Levels Of Free Sialic Acid Research Articles

Summary The endodermal cells of chorioallantoic membranes, from eggs infected with the PR8 strain of influenza virus, fixed and stained with alcian blue PAS stain 24 hr postinoculation, showed a diminution in the histochemical reaction for acid mucins; a negative reaction 48 and 72 hr postinoculation; stainable material reappeared at the 96th hr and increased up to 144 hr. Strongly positive reactions for the periods above were observed in the cells of membranes from noninfected eggs. Sections of membranes from infected and noninfected eggs stained with fluorescent PAS stain, acridine orange stain, and Bismarck brown stain showed histochemical changes similar to the above. The staining reactions of cells of membranes from eggs inoculated with virus inactivated by ultraviolet irradiation were similar to those from noninfected eggs. The reactions of membranes from eggs producing incomplete virus paralleled those of membranes from eggs inoculated with complete, active virus. The staining reactions of the positive material of the endoderm was not altered by incubating sections of membranes from noninfected eggs with diastase or testicular hyaluronidase; sections incubated with Vibrio cholerae neuraminidase resembled those from infected eggs 48 hr postinoculation. These data suggested a possible alteration in the amounts of total, bound and free sialic acids in the allantoic fluids of eggs infected with influenza virus. The total sialic acid content of allantoic fluids from noninfected and infected eggs increased with time, the variations observed were not significant; bound sialic acid in fluids from noninfected eggs increased with time, the levels in fluids from infected eggs remained unchanged; the levels of free sialic acid in fluids from infected eggs were significantly higher than those in noninfected eggs. The relationships between neuraminidase of viral origin, mucopolysaccharide, mucoprotein and inhibitor substance of allantoic fluid are discussed.