MULTIPLICATION OF MYXOVIRUS PARAINFLUENZAE 1 (HVJ) AND ITS PERSISTENT INFECTION IN PS CELL

Abstract

Myxovirus parainfluenzae 1 (HVJ) multiplied readily and could be passaged serially in the cells of an established strain, PS cell. The viral growth in PS cells was recognized easily by marked cytopathic changes, production of hemagglutinin, and positive cyto-hemadsorption. The infectivity titers of HVJ in PS cell were almost the same as EID₅₀ titers, even when the egg-adapted virus was tested. It was concluded that PS cell was one of the most suitable host systems for HVJ.
The intracellular development of viral antigen in HVJ-infected PS cells was studied by the fluorescent antibody technique. Specific viral antigen was first found as fine granules in the perinuclear area. The antigen steadily increased in quantity and was observed as numerous granules distributed throughout the cytoplasm. Later, the fluorescent material began to form larger aggregates and, in some cases, such large masses occupied most of the cytoplasm. No fluorescent material was found in the nucleus at any stage of the infection. Eosinophilic intracytoplasmic inclusion bodies were found in the cells infected with HVJ. The nature of this inclusion body is now under investigation.
Viral carrier culture was obtained by prolonged cultivation of the cells which had survived HVJ-infection. The culture continued to produce virus over a period of many months. Immunofluorescent staining revealed that about 30% of cells in the culture appeared to contain viral antigen. Varying amount of viral antigen was contained in each of these cells. Thus, the cells which possessed very small amount of antigen as fine granules and the cells which contained large masses of fluorescent material were found simultaneously in the same culture. The nature of this viral carrier state was discussed in the light of the results obtained.