Characterization of “soluble” antigens derived from cells infected with Sendai and Newcastle disease viruses

Measles virus

“…These calculations also hold for the nucleocapsid of NDV (Waterson, 1964), and in this case the RNA content per average particle has been found, chemically, to be approximately 3.0 • 106 molecular weight units per particle. The complement-fixing "soluble" antigen extractable from cells infected with NDV is in fact identical with the nucleocapsid of the virion of NI)V (Rott, Waterson and Reda, 1963), and, although such a "soluble" complementfixing antigen from measles has not been prepared in a pure staff, it is probable that the complement-fixing antigen extracted by freezing and thawing cells (Black, 1959) is this substance, or a mixture of antigens including this NP antigen. In some pictures of the nucleoeapsid published by Almeida and Howatson (1963), there is a suggestion of a fine strand running in the otherwise apparently hollow central canal (Fig.…”

Immunochemical Study of Parainfluenza Virus (Type 2) in Amnion Cells

“…The possibility that they might represent viral ribonucleoprotein was suggested by the fact that their appearance coincided with the accumulation, in the cytoplasm of infected cells, of masses of virus-specific antigen demonstrable by specific immunofluorescence. This cytoplasmic antigen, which was present in maximal concentration during active production of virus, may correspond to the "soluble" antigen found with other myxoviruses, such as Newcastle disease virus, the ribonucleoprotem core of which can be shown to have immunological identity with "soluble" antigen extracted from cells infected with the corresponding virus (6). Attempts to demonstrate a similar relationship with the parainfluenza-amnion cell system have been hampered by difficulties in separating viral particles from cell fragments in the culture fluids.…”

Application of the single radial diffusion test for assay of antibody to influenza type A viruses

“…Standard methods were used to determine HI (3) 532 and NI (1) titers. CF tests were done by standard microtiter techniques (7) with nucleoprotein (NP) antigen (8).…”