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ARS Home » Southeast Area » Athens, Georgia » U.S. National Poultry Research Center » Exotic & Emerging Avian Viral Diseases Research » Research » Publications at this Location » Publication #387404

Research Project: Intervention Strategies to Predict, Prevent and Control Disease Outbreaks Caused by Emerging Strains of Virulent Newcastle Disease Viruses

Location: Exotic & Emerging Avian Viral Diseases Research

Title: In situ gene expression in early stage of virulent Newcastle disease in chickens

Author
item BROWN, CORRIE - University Of Georgia
item ZHANG, JIAN - University Of Georgia
item Pantin-Jackwood, Mary
item KIMITROV, KIRIL - Texas A&M Veterinary Medical Diagnostic Laboratory
item FERREIRA, HELENA - Orise Fellow
item Suarez, David

Submitted to: Veterinary Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/16/2021
Publication Date: N/A
Citation: N/A

Interpretive Summary: Newcastle disease, caused by Newcastle disease virus (NDV), represents a serious threat to the poultry industry. Infection with virulent NDV strains in chickens results in severe disease and high mortality. Previous studies indicate that an over-vigorous innate immune response in the birds may be occurring with infection with NDV. The innate immune response consists of many factors dominated by pro-inflammatory cytokines that serve to decrease infection in the early stages and initiate the development of the specific immune response. When this innate immune response is hyper-responsive, it can create severe disease in the host and has been referred to as a “cytokine storm”. In this study, selected lymphoid and reproductive tissues from three-week-old chickens and 62-week-old hens which were inoculated with a virulent NDV were examined. Immunohistochemistry for NDV, T, and B cells, as well as RNAScope assays for four cytokines revealed extensive production of interleukin 1ß and interleukin 6 in lymphoid tissues, often coinciding with similar levels of NDV antigen. In the three-week-old birds, T cell populations initially expanded but by day 3 numbers were below control levels. B cells underwent a similar expansion, but in some tissues, notably spleen, cecal tonsils, and bursa of Fabricius, remained elevated. Cytokine responses in the 62-week-old hens were overall lower than what was seen in the three-week-old birds. Also, in these older birds, there was more prolonged production of both T and B cells. This study helps in understanding the involvement of the bird immune system in the pathogenesis caused by virulent NDV.

Technical Abstract: Selected lymphoid and reproductive tissues from groups of three-week-old chickens and 62-week-old hens which were inoculated orally and conjunctivally with 106 EID50 of a Newcastle disease virus (NDV) from the California 2018-2019 outbreak, and euthanized at one, two, and three days post-infection were examined. Immunohistochemistry for NDV, T, and B cell lymphocytes as well as RNAScope assays for four cytokines (IL1ß, IL6, IFN', and TNFa) revealed extensive production of IL1ß and IL6 in lymphoid tissues, often coinciding with similar levels of NDV antigen. IFN' was only found infrequently in the same lymphoid tissues and TNFa was rarely found. In the three-week-old birds, T cell populations initially expanded but by day 3 numbers were below control levels. B cells underwent a similar expansion, but in some tissues, notably spleen, cecal tonsils, and bursa of Fabricius, remained elevated. Cytokine responses in the 62-week-old hens were overall lower than what was seen in the three-week-old birds. Also, in these older birds, there was more prolonged production of both T and B cells.