Studies on the soluble antigen of influenza virus: III. The decreased incorporation of S antigen into elementary bodies of increasing incompleteness

Abstract

A comparison was made of the extent of incorporation of S antigen into fully infectious and partially incomplete elementary bodies (EB) as derived from allantoic fluids following inoculation of diluted standard virus on the one hand, and of undiluted native or heated (37°) standard, or undiluted passage seeds, on the other. Whereas on the average, 40 HA units (chicken red cells) of fully infectious EB ( ID 50 HA > 10 6 ) were required to yield one unit of S antigen after exposure to ether, increasingly more HA units were needed as the ID 50 HA ratios of the progenies decreased; i.e., for each successive tenfold reduction in the ID 50 HA ratio the number of HA units required increased in twofold steps. EB preparations derived from infected allantoic membranes yielded regularly less S antigen than those obtained from the allantoic fluids of the corresponding chick embryos in accordance with the fact that the tissue-bound virus materials always reveal ID 50 HA ratios 8–15 log 10 units lower than the progenies liberated from the cells. Furthermore, ether was found to be more detrimental to the hemagglutinating and antigen activities of EB suspensions derived from tissues than of those found in the allantoic fluids, suggesting that the former are as yet structurally deficient. The decreasing incorporation of S antigen into incomplete virus particles cannot be ascribed to a lack in its production in the tissues, since similar quantities were found free in the infected membranes as long as the total yield of hemagglutinins was not reduced. Exposure of incomplete virus derived from infected HeLa cell cultures to ether gave results similar to those observed with EB suspensions obtained from allantoic membranes. The implications of these findings have been discussed.