The influenza A/chicken/Pennsylvania/1/83 (H5N2) virus is the first known example of an influenza virus isolated from a natural infection which contained primarily defective interfering particles (T. M. Chambers and R. G. Webster, J. Virol. 61, 1517-1523, 1987). In chickens, coinoculation of this virus together with the closely related but highly virulent influenza A/chicken/Pennsylvania/1370/83 virus results in reduced mortality compared to virulent virus infection alone(Bean et al., J. Virol. 54, 151-160, 1985). The biological basis of this protective effect has not been established. Protective activity required ≥100-fold excess input of protecting virus over virulent virus, functioned effectively during the first generations of virulent virus multiplication, and also functioned against an antigenically heterologous (H7N7) virulent influenza virus. Protection was correlated with the complete inhibition of virulent virus spread to the brain of infected chickens. Plaque-purified chicken/Pennsylvania/1/83 virus depleted of defective interfering particles, and β-propiolactone-inactivated virus, had no protective effect. These characteristics are consistent with the hypothesis that protection was the result of defective interfering particle-mediated interference with virulent virus multiplication within the respiratory tract of the chicken.
|Number of pages||6|
|State||Published - Jul 1991|
Bibliographical noteFunding Information:
This work was supported by U.S. Public Health Service Grant No. Al 29680 from the National Institute of Allergy and Infectious Diseases, by Cancer Center Support (CORE) Grant CA-21 765, and by American Lebanese Syrian Associated Charities. We thank Gary R. Burleson (U.S. Environmental Protection Agency) for help and advice regarding nonspecific immunity, and John Freeman and Tim Thomas for technical assistance.
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