In sum, for both viruses at both temperatures, detection of maximal numbers of antigen-positive cells correlated with high titers (compare Figure 1A and 2A) and increasing CPE ( Figure 1B ). By 72 and 120 hrs pi considerable loss of cells from the culture was evident and this correlated with the drop off in viral titers at these time points ( Figure 1A ). Thus, we conclude that in the context of maximal infection in which there were no additional target cells available for infection within the finite surface area of the HAE culture, ongoing replication in antigen-positive cells shown at 48 and 72 hrs pi resulted in increased cell death. This CPE led to a reduction in the number of viable, virus-producing cells and in turn, to a reduction in progeny virus. Although A/Dk/Eng/62 induced CPE when sufficient titers were generated at 37uC, one consequence of restricted replication of this avian influenza virus at 32uC was a reduction in overt CPE in HAE, even at later time points associated with considerable viral titers.