2.2.2: Characterization of the Mucosal Immunity in Chickens Administered a Live Attenuated Infectious Laryngotracheitis Virus (ILTV) Chicken Embryo Origin (CEO) Vaccine Alone or Combined with Select Viral Respiratory Vaccines
Maricarmen García and Robert M. Gogal Jr.
ILTV produces a localized infection in bird respiratory tissues. The trachea epithelium is one of the main sites where the virus replicates productively and establishes latency. Control of infectious laryngotracheitis (ILT) in poultry has been achieved primarily via vaccination with live attenuated vaccines. Although characterized by their ability to regain virulence, the chicken embryo origin (CEO) vaccines are still effective in containing outbreaks of the disease and significantly decreasing virus shedding. To date, no new generation of vector vaccines or potential gene deleted vaccines have been able to achieve the same level of protection as the CEO vaccines. Surprisingly, data are still lacking regarding the protective immune responses elicited by these vaccines. CEO vaccines induce a mucosal immunity when administered via eye drop, spray or in the drinking water. The nasal cavity, conjunctiva as well as the para-ocular harderian gland are the first tissues to encounter the virus. The nasal-associated lymphoid tissue (NALT), Harderian gland (HG), and conjunctiva-associated lymphoid tissue (CALT) are believed to play a key role in the induction of respiratory immunity. A comprehensive understanding of the mucosal immune responses elicited by respiratory live attenuated vaccines in poultry is critical in order to appropriately develop new vaccines and adjuvants. The overall objective of this project is to identify the key innate and adaptive immune pathways associated with the administration of the ILTV CEO vaccine pre and post challenge with an ILTV wild-type strain. We will also ascertain whether these mucosal immune pathways are altered when the CEO vaccine is co-administered with either infectious bronchitis virus (IBV) or Newcastle disease virus (NDV) vaccines. We will first optimize the isolation and enrichment of lymphocytes from the NALT, CALT, HG, and trachea of specific pathogen free (SPF) chickens. Enriched peripheral blood lymphocytes will serve as a control. We plan to then phenotype the cells and measure cytokine levels systemically and post-stimulation of specific lymphocytes populations, in vitro. Each year duplicate sets of experiments will be performed to complement the budgetary constraints.
Yearly Goals:
Year 1: Immune response post-CEO vaccination
SPF chickens will be vaccinated once or twice with ILTV CEO vaccine. Two weeks post vaccination lymphocytes isolated from mucosal tissues and blood will be phenotyped and cytokine analysis will be performed ± histopathology.
Year 2: Immune response post-challenge in ILTV vaccinated chickens
CEO vaccinated SPF chickens will be challenge two to three weeks post vaccination. Two weeks post-challenge lymphocytes isolated from mucosal tissues and blood will be phenotyped and cytokine analysis will be performed ± histopathology.
Year 3: Immune response post co-administration of viral respiratory vaccines
SPF chickens will be vaccinated with CEO/IBV and CEO/NDV once at two weeks-of-age. Two weeks post vaccination lymphocytes isolated from mucosal tissues and blood will be phenotyped and cytokine analysis will be performed ± histopathology.
Year 4: Immune response post-challenge of ILTV and IBV vaccinated chickens
Dually and single vaccinated groups of SPF chickens will be challenge with either ILTV or IBV. Two weeks post-challenge lymphocytes isolated from mucosal tissues and blood will be phenotyped and cytokine analysis will be performed.
Year 5: Immune response post-challenge of ILTV and NDV vaccinated chickens
Dually and single vaccinated groups of SPF chickens will be challenge with either ILTV or NDV. Two weeks post-challenge lymphocytes isolated from mucosal tissues and blood will be phenotyped and cytokine analysis will be performed.
Outcomes:
Upon completion of this project, we will have developed a reliable immune testing panel for the assessment of mucosal and systemic immune responses elicited by live attenuated respiratory vaccines of poultry. In particular, we anticipate that this project will shed new light on the specific immune responses induced by the ILTV CEO vaccine. We also predict that the results from this study will help guide the design of future ILTV vaccines and adjuvants.
