- Volume 14, Issue 3, 1972

The number and size of plaques formed by the saukett strain of poliovirus type 3 were enhanced in Yaba virus (YV)-infected cells. Similar enhancement occurred when Shope fibroma virus or a mutant strain of vaccinia virus was used instead of Yaba virus. Enhancement required at least 3 hr pre-infection and was greatest when cultures were pre-infected for 72 hr. An inoculum as small as 0.004 TCD50/cell was effective in enhancing poliovirus plaque number. Some characteristics of the enhancement by Yaba virus of plaque formation by Sindbis virus are also presented.

The mechanism of the enhancement by Yaba virus (YV) of poliovirus plaque formation was studied. Poliovirus adsorbed equally well to both YV-infected and normal JINET cells. Infectious RNA of poliovirus was also enhanced in YV-infected cells, thus indicating the step or sequence of steps of poliovirus growth cycle enhanced by YV may be those subsequent to poliovirus uncoating. One-step growth experiments revealed that the final yield and the release of progeny poliovirus were enhanced in YV-infected cells. This may account for the enhancement of the plaque size of poliovirus. The enhancement of the plaque number of the super-infecting virus by YV appeared to result from the interaction between a single YV-infected cell and a single infecting polio virus genome which failed to express its function under ordinary conditions. This enhancement may be brought about by the disturbance by YV of a host cellular defence mechanism other than that mediated by interferon.

The proteins from bacteriophage Ø29 have been dissociated with 1% SDS and 2% 2-mercaptoethanol and have been examined by SDS-acrylamide gel electrophoresis. Seven different polypeptides bands have been detected in the purified virus. One of the bands (b 1) is frequently detected in different positions suggesting that it represents an aggregate rather than a very large polypeptide. The molecular weights of the other polypeptide bands (b2, b3, b3–4, b4, b5 and b6) estimated by co-electrophoresis with marker proteins are 93,000; 75,000; 65,000; 53,000; 41,000 and 30,000. Protein bands b2, b4 and b6 compose 80% of the bacteriophage. The six structural polypeptides described here could account for approximately 60% of the information contained in the virus DNA.

Glucosamine inhibited the formation of infectious fowl plague, Sindbis, and Semliki Forest virus but had little or no effect on the multiplication of vesicular stomatitis, Newcastle disease, and polio virus. 2-deoxy-d-glucose had a somewhat stronger effect than glucosamine. Only the production of virus glycoproteins seemed to be affected. Almost normal amounts of virus RNA and RNA polymerase were synthesized, and RNP-antigen activities reached control levels. After infection with fowl plague virus the nuclei and cytoplasm of cells incubated with glucosamine showed brilliant staining with fluorescent antibodies against RNP-antigen, whereas haemagglutinin-specific fluorescence was visible weakly in the cytoplasm. The virus-induced alterations of the cell surface, as measured by the agglutinability with Concanavalin A, were abolished by glucosamine.

The paracrystalline structures appearing in human adenovirus-infected KB and human embryonic lung fibroblast cells have been shown by immunofluorescent-staining procedures to be serologicaly related to the adenovirus core protein(s) — the arginon and P-antigen components described by others. Cytochemical staining and arginine-depletion studies demonstrated the arginine-rich nature of the paracrystalline formations. It was possible, using proflavine or decreased amounts of arginine in the culture medium, to block the assembly of intact virus particles without affecting the appearance of the paracrystals.