Although wild birds are natural hosts of avian influenza viruses (AIVs), these
viruses can be highly contagious to poultry and a zoonotic threat to humans. The
propensity of AIV for genetic variation through genetic shift and drift allows virus to
evade vaccine mediated humoral immunity. An alternative approach to current vaccine
development is induction of CD8+ T cells which responds to more conserved epitopes
than humoral immunity and targets a broader spectrum of viruses. Since the memory
CD8+ T lymphocyte responses in chickens to individual AIV proteins have not been
defined, the modulation of responses of the memory CD8+ T lymphocytes to H5N9 AIV
hemagglutinin (HA) and nucleocapsid (NP) proteins over a time course were evaluated.
CD8+ T lymphocyte responses induced by intramuscular inoculation of chickens with
AIV HA and NP expressing cDNA plasmids or a non-replicating human adenovirus
vector were identified through ex vivo stimulation with virus infected, major
histocompatibility complex (MHC) matched antigen presenting cells (APCs). The IFN?
production by activated lymphocytes was evaluated by macrophage production of nitric
oxide and ELISA. MHC-I restricted memory T lymphocyte responses were determined at 10 days and 3, 5, 7 and 9 weeks post-inoculation (p.i). The use of non-professional
APCs and APC driven proliferation of cells with CD8+ phenotype correlated with the
activation of CD8+ T lymphocytes. The responses specific to nucleocapsid protein (NP)
were consistently greater than those to the hemagglutinin (HA) at 5 weeks when the
CD8+ T cell responses were maximum. By 8 to 9 weeks p.i., responses to either protein
were undetectable. The T lymphocytes also responded to stimulation with a heterologous
H7N2 AIV infected APCs. Administration of booster dose induced secondary effector
cell mediated immune responses which had greater magnitudes than primary effector
responses at 10 days p.i. Flow cytometric analysis (FACS) of the T lymphocytes
demonstrated that memory CD8+ T lymphocytes of chickens can be distinguished from
naive lymphocytes by their higher expression of CD44 and CD45 surface antigens.
CD45 expression of memory lymphocytes further increases upon ex vivo stimulation
with APCs expressing AIV. This is the first characterization of avian memory responses
following both primary and secondary expression of any individual viral protein.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2009-12-7534 |
| Date | 2009 December 1900 |
| Creators | Singh, Shailbala |
| Contributors | Collisson, Ellen W., Lupiani, Blanca |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | application/pdf |
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