 cells).
• Maternal antibodies against MD-related antigens did not significantly impact early resistance to JMV-L.
• JMV-H and TLT were highly lethal to all strains (LD50 <10 cells).
• Resistance to JMV-L increased rapidly with age; strains 4 and K were nearly resistant by 7 days, and Strain S showed increased resistance at 14 days compared to day-old chicks.

Conclusions:

• Significant genetic variation exists in chicken resistance to Marek's disease tumor transplants.
• Age at challenge is a critical factor in developing resistance to JMV-L.
• Tumor cell transplantability was confirmed using chromosomal sex markers.