Abstract
The duration and specificity of the in vitro changes in chicken red blood cells following treatment with 2 influenza viruses (PR8 strain of influenza A and the Lee strain of influenza B) and Newcastle disease virus (NDV) have been investigated. The treated cells show loss of agglutinability and absorptive capacity for fresh homologous and heterologous virus, and these modifications may persist for as long as 21 days. The most marked changes are produced by PR8, slightly less marked ones by Lee, and least following treatment with NDV. The alterations produced in red blood cells are to a degree specific for the virus used. Expts. were carried out in an attempt to correlate alterations in infected chick embryos with those in treated red blood cells. It was found, however, that chick embryos infected by NDV were no longer susceptible to infection by PR8. The hemagglutination phenomenon is, therefore, an inadequate model for the study of viral infections.