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In vitro infection studies with infectious laryngotracheitis virus
Abstract:
Infectious laryngotracheitis (ILT) virus strains were studied for their ability to infect chicken macrophages, lymphocytes, and kidney cells in vitro. Although macrophages were as susceptible as chicken kidney cells to infection, replication of most virus strains in macrophages was markedly restricted. Only a few isolates induced progressive infections in macrophages, and even with these the donor of the macrophages influenced replication. Thus, it appears that both cell genotype and virus genotype may help determine the extent of restriction of virus replication. Macrophages were more susceptible to an attenuated vaccine strain of ILT virus than to virulent virus strains. Spleen lymphocytes, peripheral blood lymphocytes, thymocytes, bursal lymphocytes, buffy coat leukocytes, and activated T-cells were nearly or totally refractory to infection by ILT virus.
Insights
Infectious laryngotracheitis (ILT) virus infects chicken kidney cells and macrophages, but replication is restricted in macrophages. Both chicken and virus genetics influence ILT virus replication, with attenuated strains showing higher susceptibility.
Area of Science:
- Avian Virology
- Immunology
- Cell Biology
Background:
- Infectious laryngotracheitis (ILT) is a significant respiratory disease in poultry.
- Understanding virus-host cell interactions is crucial for controlling ILT.
- Previous studies have focused on epithelial cells, with limited data on immune cells.
Purpose of the Study:
- To investigate the susceptibility and permissiveness of chicken immune cells and kidney cells to Infectious laryngotracheitis (ILT) virus in vitro.
- To determine the factors influencing ILT virus replication in macrophages.
- To compare the infectivity of virulent and attenuated ILT virus strains in different chicken cell types.
Main Methods:
- In vitro infection assays using primary chicken macrophages, lymphocytes (spleen, peripheral blood, thymocytes, bursal), and kidney cells.
- Inoculation with various virulent and attenuated Infectious laryngotracheitis (ILT) virus strains.
- Assessment of viral replication and cytopathic effects.
Main Results:
- Chicken macrophages and kidney cells showed susceptibility to ILT virus infection.
- Replication of most ILT virus strains was significantly restricted in macrophages.
- Macrophage donor genetics and virus genotype influenced replication extent.
- Attenuated ILT virus vaccine strains replicated more efficiently in macrophages than virulent strains.
- Lymphoid cells (lymphocytes, thymocytes, bursal lymphocytes, leukocytes, T-cells) were largely refractory to ILT virus infection.
Conclusions:
- Chicken macrophages are susceptible but generally restrict ILT virus replication, indicating a role for cell and virus genotype in determining infection outcome.
- ILT virus exhibits differential tropism, with immune cells like lymphocytes being largely resistant.
- These findings provide insights into the cellular basis of ILT pathogenesis and host-virus interactions.