Small-plaque Virus Research Articles

Abortive infection of canine cells by herpes simplex virus: III. The interference of conditional lethal virus with an extended host range mutant

Two related phenomena take place in dog kidney (DK) cells doubly infected with MP dk −, a conditional lethal strain of herpes simplex virus, and MP dk + sp, a mutant capable of multiplying in DK cells. On one hand, the formation of infectious MP dk − virions is considerably increased (enhancement). On the other, the yield of infectious MP dk + sp is greatly reduced (interference). The relationship between enhancement and interference was studied by incubating DK cells at different temperatures after simultaneous and after staggered infection with the two mutants. The results show that conditions of infection which favor enhancement also favor minimal interference. Conversely, conditions favoring maximal interference do not favor enhancement. The results do not satisfy the hypothesis that MP dk − competes with MP dk + sp for cellular sites or for functional proteins specified only by MP dk + sp virus. The results are in accord with the predictions arising from the hypothesis that interference results from the formation of nonfunctional aggregates consisting of defective MP dk − subunits and potentially functional subunits specified by MP dk + sp.

Cell transformation in vitro and tumor induction in vivo by large- and small-plaque polyoma virus

Large-plaque and small-plaque polyoma virus suspensions transformed the same percentage of hamster kidney cells in vitro when similar exposure multiplicities were used. However, measurements on the adsorbed multiplicities showed that more small-plaque than large-plaque virus actually adsorbed to the cells and, therefore, that more transformed colonies per adsorbed hemagglutinin or plaque-forming unit were produced by large-plaque virus suspensions than by small-plaque. Large-plaque virus suspensions induced a high proportion of kidney tumors and few peritoneal tumors when inoculated intraperitoneally into newborn hamsters. With small-plaque virus suspensions, the incidence of tumors in the two anatomical sites was reversed. It is suggested that the difference in tumor sites is related to the difference in the adsorption characteristics of the two plaque types.

Some characteristics of large-plaque and small-plaque lines of polyoma virus

Suspensions of small-plaque and large-plaque lines of polyoma virus showed marked differences in the adsorption of virus particles to cells and to the hemagglutinin inhibitor released from cells. Small-plaque virus was more readily adsorbed than large-plaque virus, and this difference could be used as an adjunct to plaque size distribution in determining the predominant plaque type of virus suspensions. The suspensions of large- and small-plaque virus contained similar proportions of “full” particles of buoyant density 1.32 and “empty” particles of buoyant density 1.29.

Biologic Properties of Two Plaque Variants of Vesicular Stomatitis Virus (Indiana Serotype)

Summary Large plaque (LP) and small plaque (SP) variants were cloned from stock cultures of Indiana serotype, San Juan strain of vesicular stomatitis (VS) virus. Both variants bred true in cultures of chick embryo (CE) and L cells. Differences in infectivity, cytopathogenicity and growth potential were more pronounced when the two variants were compared in cultures of L cells. The LP and SP variants did not appear to differ significantly in the following properties: adsorption on CE or L cells, release from infected L cells, thermostability, growth in the presence of agar extracts, plaque size and growth under conditions of reduced bicarbonate concentrations, inactivation of infectivity by ultraviolet irradiation and cytotoxicity. Slight variations could be detected in neutralization by antibody and buoyant density in a cesium chloride density gradient. The LP variant was not conclusively inferior in its capacity to induce formation of interferon during the course of infection. However, definite evidence was obtained that the SP variant is more susceptible to the action of an exogenous interferon produced by infected L cells. Persistent infection of L cells could be established only with the SP variant. During an observation period of 5 months, carrier L cell cultures underwent periodic cycles of SP virus multiplication and cell destruction alternating with cycles of virus quiescence and slow repopulation of cultures by surviving L cells. No interferon could be detected in SP carrier cultures, but the L cells became more resistant to superinfection with the LP variant.

A comparison of some properties of polyoma virus and pneumonia virus of mice.

Polyoma virus (PY) and pneumonia virus of mice (PVM) are not related to each other serologically (1), but because of their similarity in size and their semi-ubiquitous presence in a latent form in mice, the possibility was considered that they belong to the same or related groups of viruses. Since sensitivity to ether serves to distinguish groups of viruses (2, 3), and since it is known that PY is ether resistant (4), the reaction of PVM towards ether was investigated. Ability of the 2 viruses to grow in tissue culture, and their in vivo effects on mouse lung were also compared.Materials and Methods. Three strains of PY were used in these experiments. Strain LID-1 (5) was kindly provided by Dr. R. J. Huebner. Strain Lp or large plaque virus was derived by Dr. R. Dulbecco by single plaque isolation from a stock originally provided by Dr. W.P. Rowe(6,7). Sp or small plaque virus was isolated from transformed hamster embryo cells after exposure to Lp virus(7). Both Lp and Sp viruses were kindly provided by D...

インフルエンザウイルスVon Magnus型不完全粒子の構造に関する研究

The morphological characteristics of “Standard Passage” virus and “Undiluted Passage” virus prepared for electron microscopy by the usual air-drying and by freeze-drying were compared with each other, and the densities of these viruses were also compared. The results were obtained as follows:1. SP virus isolated from allantoic fluids of infected eggs wee found to contain uniform particles of predominant by spherical shape with smooth surface, and as far as the appearence of particles was concerned, there was no great difference between an air-dried specimen and a frozen-dried specimen.2. In contrast, UP virus obtained from allantoic fluid of infected eggs vas found to be pleomorphic and there were great differences between an air-dried specimen and a frozen-dried specimen. That is to say, in the air-dried preparation, the majority of the particles appeared flattened and doughnuts like, but in the frozen-dried preparation, the majority of the particles appeared appromimately spherical in form and flatted or doughnut like particles disappeared.3. The density of the SF virus was estimated at 1.10 in blood albumin solution anti 1.23 in saline solution, meanwhile, the density of the UP virus was estimated at 1.07 in blood albumin solution and 1.16 in saline solution.From these results, the existence of basic structural differences between the two types of virus was estimated.